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Thesis/Dissertation Announcements

Thesis/Dissertation Announcements

Dissertation Defense

Probiotic regulation of fat-storage via Angiopoietin-like 4 (ANGPTL4)


Name: Priscilla Pham


Major Advisor: Dr. Bob McLean           

Committee Members: Dr. Dana García, Dr. Shannon Weigum, Dr. Dhiraj Vattem, Dr. Jennifer Spinler

and Dr. Vatsala Maitin

 

September 20, 2019, 3:30pm, Ingram 3203


 

Gut microbiota have been implicated in obesity by influencing nutrient digestion/absorption and host metabolic pathways related to fat synthesis and storage. One key target is Angiopoietin-like 4 (ANGPTL4), a protein that is regulated by the gut microbiota and responsible for inhibiting lipoprotein lipase (LPL). LPL hydrolyzes triglycerides to free fatty acids for subsequent storage in adipose tissue. Therefore, identifying microbial factors able to enhance ANGPTL4 may reduce fat storage. Probiotics are widely used for the beneficial shift of microbial composition; thus, probiotic bacteria and probiotic-derived bioactive compounds with stimulatory activity towards ANGPTL4 may thus serve a protective function against diet-induced obesity. The objective of this study was to explore the anti-obesity potential of certain bioactives produced by Bifidobacterium longum by influencing ANGPTL4, a key molecular target that regulates fat-storage and lipid metabolism; and elucidating the mechanism of action using in vitro and in vivo model systems. Enterocytic cell line HT-29 were used to examine whether the use of freeze-dried B. longum (FBLS) retained bioactivity towards ANGPTL4 and the mechanism of ANGPTL4-regulation. Next, the effects of FBLS on fat storage were investigated in 3T3-L1 adipocytes. Caenorhabditis elegans were used as an in vivo model to evaluate the dietary effects of FBLS on lipid metabolism genes. Results indicate that the modulatory activity of FBLS towards enterocytic ANGPTL4 may be partially dependent on its transcription factor PPARa. In adipocytes, FBLS upregulated ANGPTL4 and increased LPL activity. However, FBLS stimulation of ANGPTL4 may potentially reduce further fat storage accumulation by degrading intracellular LPL. In C. elegans, FBLS as a supplement to the normal C. elegans diet is capable of regulating lipid metabolism genes. This study provides insight for species-specific microbial regulation of obesity via ANGPTL4-mediated mechanism. Further examination of the exact mechanism and direct connections between FBLS and the possible anti-obesity effects of ANGPTL4 in the intestine and adipose tissue are needed.


Bio:  Priscilla Pham is from Houston, Texas and received her BS in Human Nutrition and Foods from Prairie View A&M University. In 2010, she entered the Master’s in Human Nutrition Program at Texas State University and began her research in the Molecular and Cellular Nutrition Laboratory under Dr. Vatsala Maitin. As a PhD Biology student, she continued her research work under the advisement of Dr. Bob McLean and Dr. Dhiraj Vattem.


Thesis Defense

A STATISTICALLY DESIGNED KARST FEATURE SURVEY, AND FACTORS CONTROLLING KARST FEATURE DENSITY AND DISTRIBUTION


Lorena Roque Martinez

Major Advisor: Dr. Benjamin Schwartz - Department of Biology, Texas State University; Edwards Aquifer Research and Data Center

Committee Members: Dr. Jennifer Jensen - Department of Geography, Texas State University, & Dr. Todd Swannack - US Army Engineer Research and Development Center

Monday, July 22, 2019, 10:00 AM, Freeman Aquatic Biology 130


 

 Karst feature inventories provide data that are used to evaluate a site’s degree of hydrogeologic connectivity to local and regional flow systems, as well as its environmental and ecological sensitivity. For developments proposed on the Edwards Aquifer recharge zone, TCEQ rules require a geological assessment and full-coverage karst feature inventory on the property. However, visual surveys may be subjective, depending on the experience of the person performing a survey, and are extremely time intensive. Considering this, my research question was: is it possible to develop an independent method for identifying the most sensitive recharge areas for visual surveys, and to provide a means for assessing the accuracy of surveys?

A partial, statistically-designed, karst feature survey of the 17 km2 Freeman Center of Texas State University in San Marcos, Texas resulted in 60 documented karst features, including 3 sinkholes ground-truthed after detection using GIS methods. The survey design used for Freeman was then tested on Camp Bullis, near San Antonio, TX (a site with a complete karst feature inventory), which revealed that random surveying does not yield representative karst feature density results, because karst features are clustered. The entirety of Camp Bullis was then analyzed for factors that influence karst feature density and distribution.

An Ordinary Least Squares model determined that slope, distance to nearest flowline, lithology, and apparent resistivity were significant predictors of karst feature density (AICc=7169.4; R= 0.13; p<0.01). A Geographically Weighted Regression was used to visualize the nonstationarity of predictor variables (AICc=5636; R=0.79). Both models reveal spatial autocorrelation of residuals, indicating model misspecification. Despite concluding that karst features density is difficult to model, these methods offer a more nuanced understanding of factors controlling karst feature distribution, and the significance of physical factors on Camp Bullis.


Bio:  Lorena grew up in San Benito, Texas, a growing city in the Rio Grande Valley. She earned her B.S. in Environmental Science with a focus in Geology from The University of Texas at Austin. Her interest in karst hydrogeology, field research, and caving was cemented after working at the Buffalo National River in Arkansas. She entered the Aquatic Systems Masters program at Texas State University in Fall 2017. Lorena is currently looking for opportunities where her GIS knowledge together with hydrogeologic field techniques can be used for the protection of water resources in the state of Texas.


Thesis Defense
Vegetation Survey of the Yegua Knobbs Preserve, Bastrop and Lee Counties, Texas 

 


Diana K. Digges
Major Advisor: Dr. David E. Lemke, Department of Biology, Texas State University  

Committee Members: Dr. Paula Williamson, Department of Biology, Texas State University  

                                    Dr. Sunethra Dharmasiri, Department of Biology, Texas State University                                                 

Tuesday, July 02, 3:00 pm, Supple Science Building, Norris Room  


 The Yegua Knobbs Preserve (YKP) is a private, nearly rectangular 122-hectare tract that sits on the Bastrop and Lee County lines in the Oak Woods and Prairies natural region of east-central Texas. This region is considered an ecotone, where the communities from the bordering natural regions, the Pineywoods to the east and the Blackland Prairies to the west, merge. A species inventory was done to identify the vascular plants present at the preserve for a growing season. Woody vegetation was sampled using the line intercept method, and herbaceous components were sampled using the quadrat method. Analysis of the qualitative and quantitative data led to the designation of six plant communities at YKP, four dominated by woody vegetation and two herbaceous. The lack of exotic species present on the preserve was also noted. These communities referred to others previously discussed for the Oak Woods and Prairies, Pineywoods and Blackland Prairies natural regions.


 Bio:  Diana grew up in Kerrville, Texas. She received her B.A. in Biology from University of Texas, Austin in 2006. She worked for a variety of non-profits in the Austin area until going back to school at Austin Community College where she earned a certificate in Environmental Science and Technology. Afterwards, she pursued internships and employment with various botanical and environmental organizations. She entered the Biology Master’s program at Texas State University in 2016, in Dr. David Lemke’s lab, to further her botanical studies.


DISSERTATION DEFENSE

ECOPHYSIOLOGY AND FOOD WEB DYNAMICS OF SPRING ECOTONE COMMUNITIES IN THE EDWARDS AQUIFER, USA


Name: Parvathi Nair

Major Advisor: Dr. Weston Nowlin, Department of Biology, Texas State University             

Committee Members: Dr. Benjamin Schwartz, Department of Biology, Texas State University

                                  Dr. Thom Hardy, Department of Biology, Texas State University

                                  Dr. Benjamin Hutchins, EARDC, Texas State University

                                  Dr. Joe Tomasso, Auburn University

 

Thursday, June 27, 9:00 am, Freeman Aquatic Building, Room 130  


Spring orifices serves as ecotones between groundwaters and surface waters. Communities found within spring ecotones are composed of organisms from a variety of habitats, including epigean, hypogean, and crenic species. I examined the ecophysiology and trophic ecology of invertebrates that occur within spring ecotones of the Edwards Aquifer (Texas, USA). It is thought that organisms living in physicochemically stable spring ecotones should exhibit small tolerance ranges; however, previous experiments examining this are equivocal. I examined this hypothesis by investigating effects of elevated temperature and decreased dissolved oxygen on several riffle beetle species (Coleoptera: Elmidae), including two ecotone specialists. Ecotone-associated species exhibited stenothermal tolerance profiles when compared to surface species. I also examined resource use in invertebrate communities at two spring ecotones using stable isotopes of carbon (d13C) and nitrogen (d15N) and amino acid-specific stable isotopes (d13CAA). Spring ecotones contain trophically complex communities with substantial niche partitioning among species. I finally examined the hypothesis that organisms in resource poor subterranean habitats can withstand long periods of food shortages due to reduced metabolic rate. In addition, subterranean taxa should exhibit energy resource use patterns different from epigean counterparts when exposed to prolonged food deprivation periods. Previous studies have also hypothesized that subterranean organisms in systems with ample energy resources (such as guano caves or spring ecotones) may not exhibit reduced metabolic rates. I assessed metabolic and biochemical responses of a subterranean amphipod (Stygobromus pecki) that inhabits spring ecotones and compared these responses to their epigean relative. Results indicate that despite occupying relatively resource rich habitat, S. pecki exhibit lower metabolic rates and differential use of energy resources when compared to epigean relative. Cumulatively, this body of research provides critical and new information on the ecology and evolution of spring ecotone communities, which are among the least studied and poorly understood aquatic ecosystems.


 Bio:  Parvathi Nair was born in Kerala, India. She earned a M.S. in Environmental Science in 2013 from University of Houston Clear-Lake, TX.  She entered the Aquatic Resources Ph.D. program at Texas State University in 2014, in Dr. Weston Nowlin’s lab, to work on the conservation of endangered invertebrates in the Edward Aquifer.


Thesis Defense

THE ROLE OF IBR5-AtNRPB4 INTERACTION IN PLANT GROWTH AND DEVELOPMENT


Rohit Upendra Katti


Major Advisor: Dr. Nihal Dharmasiri, Department of Biology, Texas State University

  

Committee Members: Dr. Hong-Gu Kang, Department of Biology, Texas State University

                                    Dr. Sunethra Dharmasiri, Department of Biology, Texas State University

 

Tuesday, July 02, 10:00 am, Supple Science Building, Norris Room


  Auxin is a crucial plant hormone necessary for the regulation of growth and development in plants. It has been shown that Indole Butyric acid Response 5 (IBR5), which encodes a dual specificity phosphatase, is involved in the auxin signaling pathway. However, its exact molecular mechanism by which it regulates auxin signaling is not well understood.  In yeast two hybrid screen, IBR5 interacted with NRPB4, which is known to be an integral part of RNA Polymerase II complex. Previous studies on NRPB4 have shown that it is involved in thermotolerance in yeast. Preliminary work on NRPB4 shows that it physically interacts with IBR5 in-vitro confirming yeast two-hybrid result. Further analysis shows that the catalytic domain of IBR5 is important for the interaction with AtNRPB4. The biological relevance of IBR5-AtNRPB4 interaction is not yet clear, but both proteins have been shown to be linked to heat stress responses. Characterization of Arabidopsis nrpb4 mutants shows severe growth defects in hypocotyl elongation and root growth in response to high temperature Additionally, nrpb4 show defective auxin responses suggesting possible functional interaction between IBR5 and NRPB4. However, effort to demonstrate IBR5- NRPB4 interaction in vivo was not successful. Nevertheless, in-vitro interaction between IBR5- NRPB4 along with common defective phenotypes of nrpb4 and ibr5 mutants suggest a possible interaction between these two proteins.


 Bio: Rohit Upendra Katti was born in Bengaluru, India. He earned a MSc in Biotechnology from Bangalore University, Bengaluru, India. In 2017, he then joined the lab of Dr. Nihal and Sunethra Dharmasiri to pursue his M.S. Biology degree. After graduating with a M.S. in Biology at Texas State University, he will be pursuing a PhD at University of Georgia- Athens in Pharmaceutical and Biological Sciences Department.


Thesis Defense

AN ASSESSMENT OF THE STANDARD DETECTION METHOD FOR AN ELUSIVE SPECIES - THE DUNE SAGEBRUSH LIZARD (Sceloporus arenicolus)


Maxie Lu Kiehne


Major Advisor: Dr. Michael R.J. Forstner

Committee Members: Dr. Paul Crump and Dr. Joseph Veech

 

June 26, 2019, 8:00 a.m., Supple 153


   The Dunes Sagebrush Lizard (Sceloporus arenicolus) is a highly cryptic, habitat specialist that shows a preference for environments comprised of large dune complexes and dense arrays of shinnery oak (Quercus harvardii). This species occupies a narrow range in the Monahans Sandhills of Texas and the Mescalero Sands of New Mexico and like many habitat specialists, they are sensitive to disturbances within this environment. Conservation of this species relies upon precise assessments of the occurrence, abundance, and population trends for this lizard. The standard method for detecting the DSL, visual encounter surveys (VES), was utilized to estimate the probability of detection across sites that had varying degrees of reported suitability. The probability of detection, for S. arenicolus, was compared to two more commonly detected species, Uta stansburiana and Aspidoscelis marmoratus. The minimum number of surveys, needed to reliably detect these species, was calculated from detection estimates. A total of 1,135 individual lizards were recorded, 13 of which were S. arenicolus. Results of the study indicated that while VES may be suitable for many common species of lizards, it may not be the most beneficial method for accurately determining presence of rarer species of lizards (i.e. the DSL). This could indicate that a more robust survey methodology (i.e. pitfall traps) may be needed when trying to make reliable occupancy or abundance estimates.  


Bio: Maxie was born in Midland, Texas and raised in Datil, NM. She graduated from Eastern New Mexico University, in 2017, with a B.S. in Wildlife and Fisheries Biology. Her passion for herpetofaunal species developed early in her undergraduate program and led to her pursuit of a M.S. degree. In 2017, she was accepted into the Wildlife Ecology program at Texas State University, under the guidance of Dr. Forstner. Before eventually pursuing a Ph.D., Maxie has decided work for non-profit organization in Carlsbad, NM, whose main focus is the development of environmental conservation programs.  


Thesis Defense


SPATIAL AND TEMPORAL USE OF CAVES BY ELEUTHERODACTYLUS MARNOCKII AND CRAUGASTOR AUGUSTI IN THE WESTERN EDWARDS PLATEAU OF CENTRAL TEXAS


 

William “Grady” Terry

 

Advisor: Dr. James Ott and Dr. Joseph Veech            

Committee Member: Dr. Ivan Castro-Arellano

Tuesday, June 25, 2019, 10 AM, Norris Conference Room


Understanding the spatial and temporal habitat associations of rarely encountered species is an important component of understanding their ecology. Barking frogs (Craugastor augusti) and Cliff-chirping frogs (Eleutherodactylus marnockii) are rarely encountered inhabitants of the rugged limestone terrain of the western Edwards Plateau of Texas. In order to explore the mechanisms of co-occurrence between these two species in a spatially restricted environment, I examined the habitat-use and dispersion patterns within and between these species. Six caves varying in length from 6 to 120 m were surveyed monthly from January through December 2017. Additionally, one cave was also surveyed at 6 h intervals across a 24 h period, quarterly. The locations of individuals with respect to cave entrance were recorded during each survey. Caves were used continuously rather than as temporary daily or seasonal refugia. Both species were present day and night throughout the year with peak abundance observed during spring-summer and summer-fall for E. marnockii and C. augusti respectively. Cave occupancy was not restricted spatially or temporally during the 24 h period or seasonally. Both species were found throughout the entire length of each cave but differed in patterns of microhabitat use. Individuals of C. augusti used elevated open faces greater than expected, while E. marnockii used this microhabitat less than expected. Eleutherodactylus marnockii exhibited seasonal patterns of intraspecific aggregation within caves whereas C. augusti did not. However, nearest-neighbor distances consistently failed to reveal evidence of interspecific repulsion or aggregation. The sole exception was that during peak abundance of C. augusti, E. marnockii displayed a repulsed pattern of dispersion away from the larger-bodied C. augusti. This repulsion may be a predator-avoidance behavior. This study is a primer to further investigations into the ecological interactions between these two ecologically specialized anurans.  


Bio: Grady was born and raised in central Texas. He earned his B.S. in Wildlife Biology at Texas State University during 2015 and spent the next year working various field biology jobs. He was accepted into the Texas State Biology Graduate Program in the fall of 2016 working with Dr. Ott and Dr. Veech to mentor his research. Upon graduation, Grady plans to continue working as a field biologist for a consulting firm.


Dissertation Defense

A CONSIDERATION INTO WAYS BIOLOGY-BASED student ORGaNIZATIONS FACILITATE PARTICIPATION IN STEM

 


 

Zachary L Nolen


Major Advisor: Dr. Kristy L Daniel  

 

Committee Members:  Dr. Carrie Bucklin, Dr. Ivan Castro-Arellano, Dr. Eleanor Close, and Dr. Paula Williamson

 

Wednesday, June 26, 2019, 11:00AM, Supple 257


Abstract: Over the past decade, there has been a strong push for ways of increasing the leaky STEM pipeline that results in students leaving STEM fields. Researchers speculate that one reason students leave STEM is because students have not developed a strong perceived attachment to the field of science. One way that students may build this perceived attachment to science is through participation in science-based social organizations. The purpose of my study was to investigate how biology-based student organizations functioned as affinity groups and how these groups influenced individuals’ perceived cohesion to science. I followed three biology-based student organizations, Biological Honor Society, Microbiology Club, and Wildlife Club, over the course of one academic year to identify the extent they exhibited the characteristics of affinity groups. After collecting and analyzing data from field observations, I found that all three groups exhibited the criteria of affinity groups to various degrees. Through analyzing student responses to an open-ended questionnaire, I was able to uncover the motivations students had for joining their respective student organizations and what benefits they reported receiving from their participation. I found three major overarching themes for what motivated students to join their respective student organization: they liked the content the organization was based on, to meet some form of social need, or the reputation of the organization drew them into the organization. Students reported a wide range of benefits they received form their participation in these organizations. I grouped these benefits into five overarching themes: Networking, Professional Development, Learning Opportunities, Community Involvement, and Prestige. I found that there was some overlap between students’ motivations for joining their student organization and what benefit they received from their participation. With this overlap, I speculate that a feedback loop exists where students join an organization for a specific reason that guides what events they choose to participate in which then leads into the benefit they receive from their participation. Now that we better understand how these organizations function, what motivates students to join content-based student organizations, and what they are getting from their experiences, we can further promote these groups to new students. By joining a content-based student organization, students will be better able to find their place in science through networking with others in their field and honing and developing skills that they can take into the workforce, ultimately making them more competitive on the job market.   


Bio: Zach was born and raised in central Alabama. He earned his B.S. in Biology from the University of North Alabama in Florence, Alabama and his M.S. in Biology from the University of Alabama at Birmingham in 2014. He began studying under Dr. Kristy Daniel at the University of Southern Mississippi in 2014 before transferring with her to Texas State University where he joined the Aquatic Resources program. Upon completing his doctoral degree, Zach plans to pursue his passion for teaching at the university level and help shape the next generation of scientists.


Dissertation Defense


UNDERSTANDING WIND ENERGY IMPACTS ON BATS AND TESTING REDUCTION STRATEGIES IN SOUTH TEXAS


 

Sara P. Weaver


Major Advisor:   Dr. Ivan Castro-Arellano

Committee Members:  Drs. Thomas R. Simpson, M. Clay Green, Cris D. Hein, & Amanda M. Hale

Thursday, June 20, 2019 10:00 AM, Ingram Hall, room 3204

 


Abstract: Impacts from burning of fossil fuels, including climate change, are promoting an increase in development of renewable energy alternatives. In response, wind energy development is expanding at an exponential rate across the globe. However, wind energy development has long been known to directly impact bats, which incur fatalities at wind turbines when struck by moving turbine blades. In the U.S., Texas is the leading producer of wind energy with >13,300 commercially operating wind turbines while also having the greatest diversity of bats. Despite this, research in Texas on this topic is lacking with only a few wind energy facilities producing publicly available or peer-reviewed data. In this dissertation, I conducted one of the first comprehensive studies on wind energy impacts on bats at the Los Vientos Wind Energy Facility in Starr County, Texas, part of the Lower Rio Grande Valley. Using a novel fatality estimator, I estimated the bat fatality rate by megawatt (MW) and per turbine, and found a moderate to high fatality rate, in which Brazilian free-tailed bats (Tadarida brasiliensis) were the most impacted species. I also studied bat acoustic activity at wind turbines in relationship to weather covariates and fatalities to further our knowledge of conditions that potentially increase susceptibility to turbine strikes. My results revealed specific climatic and temporal conditions during which bats are most active at wind turbines, as well as a relationship between activity and fatality, thereby informing on conditions in which bats are more susceptibility to fatality. Finally, I tested efficacy of a novel ultrasonic acoustic deterrent system to reduce bat fatalities at wind turbines. Results of this study indicate this technology is a promising tool for fatality reductions, and was one of the most successful field trials using acoustic deterrents in the world. Studies investigating wind energy impacts to bats are extremely relevant and necessary for conservation of impacted species, informing policy, and guiding wind energy development. Moreover, developing regional and site specific impact reduction strategies are important conservation actions. Results of my studies can be used to develop such strategies in other data deficient regions with similar climates and bat species such as the southwestern U.S. and northern Mexico, and applications of the acoustic deterrent technology I tested are global in reach.


Bio: Sara was born and raised in Carrollton, Texas. She graduated summa cum laude with her B.S. in Biology from Texas State University in 2009. She then went on to complete her M.S. in Wildlife Ecology in August 2012 while studying overwintering populations of Brazilian free-tailed bats in central Texas. After working as an environmental consultant for several years, she returned to complete her PhD in August 2015. In addition to her doctoral research, she currently works as a full-time biology lecturer at Texas A&M University-San Antonio (A&M-SA). Her decision to return for a PhD was due to her desire to become a tenure-track professor at A&M-SA once she graduates, and create a Wildlife and Fisheries degree program.

 


Dissertation Defense

 

 


Re-Evaluating the Reproductive Ecology of the Endangered Houston Toad (BUFO [=Anaxyrus] HOUSTONENSIS) using Automated Audio monitoring techniques

 

 


 

Andrew R. MacLaren
Major Advisor: Dr. Michael R.J. Forstner   

Committee Members:  Drs. Ben M. Bolker, Shawn F. McCracken, J. Andrew Royle, & Floyd W. Weckerly.

Wednesday, May 29, 2019, 9:00AM, Supple 257


Abstract: The Houston Toad (Bufo [=Anaxyrus] houstonensis) is a diminutive species of toad endemic to the gulf coastal and east-central sand counties of Texas. The species has been in perpetual decline since being described in 1956. In 1970 it was granted status as federally endangered. There has been sustained interest in recovering this species over the last 5 decades, and my dissertation sought to apply technological innovations towards improving our approach to monitoring for this species long-term. I utilized automated audio recording devices to collect data from potential breeding locations for this species from 2014-2018, but archives of these data date back to 2010. I used automated detection software to develop a recognizer for the distinct call that male Houston Toads produce. This enabled me to re-evaluate the daily and seasonal activity of the Houston Toad from multiple locations throughout its current geographic distribution. I found that temperature and humidity are the most influential abiotic environmental variables that influence chorusing behavior. I monitored locations with the greatest abundance of toads continuously from years 2015-2018, and utilized these data to assess the limitations of repeat aural surveys for this species. I tested the influence of both survey length and survey number on the probability of detection, along with investigating whether selecting against environmental thresholds improved detection overall. I found that the current suggested minimum number of annual surveys (11) is too few, even for surveys of increased duration. In a separate study I evaluated the landscape induced heterogeneity in detection probability and found that surveys conducted through forested areas are likely ineffective, and suggest surveyors minimize the distance between chorusing locations and survey points whenever possible. Finally, I evaluated the voice and general morphology of the Houston Toad relative to its nearest related congener the Dwarf American Toad (B. americanus charlesmithi). I found that once preserved these species are physically indistinguishable. The calls of each species varied widely by dominant frequency, both among and within species. Each of these studies provide information that is critical to improving the approach and outcome of long term and range wide monitoring for this critically endangered species.


Bio: Andrew grew up around the towns of Bay City, Michigan and Houston, Texas. He received his B.S. in Biology from Texas State University in 2013, and after a short hiatus returned to pursue a Masters, and ultimately a PhD. Andrew has been a lifelong musician, and builds electric guitars and basses in his sparse free-time. It is his affinity for music, and all things that make noise, that enabled him to flourish in his dissertation research studying the songs of frogs and toads.

 


Dissertation Defense
DETERMINING THE STATUS AND DISTRIBUTIONOF THE EASTERN BLACK RAIL (LATERALLUS JAMAICENSIS)IN COASTAL TEXAS

 


Amanda A. Haverland


Major Advisors: Dr. Floyd Weckerly & M. Clay Green  

Committee Members: Dr. Thom Hardy, Dr. Chris Butler, & Dr. Paul Leberg

 

Friday, May 3, 2019, 8:30AM, Ingram Hall 3204


Abstract: The black rail (Laterallus jamaicensis) is a small and secretive marsh bird that inhabits coastal high marshes and freshwater wetlands throughout the Americas and is a species of conservation concern. In Texas, winter migrant and breeding populations of the eastern black rail (L. j. jamaicensis) are known to occur in disjunct wetlands along the Gulf Coast. Black rail distribution and life history, however, are poorly studied in Texas. I studied the spatial ecology and habitat requirements of black rails in marshes of the Texas Gulf Coast from 2015 to 2018. Through the application of occupancy models, radio telemetry, capture-recapture studies, and a geographic information system, I provide an evaluation of factors that influence the distribution of black rails at multiple spatial scales in coastal Texas. Using occupancy data, I developed a species distribution model for the black rail in coastal Texas to identify important areas for the bird on a landscape-scale. I found positive associations between black rail occurrence and average annual precipitation as well as herbaceous vegetation density. Using radio telemetry, I tracked individual black rails during winter to estimate home range size and examine habitat associations at the home-range scale. I also looked at effects of disturbance from prescribed fire within black rail habitats. Prescribed fire is a common method used to manage the coastal marshes inhabited by black rails. My studies provide information that is crucial for beginning to understand black rail distribution in coastal Texas as well as for managing habitat for the species.


Bio: Amanda was born and raised in the suburbs of Chicago where she fell in love with the forest, nature, and especially birds. After obtaining a bachelor’s degree in art & technology, she switched gears to follow a passion for wildlife and moved to San Marcos to peruse a graduate degree at Texas State in wildlife ecology. Since then, it’s been an amazing and challenging 7-year journey from masters to PhD and she will miss being a grad student (sort of), but she’s finally ready to fledge.   


Dissertation Defense

DETERMINING THE STATUS AND DISTRIBUTION

OF THE EASTERN BLACK RAIL (LATERALLUS JAMAICENSIS)

IN COASTAL TEXAS


Amanda A. Haverland


Major Advisors: Dr. Floyd Weckerly & M. Clay Green  

Committee Members: Dr. Thom Hardy, Dr. Chris Butler, & Dr. Paul Leberg

 

Friday, May 3, 2019, 8:30AM, Ingram Hall 3204


Abstract: The black rail (Laterallus jamaicensis) is a small and secretive marsh bird that inhabits coastal high marshes and freshwater wetlands throughout the Americas and is a species of conservation concern. In Texas, winter migrant and breeding populations of the eastern black rail (L. j. jamaicensis) are known to occur in disjunct wetlands along the Gulf Coast. Black rail distribution and life history, however, are poorly studied in Texas. I studied the spatial ecology and habitat requirements of black rails in marshes of the Texas Gulf Coast from 2015 to 2018. Through the application of occupancy models, radio telemetry, capture-recapture studies, and a geographic information system, I provide an evaluation of factors that influence the distribution of black rails at multiple spatial scales in coastal Texas. Using occupancy data, I developed a species distribution model for the black rail in coastal Texas to identify important areas for the bird on a landscape-scale. I found positive associations between black rail occurrence and average annual precipitation as well as herbaceous vegetation density. Using radio telemetry, I tracked individual black rails during winter to estimate home range size and examine habitat associations at the home-range scale. I also looked at effects of disturbance from prescribed fire within black rail habitats. Prescribed fire is a common method used to manage the coastal marshes inhabited by black rails. My studies provide information that is crucial for beginning to understand black rail distribution in coastal Texas as well as for managing habitat for the species.


Bio: Amanda was born and raised in the suburbs of Chicago where she fell in love with the forest, nature, and especially birds. After obtaining a bachelor’s degree in art & technology, she switched gears to follow a passion for wildlife and moved to San Marcos to peruse a graduate degree at Texas State in wildlife ecology. Since then, it’s been an amazing and challenging 7-year journey from masters to PhD and she will miss being a grad student (sort of), but she’s finally ready to fledge.   


 

Thesis Defense

Elk population dynamics when carrying capacities vary across and within herds


Lisa Koetk


Major Advisor: Dr. Floyd Weckerly  

Committee Members: Dr. Adam Duarte & Dr. Todd Swannack

 

Wednesday, April 17, 2019, 8:30 AM, Ingram Hall 4102


Abstract: Variation in carrying capacity (K) across and within populations should impact population dynamics and stability. I fit linear regressions using Bayesian statistics to seven time series of population survey data of elk (Cervus elaphus). I explored the effects of variation in K across herds (i.e., populations) and temporal variation in rmax and strength of density dependence within herds at a landscape scale. I also estimated stochastic fluctuations in abundance around K for each herd. I checked for biases from observer error by comparing the results of the regressions to state-space Ricker models fit to the same time series. The regressions were likely not biased much by observer error due to accurate survey methods. My results indicate that rmax was similar across herds due to similar life history traits, while K and strength of density dependence varied across herds. Also, rmax and strength of density dependence varied temporally within herds. Variation in rmax is traditionally viewed as being generated from density-independent factors such as climatic variables, but the variation might also be generated from individual movement. I also found that herds with smaller K will have stronger density dependence, higher temporal variation in the strength of density dependence within herds, and less fluctuation in abundances around K. These results have implications for population conservation and land management, especially in the face of ongoing environmental changes which might affect population stability.


 Bio: Lisa grew up in Redmond, Washington. She graduated from St. Olaf College in Northfield, Minnesota, in 2016 with a B.A. in Biology. She then received a Fulbright grant to conducted research in India, where she studied the diets of livestock and wild herbivores in high elevation alpine meadows of the Himalayas. She will be beginning a Ph.D. program in the fall at the University of Northern British Columbia, where her dissertation will be focused on moose foraging and movement ecology after a mountain pine beetle outbreak.


Thesis Defense

 Interaction of IBR5 And Small GTP-BINDING Proteins in Groth and Development of Arabidopsis   


Idrees Ahmad


Major Advisor: Dr. Nihal Dharmasiri   

Committee Members: Dr. Sunethra Dharmasiri, Dr. Hong-Gu Kang & Dr. Ratnayaka

                          

Tuesday, April 9, 6:00 PM Norris Room


 Auxin is a plant hormone that regulates plant growth and development. Auxin controls the expression of auxin-responsive genes by regulating the degradation of a group of transcriptional repressor proteins known as Aux/IAAs (AUXIN/INDOLE-3-ACETIC ACID) via the ubiquitin-proteasome pathway involving nuclear auxin receptors. Recent studies have demonstrated that a dual-specificity phosphatase, INDOLE 3 BUTYRIC ACID RESPONSE5 (IBR5) is involved in auxin signaling. Previous studies indicate that several GTP binding proteins regulate auxin responses in plants.  The aim of this study was to uncover the role of the interaction between IBR5 and small GTP binding proteins in auxin signaling using biochemical and genetic analysis. According to our yeast two-hybrid screen, in vitro binding assays, and co-immunoprecipitation studies, IBR5 physically interacts with several small GTP binding proteins. To analyze genetic interaction double mutants were generated between ibr5 mutants and several mutants of small G proteins in Arabidopsis.  Results  indicate that ibr5,small G proteins  double mutants exhibit altered growth patterning of epidermal cells s when compared to wild-type  or single mutants. At least one Small G protein mutant suppresses the auxin insensitive phenotype of ibr5-4 suggesting that interaction between these small G proteins and IBR5 play an important role in plant auxin response. 


Bio:  Idrees Ahmad was born and raised in Philadelphia, PA and attended Central High school. He had a strong desire to pursue Biology and eventually completed his undergraduate degree in Biology at Xavier University of Louisiana in 2016. He later joined the lab of Dr. Nihal and Sunethra Dharmasiri at Texas State University to pursue his M.S degree. After completion of his M.S he is interested in pursuing jobs in the agritech industry.


Thesis Defense

Molecular analysis of Haemogregarinidae in freshwater turtles


Stephanie C. Nordmeyer


Major Advisor: Dr. Dittmar Hahn

Committee Members:

Dr. David Rodriguez, Texas State University

Dr. Michael Forstner, Texas State University

 

Tuesday, April 9, 2019 5.00 PM, IGRM 4104


Habitat fragmentation and other environmental stressors are major factors in declines of biodiversity and can impact threatened animal populations. To aid in conservation efforts, individuals from affected animal populations are sometimes removed from at-risk areas to be bred in captivity, after which the resulting offspring are released back into the environment. This strategy is commonly applied in conservation efforts on turtle populations. These turtles are often stressed, and consequently are more susceptible to diseases and parasites. In addition, captive propagation can increase the risk of disease or parasite transmission due to high density propagation and transport. In freshwater turtles, parasites are specifically represented by members of the Haemogregarinidae. Three genera, Haemogregarina, Hemolivia and Hepatozoon, are the most common parasites found in turtles. We determined the prevalence of these parasites in different freshwater turtles and tested for host-parasite associations. Samples were collected from eight different locations, and classified as Wild, Captive, or Wild Caught Captive Raised which comprised of 326 blood samples from six turtle families. SybrGreen-based qPCR detected Haemogregarinidae in 88 of these samples. 53% of individuals belonging to the Bataguridae, 26% belonging to the Emydinae and 23% belonging to the Kinosternidae were infected. No infections were detected in members of the Chelidae, Pelomedusidae, and Trionychidae. Comparative sequence analyses of PCR products indicated preference of parasites from the genus Hepatozoon for the Bataguridae, and those from the genus Haemogregarina to the Emydinae. Infections of single individuals by other genera were generally related to transport phenomena or captivity status, and therefore potentially artifacts.


Stephanie was born in Austin, Texas. She graduated from Texas State University in 2017 with a B.S. in Microbiology. After completing her M.S. in Biology, she will attend the University of Texas Health and Science Center in pursuit of her PhD.


Thesis Defense

Stormwater and Non-Point Source Pollutants in Sessom Creek, San Marcos, TX


Dalila Jazmin Loiacomo


Major Advisor: Dr. Benjamin Schwartz - Texas State University and Edwards Aquifer Research and Data Center.

Committee Members: Dr. Weston Nowlin - Texas State University & Dr. Thom Hardy | Texas State University

Tuesday, April 9, 2019, 1:00 PM, Freeman Aquatic Biology Building 130

 The primary goal of this project was to evaluate and model the transport (timing and amounts) of non-point source pollutants (NPS) from the Sessom Creek watershed into the Upper San Marcos River (San Marcos, Texas) during storm events. Sessom Creek is a small and heavily urbanized tributary of the Upper San Marcos River, a spring-fed river from the Edwards Aquifer. Runoff is extremely rapid in the high-gradient Sessom Creek watershed, and there are no significant stormwater retention or detention structures in the watershed. Therefore, rapid transport and loading of contaminants from Sessom Creek into the San Marcos River occurs during storm events. This is a concern due to the presence of several federally endangered or threatened species in the river, and its heavy recreational use. Twelve storm events were sampled during 2018 with an ISCO automatic sampler. NPS pollutants, including total/volatile/non-volatile suspended solids, nutrients (dissolved and total forms of nitrogen and phosphorous), and bacteria (E. coli) were analyzed in all samples using standard methods. Results indicate that transport and loading of stormwater pollutants to the river are highly variable and primarily dependent on the peak flow, maximum rain intensity, and antecedent rain. Increases in discharge and peak flow can occur within 5 minutes of rain. Most of the load is transported during the first hour of a storm event, and peak concentrations of pollutants often occur before the peak flow for each event, suggesting that remediation efforts should focus on detention and retention to avoid transport during the first flush portion of the hydrograph.


Bio: Dalila was born in Buenos Aires, Argentina and was raised in Boconó, Venezuela. She moved back to Argentina to study Environmental Science, where she participated in a project to study the impacts of industrial agriculture in water. In 2013, she studied abroad at the University of Sao Paulo, Brazil, where she took more water-related courses and learned a new culture. She graduated from her BS in 2016, her passion for water brought her to study her MS at Texas State University. Currently, she is looking for new opportunities to work on the protection and sustainable management of water resources


Thesis Defense

The Role of IBR5 in Regulating Plant Auxin Response Through the SCFTIR1/AFBs Complex


Timothy J. Cioffi
Major Advisor: Dr. Nihal Dharmasiri - Texas State University, Department of Biology

Committee Members: Dr. Sunethra Dharmasiri - Texas State University, Department of Biology & Dr. Hong-Gu Kang - Texas State University, Department of Biology

 

Monday, April 8, 2019, 5:30 PM, Supple Science Building 112


Plant growth and development is a highly regulated process that involves synthesis, cellular transport, and perception of the growth hormone indole-3-acetic acid (IAA). Cellular responses to auxin involve the degradation of the Aux/IAA family of repressors through SCFTIR1/AFBs complex, which is composed of ASK1, CUL1, RBX1, and the F-box protein TIR1/AFBs, subsequently modulating the expression of auxin-related genes to control growth and development. Previous studies identified IBR5 as a gene involved in the auxin response pathway, as primary root growth of ibr5 mutants exhibited insensitivity to indole-3-butyric acid (IBA), a precursor to IAA in plants, as well as IAA and other auxin analogues. Additionally, ibr5 is defective in several other hormone and stress response pathways. Interestingly, Aux/IAAs are rapidly degraded in ibr5 mutants, which is contrary to other mutant genes identified in the auxin signaling pathway. This research sought to characterize the role of  IBR5 in regulating the auxin response pathway. Previous results indicated that SCFTIR1/AFBs subunit, ASK1, interacts in vitro with IBR5.  Results of this research indicate that steady state levels of ASK1 and TIR1 proteins are subjected to modulation in ibr5 mutant and 35S:IBR5-Myc overexpression lines, suggesting direct or indirect regulation of these SCF components by IBR5. Since SGT1b is also known to regulate TIR1 abundance, the genetic interaction between IBR5 and SGT1b was also analyzed. ibr5, sgt1b double mutants show increased auxin resistance compared to single mutants. Collectively, findings in this study suggest that IBR5 may be involved in proper subcellular localization of TIR1 through an unknown mechanism.


Bio: Tim was born in Grapevine, TX, where he grew up, and was involved in Drumline before he graduated from Colleyville Heritage High School in 2010. He later attended Texas State University, performing undergraduate research under Dr. Jim Ott, and graduated with a B.S. in Biology in 2016. After graduating with a M.S. in Biology at Texas State University he will be pursuing a PhD at Indiana University – Bloomington in Genome, Cell, and Developmental Biology.


Thesis Defense

Perceptions of Principals in a Science and Mathematics Professional

Development Program


Sara M. Hanson

Major Advisor: Dr. Sandra West, Texas State University

Committee Members: Dr. Julie Westerlund, Texas State University, Dr. Emily Summers, Texas State University, Dr. Sandra Browning, University of Houston-Clear Lake

 

Monday, April 8th, 4:00 pm, Supple 257

 


The need for qualified individuals to fill positions in science, technology, engineering, and mathematics (STEM) careers has increased the attention on STEM education over the last decade. Therefore, a greater need exists than ever to ensure that students have a deeper understanding of science and mathematics. The available literature emphasizes the need for quality science and mathematics education, specifically the integration of science and mathematics in the classroom. Professional development can be utilized to better enable teachers to employ best practices in their science and mathematics teaching. However, effective professional development must adhere to best practices. Moreover, studies have shown that teachers are more likely to utilize learning from professional development and more effectively implement strategies and approaches gained during attendance if they have the support of their principal. My study aimed to find teacher and principal perceptions of a science and mathematics leader and the support that they provide their teachers when attending a science and mathematics-specific professional development program. I used a mixed-methods approach to answer my research questions. My results showed that teachers and principals identified common qualities and behaviors in principals that support teachers’ science and mathematics instruction. The principal characteristics identified by participants were many of the same qualities and behaviors described by the professional development program to enhance teachers’ science and mathematics instruction. Further studies would need to be conducted to confirm the results of my study before making recommendations. However, once additional studies have been conducted, recommendations could potentially be made to involve principals more in science and mathematics-specific professional development with their teachers in order to enable principals to have a better understanding of what quality science and mathematics support is and how it can best be supported by principals.


Bio: Sara was born in Dallas, TX and raised in Austin. She graduated from Texas State University in 2008 with a B.S. in Bilingual Elementary Education. After teaching 3rd and 4th grade in Austin ISD for seven years, she decided to pursue an M.S.I.S. in Interdisciplinary Studies with a concentration in Science, Mathematics, and Technology Education for Elementary and Middle School Teachers. She returned to the classroom as a 4th grade mathematics and science teacher in the fall of 2018.


 

Thesis Defense

 Rumen-reticulum organ mass and rumen mucosa surface area of white-tailed deer

(Odocoileus virginianus) consuming two diets 


 

Sterling Spilinek


Major Advisor: Dr. Floyd Weckerly

Committee Members:

Dr. Ivan Castro-Arellano, Texas State University

Dr. M. Clay Green, Texas State University

 

Friday, April 5, 2019 11:00 AM, Bruce and Gloria Ingram Hall 3204


Abstract: Ungulate diets display spatial and temporal variation. To accommodate dietary variation, elasticity, organ mass, and absorptive capacity presumably change in the rumen-reticulum. The gastrointestinal organs with most of the capacity and where most digestion occurs. I measured rumen-reticulum organ mass and absorptive capacity in white-tailed deer (Odocoileus virginianus) collected at Kerr Wildlife Management Area, Texas. I hypothesized that nutrient poor diets would result in greater mass-specific food intake because of low nutrient concentrations. The consequence would be heavy rumen-reticulum organs and low absorptive capacity. Since weaning, deer were fed a pelleted diet, ad libitum, of 1.77 or 2.67 kcal/gm digestible energy. In December 2017, 4.5- and 5.5-year-old deer were euthanized, the rumen-reticulum was extracted, thoroughly rinsed, rung out, and weighted. Four, 1 x 3 cm samples were cut from four regions of the rumen. The samples were fixed in ExCell plusTM for 24 hours, then preserved in 70% ethanol until measured. For each 1 cm2 sample, I measured length and width of 10 randomly selected papillae, counted papillae density, and calculated a surface enlargement factor (SEF). My surrogate of food intake was first molar height measured on the right side of the jaw. Diet consumed by deer was unbeknownst to the measurer. Analyses of general linear models indicated that deer consuming the low energy diet had higher food intake, heavier rumen-reticulum organs, and lower SEF than deer consuming the higher energy diet. White-tailed deer adjust rumen-reticulum morphology to maintain digestive functions when diets vary in energy content.  


 Bio: Sterling was born and raised in Douglas Wyoming. He graduated from Whitman College in 2014 with a B.A. in Biology. After completing his M.S. at Texas State University, he is planning to move back to the rocky mountain region in pursuit of a job.


Thesis Defense

 

EFFECTS OF COBALT ON CHROMOBACTERIUM VIOLACEUM QUORUM SIGNALING IN THE ABSENCE AND PRESENCE OF OXYGEN


Name: Sahar Kianarsi


Major Advisor: Dr. Robert JC McLean- Texas State University, Department of Biology

 

Committee Members: Dr. Manish Kumar- Texas State University, Department of Biology

                                    Dr. Karen Lewis- Texas State University, Department of Chemistry and Biochemistry

 

 

Friday, April 5, 2019, 10:00 AM, Ingram 3207

 


 Bacteria exist as colonial organisms, that utilize signaling system for communication. Quorum signaling is a cell-density dependent cell-to-cell bacterial communication which regulates several phenotypes such as biofilm formation, pigmentation, and virulence. Chromobacterium violaceum is a gram-negative, facultative anaerobic bacterium dwelling in the soil and water of tropical environments. Quorum signaling is responsible of the C. violaceum biofilm formation and violacein production, deep purple pigment. Several biological and organic molecules have been identified as quorum signaling inhibitors. Previous research showed that sub-lethal concentrations of heavy metals such as cadmium and nickel inhibited C. violaceum quorum signaling. These inhibitory effects of heavy metal divalent cations were shown in violacein production, virulence, biofilm formation, and  gene expression. In this study, we showed that cobalt inhibited floc biofilm formation in both aerobic and anaerobic conditions, but did not affect attached biofilm. This study is the first report of the effects of heavy metal on quorum signaling inhibition of C. violaceum in anaerobic condition.


 Bio: Sahar moved to US from Tehran, Iran, where she received her Bachelor in microbiology. In 2016, she joined the graduate program in Biology at Texas State University. After graduating wit


Thesis Defense

Influence of Surface and Near-surface Geology on Fish Assemblages

in the Colorado River basin of Texas


Peter J. Pfaff


Major Advisor:   Dr. Timothy H. Bonner, Department of Biology, Texas State University

Committee Members:  

Dr. Alan Groeger, Department of Biology, Texas State University

Dr. Benjamin Schwartz, Department of Biology, Texas State University

 

Tuesday, April 2, 2019, 2:00 PM, Freeman Aquatics Building, Room 130

 


Fish communities are distributed heterogeneously within river basins. This heterogeneity is attributed to a number of physical, chemical, and biological processes. Among river basins that traverse a diversity of geological strata, physical and chemical properties of geological strata influence stream characteristics and regional aquatic communities. Likewise, stream characteristics and aquatic communities of geological strata (i.e., georegions) can respond differently to anthropogenic stressors. Purposes of this study were to assess the influence of geological strata (i.e., georegions) on stream characteristics and fish communities in the Colorado River basin of Texas, a representative western gulf slope basin of southcentral USA, and determine if anthropogenic stressors differentially affect fish communities by georegion. Using measures of discrete (i.e., georegions, stream type) and continuous (e.g., stream order, distance from river mouth) community variation (i.e., spatial delineations), I found that georegion, stream type, stream order, and distance from mouth distinguished stream characteristic types within the basin, but only georegion explained a significant portion (41%) of the fish community variation. Using fish community changes between time periods (1933 to 1980; 1981 to 2017), which generally corresponds with pre- and post-dam constructions within the basin, I found that anthropogenic flow alterations had more of an effect on fish communities in some georegions than others. My findings support the concept of geological strata having a hierarchical influence on stream characteristics and aquatic community heterogeneity within a basin, and that anthropogenic modifications can differentially affect aquatic communities, depending on factors associated with geological strata (i.e., stream characteristics). Potential benefits of this work include understanding factors influencing the heterogeneity in aquatic communities and the role of anthropogenic stressors across georegions (e.g., prairie streams, karst terrains, lowland coastal rivers) within and outside the western gulf slope basins.


Bio: Peter was born in Seoul, South Korea but grew up in Kansas and Texas. After graduating from Lutheran South Academy in Houston Texas, he began his coursework at Concordia University Texas where he graduated cum laude with a degree in biology in 2009. Following graduation, he moved to Japan and worked as an English teacher and school manager. In 2016, Peter returned to Texas and entered the Graduate College at Texas State University-San Marcos in June the following year. 


Dissertation Defense


FOSSIL ANGIOSPERM WOODS FROM THE JOSE CREEK MEMBER OF THE MCRAE FORMATION

 

Joan M. Parrott

 

Co-Chairs: Dr. Paula Williamson and Dr. Garland Upchurch, Jr

 

Committee Members: Dr. Chris Nice, Dr. Lisa Boucher and Dr. Cindy Looy

 

Monday, April 1, 2019, 9:30 AM, SUPP 153

 


The Jose Creek Member of the McRae Formation, south-central New Mexico, preserves a diverse angiosperm flora of Late Campanian (76.5 to >72.5 Ma) age. The site is of special interest because it provides an abundance of fossil evidence in the form of leaves, reproductive structures, and silicified woods found in situ and as float. The wood flora is the third most diverse Cretaceous wood floras in the world. Approximately thirty-four species of non-monocot angiosperms have been discovered. Many of the McRae xylotypes are common elements in other Cretaceous wood assemblages. Most magnoliids represent Lauraceae (~seven wood types), a dominant element in modern Asian tropical and subtropical vegetation. Two genera (Agujoxylon and Metcalfeoxylon) with exclusively scalariform perforation plates co-occur in assemblages in the southwest of North America. Four xylotypes have a combination of exceptionally wide (>10 cells wide) and nearly homogeneous rays, features that characterize extant Platanus. The Platanus-like woods fall outside the generic limits for Platanoxylon, warranting a new genus. The Forest of Giants is an assemblage of exceptionally large angiosperm in situ stumps that represent a riparian forest preserved in a sequence of fluvial sandstones. The site is dominated by one species of Paraphyllanthoxylon with wood anatomical features that suggests affinity with the extant family Kirkiaceae. One McRae Paraphyllanthoxylon stump is the largest Cretaceous angiosperm stump yet recorded worldwide. Three individual stumps represent probable Lauraceae, Sapotaceae and Urticales (Rosales). Woods from the Forest of Giants add to a growing body of evidence from in situ assemblages for large angiosperm trees as dominants during the Late Cretaceous, especially in regions of warmer climate such as the southern Western Interior of North America.  Affinities of most woods with simple perforation plates are, as yet, unidentified. The McRae Formation flora will provide unique insight into the stature and diversification of angiosperms at a critical period in their radiation.


Bio: Joan is originally from the small farming community of Alice, North Dakota. She earned a B.A and an M.A from the University of Texas at Austin in 1979 and 1982, respectively, both in the Department of Botany.


Thesis Defense

Response of Unionid Mussels Density and Distribution to Extreme Climactic Events in the Big Thicket Ecoregion of Texas


Alison A. Tarter
Major Advisor: Dr. Astrid N. Schwalb

Committee Members: Dr. Thom Hardy and Clint Robertson

 

Thursday March 28, 2019, 1:30PM, FAB 130


   The Big Thicket ecoregion located in (South)east Texas harbors the highest number of regional endemic freshwater mussel species and the highest diversity of unionid mussel in the state, including 5 of the 14 state threatened species.  Unfortunately, mussels in this region are threatened by pollution, habitat alteration and destruction due to human impact caused by petrochemical activities, climatic changes and urbanization. The goals of this project were to (1) survey mussels in the Big Thicket National Preserve, particularly in the poorly surveyed southern portion of the preserve, and (2) to examine historical changes in mussel communities. In addition, DNA samples were taken and the analysis of 97 mussels informed identification of eleven species, some of which can be difficult to distinguish morphologically. A total of 39 sites in the Lower Neches River, Village Creek and Pine Island Bayou basins were surveyed. Historical data from 2014 were available for 13 of these sites and were used to examine the impact of extreme flooding in 2017 to different parts of the basin. Comparison with data from 2002 were restricted to 10 sites in the Village Creek sub-basin. The survey showed that species richness and mussel densities generally increased from upstream tributaries towards lower Village Creek and mainstem Neches, where rare and threatened species were mostly found. Evidence for recruitment was mostly found in the backwaters of the lower Neches, which may act as refugee during flooding.  Declines between 2014 and 2018 were most severe in parts of the Neches basin that most likely experienced the highest shear stress during flooding based on the channel morphology. Declines were also detected when data from 2002 were compared with 2014 suggesting that the exceptional drought in 2011 may have also contributed to long-term declines in Village Creek. Future studies should examine the role of backwaters for recruitment of threatened mussels.


Bio: Alison is from Bridge City, Texas, she earned her B.A. from Stephen F. Austin University in 1999 with a major in Photojournalism and a minor in Graphic Arts.  Alison’s hobbies fishing, travel, medieval battle reenactment, and playing roller derby.      


Dissertation Defense

Factors influencing community structure of riverine organisms:  implications for imperiled species management


 

David S. Ruppel


Major Advisor: Timothy H. Bonner, Department of Biology, Texas State University

Committee Members:  Noland H. Martin, Department of Biology, Texas State University, Kenneth Ostrand, U.S. Fish and Wildlife Service, San Marcos, Texas, Jim A. Stoeckel, School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Joseph A. Veech, Department of Biology, Texas State University

  

Tuesday, March 26, 2019, 2:00 PM, Freeman Aquatics Building, Room 102


Riverine environments are dynamic with numerous biophysical components influencing community structure of riverine biota.  Common theme among my dissertation chapters is the quantification of community structure related to biophysical components of riverine environments in an effort to identify mechanisms underlying community structure (e.g., species richness, species abundances, life history traits).  Communities within two Texas river basins (i.e., Red River drainage, Colorado River drainage) include several species identified as imperiled species, either federally or by states.  A goal for each chapter was to integrate patterns and processes of community structure with current efforts to list species under the Endangered Species Act or to mediate negative anthropogenic influences on species and communities.  Chapter 1 addressed gaps in life history information, current distribution, and habitat associations for the Red River Shiner, an endemic cyprinid in the Red River basin.  Information was used to estimate redundancy, resiliency, and representation of the Red River Shiner, following the framework of U.S. Fish and Wildlife Service in species status assessments and eventually listing decisions.  Chapter 2 tested three theories related to largescale migrations of prairie stream fishes, using the federal candidate for listing Prairie Chub as a model organism.  Chapter 3 was a fish community assessment of the upper Red River of Texas and Oklahoma and quantified historical to contemporary changes in occurrences and abundances of six species of greatest conservation need.  Chapter 4 was a mussel community assessment of the Colorado River basin that identified georegion, along with associated substrates, stream gradient, and water quality, as more powerful predicator of community structure than smaller scale mesohabitat characteristics.  Mechanisms of community structure are still elusive and in need of further investigation, but I was able to use a multiscale approach to advance the general understanding of processes influencing observed patterns among riverine biota.   


Bio: David was born in Saginaw, Michigan but lived in the quaint town of Ishpeming in Michigan’s upper peninsula for most his childhood. He graduated cum laude with his B.S. in Zoology from Northern Michigan University in 2012. David completed his M.S. in Aquatic Resources in August 2014 studying the effects of instream flow on larval fish diets in the San Antonio and Guadalupe Rivers. He began as a PhD student in 2015 and plans to complete his PhD in May 2019.  Long term goals include pursuing a tenure-track professor position at an accredited university and establish a laboratory that focuses on studying riverine community ecology. 


Thesis Defense

Intra- and Interspecies Variability in Mercury Concentrations in Texas Marine Fish and Shellfish


Kristyn D. Cunningham
Major Advisor: Dr. Jessica Dutton

Committee Members: Dr. Timothy Bonner and Dr. Weston Nowlin

 

Monday March 25, 2019, 2 PM, FAB 130


   Mercury (Hg) is a toxic nonessential trace element which can bioaccumulate in marine organisms and biomagnify up marine food webs, so top predators including tuna, swordfish, and sharks have the highest body burden. Humans are primarily exposed to Hg through seafood consumption. Fish in the Gulf of Mexico can have a higher Hg concentration than the same species in the connecting Atlantic Ocean, and all 5 states bordering the Gulf (TX, LA, MS, AL, and FL) have issued Hg advisories regarding fish consumption. This study investigated the concentration of Hg in 26 fish and 4 shellfish species (n = 1,468 samples) caught along the Texas coast during 2016 and 2017 using a Direct Mercury Analyzer and determined which species exceeded federal and state Hg advisory levels. The relationship between Hg concentration and body size was also examined for 26 of these species. Eighteen species, including king mackerel, red snapper, dolphinfish, red drum, and southern flounder had a positive relationship between Hg concentration and body length. One species, striped mullet, was found to have a negative relationship, suggesting that growth dilution was occurring. On average, Hg concentrations were highest in offshore fish species (e.g., blue marlin, cobia, sailfish, little tunny, and king mackerel), followed by nearshore fish species, and lowest in shellfish (e.g., blue crab, brown shrimp, and American oyster). Seven out of 12 offshore fish species had an average Hg concentration that exceeded the Texas Department of State Health Services (TDSHS) health-based standard of 0.7 µg/g wet wt, and three of these species (blue marlin, sailfish, king mackerel ) also exceeded the Food and Drug Administration (FDA) Hg action limit of 1 µg/g wet wt. With the exception of gafftopsail catfish, none of the examined nearshore fish species and shellfish had an average Hg concentration that exceeded the Environmental Protection Agency (EPA) Hg human health criterion of 0.3 µg/g wet wt, indicating that these species should be consumed if you want to limit your Hg exposure through seafood consumption.


Bio: Kristyn is from Marble Falls, Texas and earned her B.S. from Texas State University in 2016 with a major in Biology and minor in Chemistry. She enjoys collecting many types of cacti and her dream job is to work for Texas Parks and Wildlife.


Dissertation Defense


Predicting Future Range Expansion of Whooping Crane (Grus americana) Winter Habitat Using Long-Term Census and Remotely Sensed Data


Nicole A. Davis

 
Major Advisor: Dr. Thomas Hardy 

Committee Members: Dr. M. Clay Green, Dr. Jennifer Jensen, Dr. Susan Schwinning and Dr. Elizabeth Smith

Monday, March 11, 2019, 8:00, Freeman Aquatic Building #102


The whooping crane (Grus Americana; referred to as cranes) is one of the most threatened crane species in the world and has been identified as an endangered species since 1967.  The feasibility of meeting down-list objectives requires an assessment of space-use by cranes and of the amount of available habitat within the winter range to support the recovery goal population size.  Using a long-term dataset on the locations of wintering cranes, I analyzed space-use strategies of subadult (Immature), associated (non-mating pair), and paired/family (mating pair) cranes using home range and core area estimators, developed a distribution model for wintering cranes, and explored potential carrying capacity limitations of the current winter range using a rule-based simulation model.  I used location data for 42 color-banded cranes and kernel density estimators to identify the extent of winter home ranges and core areas.  The resulting home range and core area estimates yielded similar spatial distributions identified by U.S. Fish and Wildlife Service annual winter monitoring, and identified a positive relationship between core area size and land cover diversity.  I created winter crane distribution models using over 5,000 crane locations and combinations of 35 GIS-derived layers as environmental and ecological input in Maxent.  The most parsimonious model included 11 data layers that best described crane distribution within the winter grounds and identified 181,000 ha of highly suitable habitat that could support an exponentially growing crane population.  Using habitat suitability estimates from the crane distribution model, I developed a simulation model that mimics territory establishment by wintering cranes.  I then used the model to explore rules on territory development and winter carrying capacity estimates.  Overall, my results provide quantitative understanding of the distribution of wintering cranes and contributes to predicting future range expansion that will be required as the population increases towards down-listing goals.


Bio: Nicole A. Davis earned a B.S. in Biology from the University of Texas – San Antonio in 2007.  She decided to continue her education at Texas A&M University- Corpus Christi where she completed a M.S. in Biology in 2011 and continue as a research associate identifying priority locations for restoration and conservation efforts within the mid-Texas Coast.  As a Ph.D. student, Nicole continued her interests in research and conservation by participating in field studies for the endangered Whooping Crane and conducting habitat surveys using UAVs.


Thesis Defense

Invertebrate community structure and habitat associations in the arid Davis Mountains region of west Texas


Nina Noreika
Major Advisor: Dr. Weston Nowlin

Committee Members:

Dr. Astrid Schwalb, Texas State University

Dr. Benjamin Schwartz, Texas State University

Chad Norris, TPWD

 

Tuesday, February 19, 2019 8 AM, Freeman Aquatic Biology Building 130


Abstract: In arid regions, springs often represent ecologically important aquatic habitats which are patchily distributed across the landscape. This separation can lead to localized endemic populations of organisms that exhibit small species distributions and are adapted to local environmental conditions. Desert spring aquatic organisms are also frequently of high conservation priority and are listed as imperiled and in need of protection. This study examined invertebrate community structure and habitat associations at seven sites in and around the Davis Mountains in the Trans Pecos region of west Texas.  The overall purpose of this study was to determine mesohabitat associations and estimate population sizes of three endangered aquatic invertebrates found in the region: the Phantom springsnail (Pyrgulopsis texana), the Phantom tryonia (Tryonia cheatumi), and the diminutive amphipod (Gammarus hyalleloides). I conducted stratified random sampling at all sites quarterly for a year starting in March of 2017.  Results indicate that the abundance of most of the endangered species was most strongly influenced by site (the particular location that was sampled) and that mesohabitat conditions were substantially less important in influencing the density of species. In addition, I found that two species of non-native and invasive snails (Melanoides tuberculata and Tarebia granifera) were found at most of the study sites sometimes at densities higher than populations of native invertebrates. These results suggest that regionally distributed invertebrates with low dispersal potential (such as snails and amphipods with no desiccation-resistant life stages) exhibit high site-specific occurrence. In addition, these results indicate that conservation of these populations in the wild should focus on site-specific objectives to preserve water quality and habitat conditions.  However, this management strategy is complicated by the fact that these spring systems are interconnected by a larger regional groundwater pool.  With agricultural demands and oil and gas development increasing in the Trans-Pecos region, the risk for groundwater over-pumping and contamination place individual and collective regional populations at risk.


 Bio: Nina was born in northern Virginia and was raised in Newnan, Georgia. She graduated from Auburn University in 2015 with a BS in Organismal Biology: Ecology, Evolution, and Behavior. After completing her MS at Texas State University, she is moving to Prague to pursue her PhD in environmental engineering at Czech Technical University.

 


Thesis Defense


Using museum and citizen-science data to examine the range contraction of a threatened lizard species  


Jared Haney

 

Major Advisor: Dr. Joseph Veech            

Committee Members: Dr. Sarah Fritts, Dr. Chris Nice, Dr. Ivan Castro-Arellano

 

Wednesday, February 13, 2019, 1:00 PM, IGRM 4102

 


I assessed the utility of museum and citizen-science databases for observing range dynamics of a species that is suspected to have experienced a significant contraction in recent decades, the Texas horned lizard (Phrynosoma cornutum). By integrating spatial data from two sources, VertNet and iNaturalist, into a GIS computing environment and segregating observations into five time periods, I calculated several metrics to characterize the size and location of the P. cornutum range over time. These metrics were based on fitting a minimum convex polygon (MCP) to the lizard observations of each time period. I compared the location of the range edge for consecutive time periods so as to test whether the range has been contracting in each of the four cardinal directions as assessed by distances between the historic center and recorded lizard observations and the distances between the historic center and the range edge. The area of the geographic range declined 10% between historic and current time periods. All four ANOVAs (one for each quadrant) comparing mean distance of lizard observations to the historic center revealed statistically significant differences among the time periods (East, F4,462 = 66.5, P < 0.00001; West, F4,835 = 20.8, P < 0.00001; North, F4,927 = 81.4, P < 0.00001; South, F4,594 = 4.7, P = 0.0009). For mean distance to the edge, only the East (F4,81 = 5.0, P = 0.001) and South (F4,194 = 23.5, P < 0.00001) had significant differences among time periods. The eastern quadrant was the only quadrant to experience a steady decline in mean edge distance and mean observation distance from the historic to the current time period. The southern quadrant is characterized by small sample sizes and erratic patterns of change among time periods. Range size and edge location in the northern and western quadrants remained relatively stable over time. The main conclusion is that the eastern portion of the P. cornutum range has contracted between 1960 and 2017. The exact cause of the contraction remains unknown, although it could be indirectly related to increasing human population density and landscape alteration in the eastern part of the range. The use of citizen science and museum records provides a level of data collection necessary for monitoring broad-scale range dynamics. MCPs and derived metrics provide a straightforward approach for monitoring range dynamics, although they may sometimes be prone to overestimate range size and may not be informative for irregularly-shaped distributions or for rare species. The methods employed in my study could be applied to other species that may be undergoing range contraction or expansion.


Bio: Jared was born in Humble, Texas and went to the Woodlands High School. He attended the University of Texas at San Antonio and received his B.S. in Biology in 2013. After a trial run of grad school at UTSA, a year of travel and a period of self-reflection, Jared began his masters in Wildlife Ecology at Texas State University in 2017.


Dissertation Proposal Defense

 

The role of life history strategies and drying events for mussel communities: A

multiscale approach

 

 


Zachary Mitchell

 

Major Advisor: Dr. Astrid Schwalb Committee Members:

Dr. Thom Hardy, Texas State University

Dr. Todd Swannack, US Army ERDC Dr. Karl Cottenie, University of Guelph

Dr. Joshuah Perkin, Texas A&M University

 

Wednesday, February 6, 2019, 11AM, Freeman Aquatic Building 104

 


Abstract: Drying events, such as anthropogenic dewatering and drought, which are predicted to occur more often and with greater intensity due to global climate change, pose a great risk to stream organisms requiring perennial flow.

Freshwater mussels are particularly sensitive to drying events because they are relatively sessile and cannot easily escape disturbance events. Both drought and excessive water extraction pose a major threat in Texas. Therefore, the primary objective of this dissertation is to examine the role of drying events on mussel communities by using a multi- spatial, temporal and organizational scale approach. Chapter 1 investigates the role of life history strategies of mussels for the behavioral and physiological responses to drying events by utilizing lab experiments and a review of existing literature. Chapter 2 will examine how varying environmental conditions impact population dynamic rates of mussels with different life history strategies within three central Texas rivers using mark-recapture techniques. Chapter 3 will examine the role of life history strategies and other selective forces on mussel distribution and metacommunity structure along a longitudinal gradient of two central Texas rivers using spatial analyses of continuous survey and remotely sensed data. Chapter 4 examines long-term changes in mussel communities between two periods in four central Texas rivers in relation to a major drought event. Chapter 5 will provide a synthesis and attempt to develop a holistic conceptual model to predict the distribution and structure of mussel metacommunities in rivers subject to drying events based upon life history strategies and other selective forces.


Bio: Zach was born in Paris, Texas and raised in central Florida. He graduated from Mississippi State University in 2014 with a B.S. in Wildlife, Fisheries, and Aquaculture Science. Subsequently, he completed his master’s degree in 2016 at Eastern Illinois University in Biological Sciences focusing on fisheries management. He started his PhD here in 2016 in Aquatic Resources.


Dissertation Proposal Defense


UTILIZING MULTIDISICPINARY METHODS TO UNDERSTAND CONTAMINANT ACCUMULATION IN CETACEANS: CASE STUDIES IN THE GULF OF MEXICO AND NEW ZEALAND

 


Meaghan McCormack
Major Advisor: Dr. Jessica Dutton (Department of Biology – Texas State University)

 

Committee Members:

Dr. Weston Nowlin, Department of Biology - Texas State University Dr. Floyd Weckerly, Department of Biology - Texas State University Dr. Todd Swannack, Integrated Ecological Modeling US Army ERDC Dr. Aaron Roberts, Department of Biological Sciences - University of North Texas

Wednesday, November 28, 2018, 9:00 AM, Freeman Aquatic Biology 102

 

Cetaceans are long-lived top predators that can accumulate high concentrations of contaminants, including Hg, Cd, PCBs (polychlorinated biphenyls), and DDT (dichloro-diphenyl-trichloroethane) in their tissues. However, studying cetaceans can be difficult due to logistical and legal constraints. As a result of these challenges, contaminant studies are often limited by sample size and therefore a mixed methodological approach is the most effective way to advance our understanding of contaminant body burdens in cetaceans. My proposed research will use tissues, teeth, and computer modeling to understand the accumulation of contaminants in cetaceans from the Gulf of Mexico and New Zealand. The recent northern Gulf of Mexico (GoM) Cetacean Unusual Mortality Event (2010-2014) provided a unique opportunity to obtain tissue samples (e.g., skin, blubber, muscle, kidney, liver, and brain) from over 300 individual cetaceans [primarily bottlenose dolphins (Tursiops truncatus), but also less commonly sampled cetacean species] to assess the bioaccumulation patterns of essential (e.g., Cu, Se, Zn) and nonessential (e.g., As, Cd, Hg, Pb) trace elements in relation to body length/age, sex, food source (δ13C), trophic position (δ15N), and habitat (δ34S). Using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Scanning Electron Microscopy equipped with Energy Disrupting X-ray Spectroscopy (SEM-EDX) I will determine trace element concentrations in the annual growth layers of GoM bottlenose dolphin teeth to determine if changes in environmental exposure to trace elements can be reflected within an individual’s lifetime. Finally, I will incorporate organic pollutants into a previously developed computer model based on the behavioral interactions of dusky dolphins (Lagenorhynchus obscurus) and killer whales (Orcinus orca) off New Zealand to comprehend the interactions between energetics and the bioavailability of PCBs and DDT. Due to the inherent challenges associated with studying cetaceans in the wild, a multidisciplinary approach using toxicology, stable isotope analysis and ecological modeling is necessary to better understand the accumulation of contaminants in cetacean populations.


Bio: Meaghan McCormack is originally from Long Island, New York. She holds a B.A. in Biology from Adelphi University and an M.S. in Marine Affairs and Policy from the University of Miami. Her interest in marine mammal science stems from an appreciation of the evolutionary adaptations required of cetaceans, the ability of charismatic megafauna to generate interest in science, and the role cetaceans play as sentinel species. Meaghan started in the Ph.D. Program in Aquatic Resources at Texas State University in 2016.


Dissertation Proposal Defense


ALL IN THE FAMILY: THE AFFECTS OF URBANIZAITION AND CLIMATE CHANGE ON THE BEHAVIOR, SOCIALITY, AND POPULATION DYNAMICS OF A KIN-STRUCTURED PASSERINE, THE BLACK-CRESTED TITMOUSE (BAEOLOPHUS ATRICRISTATUS)


Rebekah J. Rylander
Major Advisor: Dr. Sarah Fritts (Department of Biology – Texas State University)

 

Committee Members: Dr. Butch Weckerly and Dr. Andrea Aspbury (Department of Biology - Texas State University), Dr. Thomas R. Simpson (Texas State University – Professor Emeritus), Dr. Michael Patten (Department of Biology - Oklahoma University)

Friday, November 16, 2018, 9:30 AM, Ingram Hall (IGRM) 3207


Climate change and habitat fragmentation through urbanization pose a threat to avian biodiversity on a global scale. Though many species are capable of co-existing in anthropogenic landscapes, there often are compromises in species’ survivorship, fecundity, and/or dispersal mechanisms. Avian species that are social can be even more affected by altered climate and urbanization due to additional challenges of maintaining familial bonds. A residential species of central Texas, the black-crested titmouse (Baeolophus atricristatus, BCTI), is a social songbird that forms kin-structured neighborhoods in rural, less-disturbed regions of its range. However, the titmouse also is regularly encountered in areas of high anthropogenic influence, but it is unknown how this altered landscape affects BCTI demographics, behaviors, and sociality. Thus, the focus of my dissertation research is three-fold: 1) assess the influence of urbanization on BCTI kin-structured neighborhood formation; 2) examine fitness costs and benefits associated with BCTI familial-living through resource sharing behaviors; and 3) compare BCTI population demographics and dynamics across varying levels of anthropogenic disturbance and seasonal weather patterns. I will perform this study in urban San Marcos, Texas and the Freeman Center of Texas State University. In both locations, I will capture, color-band, and monitor BCTI families that utilize nestboxes during the breeding season. Through focal observation and territory mapping, I will determine dispersal patterns, annual fecundity, survivorship, and kin-structure behaviors in locations with varying degrees of urbanization. With the use of passive integrated transponder (PIT) tag technology on the Freeman Center, I will examine the potential fitness benefits that BCTI receive through sharing behavior by residing next to relatives. Because this study will span seven years, I will assess the possible effects of weather patterns, in addition to urbanization, on the population dynamics of this species. Therefore, a thorough investigation of the BCTI could lead to better-focused conservation practices for socially-oriented species, especially in the face of inevitable habitat fragmentation and climate change.


Bio: Rebekah Rylander grew up in central Texas where she fell in love with avifauna during her bachelor’s degree from UT Austin. After a whirlwind of travel and exciting field experience, Rebekah settled into Texas State University where she earned her master’s degree studying social flocking dynamics of the black-crested titmouse. Because of the questions that surfaced after degree completion, Rebekah decided to continue working with titmice and their unique behaviors. During her limited spare time, Rebekah enjoys assisting undergraduates in research projects, performing banding station demos, and monitoring a local population of golden-cheeked warblers.


Dissertation Defense

 

AN INTEGRATIVE APPROACH TO THE ECOLOGY AND EVOLUTION OF ALTERNATIVE REPRODUCTIVE TACTICS IN MALE SAILFIN MOLLIES, POECILIA LATIPINNA


Diana Kim


Major Advisor: Dr. Caitlin Gabor

 

Dr. Chris Nice, Texas State University

Dr. Ryan Earley, University of Alabama, Tuscaloosa

Dr. Felix Breden, Simon Fraser University

 

Tuesday, November 13, 2018 - 2 pm, Ingram Hall, 03203


Understanding the sources of variation that make up complex phenotypes has been a long-standing goal of evolutionary biology. Sexually-selected polymorphisms such as those found in alternative reproductive tactics (ARTs) are an example of complex phenotypes that show extreme variation among multiple traits. Males often show phenotypic traits that vary in size, ornamentation, coloration, and behavior. For my dissertation, I used an integrative approach to investigate aspects of the social, hormonal and genetic effects that contribute to alternative reproductive tactics using male sailfin mollies, Poecilia latipinna, a live-bearing fish species. Complex phenotypes have both genetic and environmental sources of variation, and hormones often mediate the interaction between these two sources. Maternal effects and the presence of rival males are two such social environmental factors that can affect male phenotypes. First, I examined the effects of other rival males on male mate choice for conspecific females, and on the changes in circulating levels of the androgen 11-ketotestosterone (KT) and cortisol within a mate choice context. Although rival males did not affect male mate choice, these potential competitors did affect the KT release rates of focal males and females. Further, males released more KT with increasing size of the rival male. Then, I investigated how cortisol release rates varied in female sailfin mollies during gestation to identify the potential effects of maternal stress on son phenotype. I conducted an adrenocorticotropic hormone (ACTH)-challenge to determine the natural range of cortisol by gestating and non-gestating females and whether within and among individual variation (repeatability) contributed to female cortisol release rates. Gestational status did not correlate with cortisol but females showed high repeatability in cortisol release rates which suggests that variation in maternal stress may affect offspring and that cortisol release rates may be heritable. Lastly, I identified the genetic basis of male phenotypic variation using a genome-wide association study. Using a Bayesian sparse linear mixed model approach, I characterize the underlying genomic architecture of relevant morphological traits that define ARTs in male sailfin such as body size. Together, these chapters provide greater understanding of the genetic and physiological mechanisms for the variation in male phenotypes of sailfin mollies.


Bio: Diana was born in Pusan, South Korea but raised in Monticello, NY. Diana earned her B.A. degree in Biology from Wesleyan University in Middletown, CT and a M.S. degree from University of Wisconsin-Milwaukee


Dissertation Proposal Defense

 

Assessing population dynamics of threatened and endemic aquatic species using genetic and mark-recapture analyses


Alex Sotola


Major Advisor: Dr. Noland Martin

Committee Members:

Dr. Timothy Bonner, Texas State University

Dr. Chris Nice, Texas State University

Dr. Daniel Stich, SUNY Oneonta

Dr. Jess Jones, Virginia Tech

  

Wednesday November 14, 2018, 12PM, Freeman Aquatic Building 102

 


Anthropogenic influences on our ecosystems have increased in the last 100 years and will continue to do so. In the aquatic world, it is apparent how humans are influencing populations, whether it be by blocking migratory routes with dams, turning a lotic system into a more lentic system, or altering water quality or flows. As human influences continue to increase, our ability to assess and manage populations of conservation concern is increasing as well. Two powerful techniques that can be used to assess population dynamics and help manage threatened and endemic species are the use of genotyping-by-sequencing and mark-recapture methods. Not only can these techniques help with managing species of concern, but they can also help to better understand their biology (e.g., environmental influences, historical processes, or population dynamics). The three chapters of my dissertation proposal will provide valuable information about endemic species of conservation concern with regards to their population dynamics from a molecular and population level. My first chapter assesses hybridization dynamics between the endemic and threatened prairie chub (Macrhybopsis australis) and the widespread shoal chub (M. hyostoma) in the Red River basin of Texas. My second chapter is a biogeographical assessment of the Macrhybopsis species complex within Texas using molecular techniques. The complex consists of five species (potentially six), of which four (potentially five) are endemic to Texas or the basins surrounding Texas. My third and final chapter is a Pollock’s Closed Robust Design mark-capture study of two endemic freshwater mussels, which are also species of concern, the Texas pimpleback (Cyclonaias petrina) and smooth pimpleback (C. houstonensis). These three chapters will provide valuable information about the hybridization dynamics of fishes in the wild, historical biogeography of fishes within Texas, and population dynamics of freshwater mussels in Texas.


Bio: Alex was born and raised in upstate New York. He graduated from Plattsburgh State University in 2012 with a B.S. in Ecology. Subsequently worked for two years at the University of Vermont as a fisheries research technician. Completed his master’s degree in 2016 at Eastern Illinois University in Biological Sciences focusing on fisheries genetics. Started his PhD here in 2016 in Aquatic Resources.


Thesis Defense

Population structure and gene flow in the Louisiana Irises


Alex Zalmat
Major Advisor: Dr. Noland Martin

Committee Members: Dr. Chris Nice (Biology) and Dr. James Ott (Biology)

Tuesday, November 6, 2018, 2 PM,  IGRM 3203


Identifying the distribution of genetic variation and gene flow is fundamental to understanding the evolutionary history and dynamics of populations undergoing divergence. Natural selection and genetic drift shape the distribution of population structure and gene flow throughout the ranges of species and can drive the divergence of taxa. With the advent of next generation DNA sequencing techniques, it is now possible to explore population structure and gene flow at a genomic level throughout the range of such ecologically divergent taxa. The Louisiana Irises (Iris, series Hexagonae) comprise a group of three or more ecologically and reproductively divergent lineages that occasionally still produce hybrids in nature, giving us an opportunity to explore the process of speciation as it happens.  Here we sampled populations of Louisiana Iris spp. in an attempt to characterize population structure and gene flow throughout their respective ranges. We discovered evidence for gene flow in some parts of the range and tested several standing hypotheses of nominal taxonomy accepted by Louisiana Iris enthusiasts. We also quantified introgression in a newly discovered hybrid zone between Iris hexagona and I. brevicaulis using a Bayesian Genomic Cline analysis. We also tested the hypothesis that a purportedly hybrid species, I. nelsonii, indeed shows ancestry from two or more of the hypothesized parental species. We discovered that a relatively small proportion of the loci we sampled in the hybrid zone are experiencing extreme patterns of introgression in the studied hybrid zone. We found evidence that population structure appears to be more complex than previous taxonomic designations suggest. It was also discovered that I. nelsonii only appeared to share ancestry with only one of the purported parent species, I. fulva. This study provides a foundation for future exploration of evolutionary dynamics affecting these taxa.


Bio: Alex grew up in Dallas, TX and received his bachelor’s degree in biology from Texas State University in 2014. He joined the biology graduate program at Texas State in Fall of 2014 and now lives in San Marcos, TX. He enjoys hiking with his dog Morgan, rock climbing, and fly-fishing on the San Marcos River. He hopes to use his bioinformatics skills in his professional life post graduation.


Thesis Defense

Investigating the Nocturnal Nest Box use of the Black-crested Titmouse (Baeolophus astricristatus)


Christina Farrell


Major Advisor: Dr. M. Clay Green, Department of Biology, Texas State University

Committee Members: Dr. Thomas R. Simpson, and Dr. Andrea Aspbury, Department of Biology, Texas State University

 

Tuesday, November 6, 2018, 2:00 PM, Supple Norris Room


  Nest boxes are used during the breeding season by many cavity-nesting birds, however less is known about the use of nest boxes as sites for roosting during the winter non-breeding season.  The Black-crested Titmouse (Baeolophus atricristatus; hereafter BCTI) is a member of the family Paridae, which is a family containing birds known to utilize nest boxes during the winter seasons. However, the BCTI is a species with undocumented or unknown roosting behavior. For this study, possible factors influencing the propensity for winter roosting in the BCTI were examined. I conducted nocturnal surveys on nest boxes with the use of a wireless infrared cavity inspection camera across two winter field seasons. I analyzed the influence of nightly weather conditions and vegetation on winter roosting. For the weather variables affecting the probability of roosting, a decrease in temperature was found to increase BCTI roosting. Vegetation density surrounding nest boxes was also found to influence roosting with an increase in vegetation leading to an increase in roosting frequency. This study has shown nest boxes are of use to BCTI during the non-breeding season and has shed light on some of the factors influencing their winter roosting behavior. Future analyses should further explore the effect of wind conditions on roosting, as wind speeds were not found to influence roosting probability. The specifics of habitat and vegetation preference on roosting site selection should also be further assessed to determine how habitat species composition affects nocturnal winter roosting. 


 Bio: Christina obtained a B.S. in Geography from Texas State University in Fall 2013 and began her M.S. in Wildlife Ecology at Texas State in Spring 2016. She recently accepted a position as the Biodiversity Researcher and Collections Curator at the Selah, Bamberger Ranch Preserve in Blanco, Texas.      


Dissertation Defense

An analysis of the effects of photosynthetically active radiation and recreation induced turbidity in the San Marcos River on the vegetative growth of Texas wild rice (Zizania texana Hitchc.)


Michele L. Crawford-Reynolds


Major Advisor: Thomas B. Hardy, Department of Biology, Texas State University

 

Committee Members: Tina M. Cade, Department of Agriculture, Texas State University, Robert D. Doyle, Department of Biology, Baylor University, David E. Lemke, Department of Biology, Texas State University, Weston H. Nowlin, Department of Biology, Texas State University, Paula S. Williamson, Department of Biology, Texas State University

 

Tuesday, November 6, 2018, 8:30 AM, Freeman Aquatic Biology Building, Room 130


Texas wild rice (TWR) is an endangered perennial macrophyte known to occur only in the San Marcos River, Hays County, Texas. Availability of photosynthetically active radiation (PAR) is an important abiotic factor affecting a plant’s biomass. The San Marcos River is impacted on a seasonal, weekly and diel basis by contact water recreation. Recreational activities can cause increases in suspended sediment induced turbidity resulting in a decrease in water clarity and reduction in ambient PAR. Studies were conducted to test the effect of a reduction in PAR on the vegetative growth of TWR. Results of ex situ experiments involving a reduction in PAR through shade frames (0%, 10%, 20%, 40%, and 80% PAR reductions) found that with only 20% ambient PAR (80% PAR reduction), above ground biomass, below ground biomass, above/below ground biomass, total biomass, shoot number, root number, and total leaf surface area of TWR plants were significantly reduced in two of three experimental periods. The second study focused on periods of low and high contact recreational use, the suspended sediment induced turbidity response, and the impact on TWR biomass production. Results showed that differences in TWR biomass production existed along a longitudinal gradient in the river. The Eastern Spillway study site, which had very limited upstream recreational activity, was compared to downstream treatment sites located at Sewell Park, Bicentennial Park, and Ramon Lucio, which all had substantial upstream recreational activity. Greater growth was found in TWR plants at the upstream Eastern Spillway site. Differences in biomass production are likely the result of lower levels of suspended sediment in the water column at the Eastern Spillway site, allowing for higher levels of PAR. No difference in the amount of periphyton on the leaf surface of plants at the different study sites under either low or high contact recreational use was found. Therefore, periphyton does not account for observed differences in TWR growth. Findings from this study suggest that locations in the river receiving more than 20% ambient PAR provide optimum habitat for the reintroduction of TWR. Predicted model trends in percent PAR reduction at various depths in the river showed 20% ambient light could be reached at 60cm. Turbidity levels and depth are important factors to consider when selecting sites for reintroduction of TWR. The results of these studies inform future conservation and management efforts to restore TWR to once historical habitat and increase areal coverage in the San Marcos River.


Bio: Michele received a B.S. in Biology in 1991 and M.A. in Biology in 1993 from the University of Incarnate Word. She completed a M.Ed. degree in Education from Sul Ross University in 1998. Michele is currently a tenured Biology Professor at Southwest Texas Junior College.


Thesis Defense

STOMACH CONTENT ANALYSIS OF THE INVASIVE SMALL INDIAN MONGOOSE (HERPESTES AUROPUNCTATUS) FROM PUERTO RICO


Candice M. Rodriguez


Major Advisor:  Iván Castro-Arellano

 

Committee Members: Thomas R. Simpson and Christopher Serenari 

 

Monday Nov. 5, 2018, 2:00 pm, Norris Room  


  Since their introduction to Puerto Rico as a form of biological pest control in the late 1800’s, the small Indian mongoose (Herpestes auropunctatus) has been identified as a reservoir for several zoonotic diseases and has been suggested as a factor affecting native fauna. Mongoose are considered generalist predators that readily switch prey consumption depending on prey availability. Puerto Rico is home to a diverse fauna with multiple endemic species. There are 7 ecological zones in Puerto Rico that vary in rainfall, elevation, and vegetations thus creating heterogeneous environments that likely differ in prey abundance which presumably results in diverging prey use by mongooses in distinct ecological zones. Prior dietary analyses conducted on introduced mongoose in Puerto Rico have focused on individual ecological zones. For the present study I contrasted mongoose diets from the subtropical moist forest zone and subtropical dry forest zones.  Stomach content was separated and analyzed to determine aggregate percentages of prey remain compositions for 5 categories (Invertebrate, reptile, mammal, vegetation, and other). Of 51 mongoose stomachs analyzed (Dry, n=22, Moist, n=29) there was a difference in category compositions across all mongooses but there was no difference in compositions of prey remains between ecological sites. Invertebrates conformed the largest category of prey (Dry=13.7%, Wet=9.4%) used by mongooses at both ecological zones.  Despite their large ecological differences, these zones proximity to each other likely allows prey distributions to overlap across both zones. Future studies on prey abundance per ecological zone would provide insights into whether mongooses are selecting or using prey based on their availability.


 Bio: Candice was raised in San Antonio, Texas. She received her Bachelor of Science Degree in Biology with a minor in Chemistry from Texas State University in Fall of 2015 where she then stayed to continue her Master of Science in Wildlife Ecology. She plans to apply the College of Veterinary Medicine at Michigan State University in the Spring of 2019. 


Thesis Defense

Exploring Latino Parent Attitudes Toward Science, Involvement in Science, and Perceptions of Value and Comfort of Family Science Events


Izzy De Leon


Major Advisor: Dr. Julie F. Westerlund

Committee Members: Dr. Kristy Daniel and Dr. Ruben Garza 

November 5, 2018, 8:45am in Supple 257


  Diversity within teams and organizations guards against groupthink and overconfidence, and improves their ability to problem solve and make predictions. Even though efforts have been made to increase diversity within the Science, Technology, Engineering, and Mathematics (STEM) fields, marginalized groups are still largely underrepresented in the STEM workforce. This study focused on the Latino population gap in representation within the STEM fields. Most programs aimed at increasing Latino representation in science focus on directly encouraging students to pursue STEM careers. This study explored Latino parents’ attitudes toward science and what types of informal science activities parents engage in with their children. I organized 15 family science events in San Marcos, Texas, in which parents completed a pre- and post-event attitude toward science survey and an additional parental involvement survey to find out their attitudes towards science and what types of informal science activities they are involved in with their children. The activities and experiments performed during the family science events utilized common household items or items that were inexpensive. Twenty-two Latino parents participated in the study and 15 completed both the pre- and post-attitude toward science survey. The attitude toward science survey had 14 items and was scored using a Likert-type scale with a minimum and maximum score of 14 and 70 respectively. Latino parent’s pre- and post-event attitude toward science means were 60.1 and 62.2 respectively for attending at least one family science event. On the parental involvement survey, Latino parents identified 27 science activities that they have performed with their children, with 67% of those being discovery-based indoor activities and 59% being free activities.  In terms of parent participation, the majority of Latino parents (73%) preferred free activities. This study can help inform school districts, principals, teachers, and informal science education organizations on strategies for changing Latino parent’s’ attitudes toward science and increasing their involvement in their children’s science education.


 Bio: Izzy De Leon was born and raised in San Antonio, TX. He received a Bachelor’s of Music in Violin Performance from Texas State University as well as a Bachelor’s of Science in Biology in 2016. During his undergraduate tenure, he studied the violin with Dr. Lynn F Ledbetter and was part of Dr. Kristy L Daniel’s research lab. In Spring of 2017 he began his Master’s of Science in Biology at Texas State University where he joined the lab of Dr. Julie F. Westerlund. While working on his Master’s, Izzy has had the opportunity to work with the Mentoring Matters program and HSI STEM IMPACT program on giving support and professional development to students that are underrepresented in STEM. Izzy has also had the privilege of attending a week long professional development at NASA’s Johnson Space Center to improve his teaching in science. In his spare time, Izzy likes to read and re-watch The Office, sometimes at the same time. He also maintains his fiddle chops by playing with the Starlight Symphony Orchestra and performing throughout the Austin-San Antonio corridor. Izzy can be reached at izzydeleon@txstate.edu.


Thesis Defense

Mercury Concentrations in Fish from the Guadalupe River, Texas: Relationships with Body Length and Trophic Position


Taylor Gold Quiros
Major Advisor: Dr. Jessica Dutton

Committee Members: Dr. Tim Bonner (Biology), Dr. Weston Nowlin (Biology), Clint Robertson (Texas Parks and Wildlife Department - Inland Fisheries)

Monday November 5, 2018, 2 pm, FAB 130


  Mercury (Hg) is a nonessential trace element that is toxic to aquatic life at low concentrations. Mercury is known to bioaccumulate over time in freshwater fish and biomagnify up freshwater food webs, so top predatory fish have the highest Hg body burden. Within Texas, Hg studies in freshwater fish have primarily focused on the northern half of the state and south Texas is relatively understudied. This study investigated the concentration of Hg in muscle tissue from 41 species of trophically diverse fish (n = 1,772) in relation to body length and trophic position at five sites on the Guadalupe River (Flat Rock Lake, Canyon Lake, Lake Dunlap, Gonzales, and Victoria) using a direct mercury analyzer and stable isotope analysis (δ13C, δ15N). The majority of species showed a positive relationship between body length and Hg concentration (p < 0.05), indicating that Hg was bioaccumulating over time. Striped mullet was the only species that displayed an inverse relationship due to growth dilution. Mercury concentrations were highest in top predators including longnose gar, flathead catfish, and striped bass, and lowest in moderate and low trophic level species, including Mexican tetra, threadfin shad, and suckermouth catfish. Within the five sites examined, the average Hg concentration in each species was higher in reservoir sites than riverine sites. There was a positive relationship (p < 0.05) between δ15N and Hg concentration at all sites except Victoria, indicating Hg biomagnification between trophic levels. Five species (flathead catfish, channel catfish, white bass, striped bass, and longnose gar) had at least one individual that exceeded the Texas Department of State Health Services (TDSHS) human health criterion for Hg (0.7 µg/g wet weight), with at least one species at each site exceeding the guideline. Based on this data, the current Hg advisory for Canyon Lake needs to be reevaluated and the other 4 investigated sites may need to have Hg advisories issued.


Bio: Bio: Taylor is a native of Seguin, Texas and earned her B.S. in Biology and Environmental Science from Trinity University in San Antonio in 2016. She enjoys hiking with her dog, Lily, and genuinely believes that Jurassic Park should be taught in public schools. She plans to start a PhD in fall 2019.


Thesis Defense

ASSESSMENT OF THE SMALL INDIAN MONGOOSE (HERPESTES AUROPUNCTATUS) IN SUSTAINING CATTLE FEVER TICK POPULATIONS IN PUERTO RICO


Madison Torres


Major Advisor: Dr. Ivan Castro-Arellano

 

Committee Members: Dr. Sarah Fritts and Dr. Thomas R. Simpson

 

Monday, November 5, 2018, 9:00 am, Supple 153


The ectoparasite Rhiphicephalus (Boophilus) microplus, also referred as Cattle Fever Tick (CFT), serves as the primary vector for the protozoan pathogen Babesia which causes bovine babesiosis in livestock and other wildlife hosts. Current management practices in Puerto Rico have failed to control CFT prevalence resulting in major economic loss. One factor that has not been directly addressed is the high pervasiveness of invasive Small Indian Mongoose (Herpestes auropunctatus) in Puerto Rico and their potential to serve as an alternate Cattle Fever Tick host. For this study, radio-telemetry and ectoparasite sampling was conducted on mongooses at five farm sites in Puerto Rico to estimate habitat use and ectoparasite prevalence. I estimated the overlap of mongoose home ranges within cattle pastures and compared utilized versus available habitat types. Mongooses were found to nonrandomly select for grasslands and a portion of all mongoose home range estimates overlapped with corresponding farm sites. R. microplus was not found on sampled mongooses, suggesting the mongoose is not serving as a host for CFT populations in Puerto Rico. These results show continued research is needed to evaluate all potential CFT hosts to implement improved management practices. This study also provides insight on movement patterns and habitat use for a highly invasive species prevalent throughout many Caribbean islands.


Bio: Madison obtained a Bachelor of Science degree in Wildlife Biology from Texas State University in Spring 2013 and began her Masters in Wildlife Ecology at Texas State in Fall 2013. For the last year and a half, she worked for the United States Department of Agriculture Wildlife Services conducting wildlife management throughout New York City. She is currently a Wildlife Biologist for an environmental consulting firm based in Austin, TX.


Dissertation Defense


Influence of Bacterial Outer Membrane Vesicles on Struvite Crystal Growth


Ashley Summers


Major Advisor: Dr. Robert JC McLean

Committee Members: Dr. Manish Kumar  and Dr. Jeffery W Schertzer, Binghamton University

Friday, November 2, 10:00 am, Supple 257


   Urinary tract infections (UTIs) are a very serious health concern, affecting millions of people each year. They lead to almost 10 million doctor’s visits and hundreds of thousands of hospital admissions every year in the United States (Mittal 2009). One of the common causatives of UTIs is Pseudomonas aeruginosa, a gram negative, aerobic, rod-shaped bacterium (Balcht 1994). As a potential way to deliver virulence factors, P. aeruginosa secrete outer membrane vesicles (OMV), which are formed through direct interaction of Pseudomonas quinolone signal (pqs) with the lipopolysaccharide component of the outer membrane (Wessel 2013). Strains used in this research have mutations in these genes in the pathway that result in the inhibition of the formation of OMV. Commonly seen in bacterial urinary tract infections is the presence of struvite crystals. These crystals precipitate in alkaline urine, and eventually form larger stones. Alkaline urine is caused by the hydrolysis of urea to ammonia via the enzyme urease (Le Corre 2005). The purpose of this research is to study if the presence of outer membrane vesicles produced in P. aeruginosa induce struvite crystal formation. Various strains of P. aeruginosa, with and without OMV, were grown in BHI (blood heart infused agar) and suspended in artificial urine. Since P. aeruginosa lacks urease, the urease action was mimicked by titrating artificial urine with ammonium hydroxide, inducing struvite crystal formation. The presence and shape (crystal habit) of struvite crystals was confirmed via phase contrast microscopy. Transmission electron microscopy (TEM) was used to confirm the prescence of OMV. When crystals were measured using imaging flow cytometry, there was no significant difference in crystal numbers in intact and fragmented P. aeruginosa cells regardless of the presence or absence of OMV; although the number of crystals formed was elevated in controls lacking bacteria. This in vitro data suggests that P. aeruginosa, regardless of OMV production, does not enhance struvite formation in artificial urine.


Bio: Ashley was born in South Texas where she grew up working on a farm that focused on the production of corn and cotton. She received a Bachelor of Science in Microbiology from Texas State University with with a double minor in biochemistry and honors studies. Ashley aims to attend medical school to become a pediatric cardiologist. She also hopes to continue doing research and provide access to medical resources to areas that lack any basic healthcare infrastructure. She thanks her family for all their love and support.

 


Dissertation Proposal


ALL IN THE FAMILY: THE AFFECTS OF URBANIZAITION AND CLIMATE CHANGE ON THE BEHAVIOR, SOCIALITY, AND POPULATION DYNAMICS OF A KIN-STRUCTURED PASSERINE, THE BLACK-CRESTED TITMOUSE (BAEOLOPHUS ATRICRISTATUS)


Rebekah J. Rylander
Major Advisor: Dr. Sarah Fritts (Department of Biology – Texas State University)

 

Committee Members: Dr. Butch Weckerly and Dr. Andrea Aspbury (Department of Biology - Texas State University), Dr. Thomas R. Simpson (Texas State University – Professor Emeritus), Dr. Michael Patten (Department of Biology - Oklahoma University)     

 

Friday, November 2, 2018, 9 AM, Supple 153

 


Climate change and habitat fragmentation through urbanization pose a threat to avian biodiversity on a global scale. Though many species are capable of co-existing in anthropogenic landscapes, there often are compromises in species’ survivorship, fecundity, and/or dispersal mechanisms. Avian species that are social can be even more affected by altered climate and urbanization due to additional challenges of maintaining familial bonds. A residential species of central Texas, the black-crested titmouse (Baeolophus atricristatus, BCTI), is a social songbird that forms kin-structured neighborhoods in rural, less-disturbed regions of its range. However, the titmouse also is regularly encountered in areas of high anthropogenic influence, but it is unknown how this altered landscape affects BCTI demographics, behaviors, and sociality. Thus, the focus of my dissertation research is three-fold: 1) assess the influence of urbanization on BCTI kin-structured neighborhood formation; 2) examine fitness costs and benefits associated with BCTI familial-living through resource sharing behaviors; and 3) compare BCTI population demographics and dynamics across varying levels of anthropogenic disturbance and seasonal weather patterns. I will perform this study in urban San Marcos, Texas and the Freeman Center of Texas State University. In both locations, I will capture, color-band, and monitor BCTI families that utilize nestboxes during the breeding season. Through focal observation and territory mapping, I will determine dispersal patterns, annual fecundity, survivorship, and kin-structure behaviors in locations with varying degrees of urbanization. With the use of passive integrated transponder (PIT) tag technology on the Freeman Center, I will examine the potential fitness benefits that BCTI receive through sharing behavior by residing next to relatives. Because this study will span seven years, I will assess the possible effects of weather patterns, in addition to urbanization, on the population dynamics of this species. Therefore, a thorough investigation of the BCTI could lead to better-focused conservation practices for socially-oriented species, especially in the face of inevitable habitat fragmentation and climate change.


Bio: Rebekah Rylander grew up in central Texas where she fell in love with avifauna during her bachelor’s degree from the UT Austin. After a whirlwind of travel and exciting field experience, Rebekah settled into Texas State University where she earned her master’s degree studying social flocking dynamics of the black-crested titmouse. Because of the questions that surfaced after degree completion, Rebekah decided to continue working with titmice and their unique behaviors. During her limited spare time, Rebekah enjoys assisting undergraduates in research projects, performing banding station demos, and monitoring a local population of golden-cheeked warblers.   


Thesis Defense

INITIAL RESPONSES OF AQUATIC BENTHIC MACROINVERTEBRATE COMMUNITIES TO LARGE FLOW PULSES IN THE GUADALUPE, SAN ANTONIO AND BRAZOS RIVER BASINS OF TEXAS


Jeremy Maikoetter


Major Advisor: Dr. Timothy Bonner

 

Committee Members: Dr. Caitlin Gabor (Biology), Dr. Archis Grubh (TPWD)

 

Thursday, November 1, 2018, 3:30 PM, FAB 130


Riverine benthic macroinvertebrates (BMI) communities are regulated, in part, by the dynamic character of the river’s flow regime. Purpose of this study was to assess the influence of a flow regime component (i.e., large flow pulse) on BMI riffle communities. Predictions were that BMI richness and density would decrease with large flow pulses, ranging between 1 in 2 year events (340 m3/s) to 1 in 5 year events (331 to 886 m3/s), but that density reductions would differ among taxa categorized as swiftwater, moderate, and slackwater forms. BMI communities were monitored at 11 sites located in three river basins and distributed among upper and lower reaches of major rivers and tributary streams. A total of 93,400 aquatic macroinvertebrates were identified to family and used to estimate BMI richness and BMI density among 102 riffles (61 riffles pre-flood and 41 riffles post-flood) between 2014 and 2017. Physical and chemical aspects of riffle habitats were similar between pre-flood and post-flood, except that post-flood riffles had less sand and gravel than pre-flood. BMI communities were similar among river basins and were segregated along environmental gradients related to physical and chemical (16%), season (6%), flood (2%) effects. Overall BMI richness decreased between pre-flood and post-flood at two sites. Changes in density were not detected at any of the 11 sites. Densities of swift and moderate BMI taxa increased at two sites; changes in slack BMI density were not detected at any sites. My initial predictions were largely unsupported, but continued monitoring of these communities will add to the current knowledge of flow pulse effects on BMI. Resistance and resiliency of the BMI communities were attributed to several factors and have implications to state-wide environmental flow standards and future water quantity biomonitoring.


Bio: Jeremy lives in New Braunfels, Texas with his wife Michelle and son Collin. He returned to Texas State University to complete his B.S. in Aquatic Biology in 2015 with a minor in Chemistry while assisting in the Bonner Aquatic Ecology Lab prior to starting the M.S. Aquatic Resources program in 2016. Throughout his time at Texas State University, he has studied several aspects of Aquatic Ecology, including fishes, aquatic insects, and freshwater mussels. Jeremy is currently a biologist for Zara Environmental and upon completion of his M.S. degree plans on continuing to study and monitor rare and imperiled aquatic and terrestrial species in Texas.


Thesis Defense

Classification of Small-Mammal Metacommunity Structures Along Elevational Gradients With Connections to Metacommunity Networks

Emily M. Javan

Major Advisor: Ivan Castro-Arellano

Committee Members: Ivan Castro-Arellano, Joseph Veech, Daniela Ferrero, Michael Willig Friday, Nov. 2, 2018, 1:00 pm, Supple 257

 

Small-mammals host a wide variety of zoonotic pathogens and thus their ecological patterns are intricately tied to the emergence of infectious diseases. They also serve an important role in ecosystem function by being prey and sources of seed dispersal. To assess the interaction structure, or metacommunity structure, of small- mammal assemblages, presence-absence surveys along elevational gradients were collected from the literature at both local and regional scales. In total, fifty-nine sources were used to create 337 species incidence matrices based on 104 study sites. Each incidence matrix was organized by six relatedness groupings: genus, family, suborder, order, superorder, and multiple superorders. Metacommunity structures changed due to the choice of relatedness grouping, but was independent of the size of the input matrix. Random metacommunity structures were rare and often reflected disconnected metacommunity networks. Metacommunity networks treat species as nodes with connecting edges weighted by species co-occurrence at elevational bands. Nestedness metrics did not depend on maximum elevation, average annual mean temperature, average annual precipitation, or the number of species clusters as determined by the Louvain method and Spinglass algorithm. Relativized nestedness did increase as the novel nestedness metric, species deletion ratio, increased at both local and regional scales. Further analyses should explore the use of geographical information system software and clustering algorithms that allow species to be in multiple clusters. The habitat preference and temporal niche of each species should also be assessed to determine to what extent co-occurrence implies species interactions and potential transmission of infectious pathogens.

 

Bio: Emily received her Bachelor of Science degree in Applied Mathematics with a minor in Ecology, Evolution, and Biodiversity from UC Davis in Spring 2014. She began her Masters in Population and Conservation Biology at Texas State University in the Fall of 2016. She plans to start at PhD in Mathematical Epidemiology with an emphasis on network science in Fall 2019.


Dissertation Defense

The Genomics of Speciation


Katherine Bell

Major Advisor: Dr. Chris Nice

Committee Members: Dr. Noland Martin, Texas State University

Dr. Jim Ott, Texas State University

Dr. Jim Fordyce, University of Tennessee

Dr. Darrin C. Hulsey, University of Konstanz

 

Monday October 29, 2018, 9am, Supple Science Building, Room 153


Speciation, the process by which reproductive isolation evolves between diverging lineages, is pivotal to our understanding of evolution. Across multiple wild populations I explored the genetic architecture of reproductive isolation and adaptive traits, the interaction between gene flow and genetic architecture of traits and their impact on the process of speciation, and finally I assessed the repeatability of genetic differentiation and absolute diversity across the genome, across multiple species pair comparisons. My dissertation includes investigations of hybridization between pitcher plants (Sarracenia sp.), a repeated trophic polymorphism within the Cuatro Ciénagas cichlid fish (Herichthys minckleyi), and a species complex of blue butterflies (Lycaeides sp.) that have a complicated evolutionary history that includes repeated, independent evolution of hybrid species. I generated genome-wide population genetic data to quantify patterns of genomic differentiation in all of these case studies. I used a combination of analyses to dissect the relationships between trait architecture, adaptation, and reproductive isolation. Bayesian clustering was used to describe patterns of variation and identify areas of admixture. Bayesian Sparse Linear Mixed Models (BSLMM) were used to map the genetic architecture of a variety of traits and I compared estimates of introgression for genomic regions that contribute to trait variation to understand if these traits are associated with fitness in admixed individuals. Bayesian Genomic Cline models were used to identify patterns of introgression and excess ancestry in admixed individuals. Patterns of differentiation measured along chromosomes was used to assess the repeatability of differentiation and potential adaptation. I found remarkable variation in trait architecture, ranging from very simple to highly complex. Many genomic regions were associated both with trait variation and patterns of strong selection, though this was not universal. Repeatable patterns were detected in some regions of the genome which suggests that evolution can be predictable, yet there are also instances of unrepeated differentiation suggesting a role for historical contingency. Overall, my results contribute to our understanding of the process of speciation and highlight the power of genome-wide data to resolve important questions in evolution.


Bio: Kate was raised in Dorset, in southern England. In 2009 she obtained a Bachelor of Science degree with Honors in Zoology from Queen Mary, University of London. In 2012 she completed a Master of Science in Population and Conservation Biology from Texas State University. She stayed at Texas State and begun a Ph.D. in 2012 in Aquatic Resources.

 

 


 

Thesis Defense

The use of 23S ribotyping to detect harmful and nuisance phytoplankton in a large, subtropical reservoir during an extended drought period


Tatiana Gámez
Major Advisor:  Dr. Alan Groeger

Committee Members:  Dr. Schonna Manning (University of Texas), Dr. Vicente Lopes (Texas State University)

Friday, October 19, 2018, 9:00 AM, Freeman Aquatic Building 102


Inland subtropical water bodies are highly susceptible to freshwater harmful algal blooms (HABs). Still, there remains a lack of studies on this subject and the conditions encouraging blooms in this climate. Central Texas, USA, went through an extended drought from 2011-2015 – a phenomenon common in the subtropics. Lake Buchanan, a large inland reservoir, experienced rapid shifts in the phytoplankton community during this period as the lake transitioned to more eutrophic conditions, and serves as an excellent model for subtropical lakes due to its location and size. Samples were taken bimonthly and included measuring water quality parameters, nutrients and phytoplankton, along with the identification of living and preserved phytoplankton to assess the impacts of the transition. The phytoplankton community was evaluated by cell counts and DNA barcoding using 23S ribotyping to verify the presence and abundance of different strains. Abiotic and biotic factors were evaluated to determine which variables contributed to the formation of HABs. DNA sequencing analysis confirmed the presence of known bloom-forming cyanobacteria. Overall, this study shows that the saxitoxin-producers Planktothrix, Aphanizomenon, and Cylindrospermopsis thrived in drought conditions (p = < 0.001) whereas Limnothrix and Pseudanabaena did not. The diatoms Fragilaria and Lindavia increased in terms of community dominance after the end of the drought. Following the drought period, Aphanizomenon ovalisporum, Phormidium tenue, and Planktothrix sp. were present along with additional potentially harmful yet rarely studied species. These results suggest that drought-induced eutrophication lead to the dominance of harmful cyanobacteria in Lake Buchanan. Thus, subtropical reservoirs should be monitored closely during extended drought periods, as the risks associated with eutrophication and HABs are predicted to be higher.


Bio: Tatiana earned her Bachelor of Science degree from the University of North Texas in Spring 2015 with an Ecology major and Chemistry minor. She joined the Aquatic Biology program at Texas State in Fall 2016.  


Dissertation Proposal Defense

Descriptions, classifications, and explanations of processes and patterns structuring and maintaining inland fish communities


Cody A. Craig


Major Advisor: Timothy H. Bonner, Department of Biology, Texas State University

Committee Members:  

Emmanuel Frimpong, Department of Fish and Wildlife Conservation, Virginia Tech

Keith B. Gido, Division of Biology, Kansas State University

Noland H. Martin, Department of Biology, Texas State University

Chris C. Nice, Department of Biology, Texas State University

Tuesday, October 2, 2018, 2:00 PM, Freeman Aquatic Biology Building, Room 102


Factors influencing fish community structure are numerous, complex, and interdependent. Structuring mechanisms of aquatic communities fall within four broad classes (i.e., zoogeography and deep-evolution, local abiotic and biotic phenomena, autecology of individual species, and biotic interactions among fishes) and explain why fishes are found in local and regional communities. The common theme among chapters is identification of patterns that aid in understanding contributions of the four broad classes in regulating fish community structure. A unique contribution of my work is the application of theoretical community ecology framework across multiple scales, from individuals to ecoregions, using descriptive and manipulative field and laboratory experiments. Chapter 1 provides drainage basin keys for Texas inland fishes, which provides accurate identification of study organisms. Chapter 2 quantifies habitat associations and guilds of western gulf slope fishes (S = 146) to describe autecology and ecological niches within fish communities. Remaining chapters focus on identification of mechanisms that maintain fish community structure, including water quantity within riverine environments (Chapter 3-- Responses of the Brazos, Guadalupe, and San Antonio rivers to environmental flows), water quantity and water quality within spring complexes (Chapter 4--Nueces historical and current fish community,  Chapter 5--San Antonio historical and current fish community), and biotic factors (Chapter 6--Temperature-mediated feeding between spring-associated and riverine-associated congeners, with implications for community segregation).


Bio: Cody is from Longview, Texas. He graduated with his B.S.-Wildlife and Fisheries Management from Texas Tech University in 2012. Cody completed his M.S.-Aquatic Resources in December 2014 studying the relationship between spring flow magnitude and fish communities. He began as a PhD student in 2016 and plans to complete his PhD in 2020.


Thesis Defense

Detectability affects the performance of survey methods - a comparison of sampling methods of freshwater mussels in Central Texas


Brittney Sanchez
Major Advisor: Dr. Astrid Schwalb

Committee Members: Dr. Weston Nowlin (Biology), Dr. David Rodriguez (Biology)

Friday, August 24, 2018, 1:30 PM, Freeman Aquatic Biology 130


Designing effective surveys for freshwater mussels (Unionidae)is a challenge, because they are spatially clustered and often found in low densities. The objective of this study was to examine how the effectiveness of three different survey methods (timed searches, transect method, and adaptive cluster method) varied between different habitats at six sites in the San Saba, Guadalupe, and San Antonio Rivers in Central Texas.  Species richness, the total number of mussels per search effort, species composition and size distribution obtained with different survey methods were compared between sites. Timed searches were generally the most effective method in detecting species especially when densities were low (≤ 0.2 individuals per m2) or mussels were highly clustered. The adaptive cluster method, however, was as effective as timed searches in detecting species when densities were moderate or higher (>2 ind. per m2) and detected more species than timed searches at a site at which habitat conditions hindered searches. The performance of adaptive cluster in respect to number of mussels found per unit search effort seemed to be enhanced by sandy substrate facilitating detection of mussels, whereas timed searches were less effective at sites at which habitat conditions hindered the detectability of mussels. Differences in detectability of mussels was not only associated with habitat conditions, but also with the size of mussels, their behavior and morphology. Timed searches detected a larger proportion of larger mussels that tended to be less burrowed and that had shells with more sculpturing compared to quantitative methods. In addition, surveyors with more search experience detected a larger number of mussels. Our results suggest that to design effective surveys variation in detectability of mussels must be considered which depends on local habitat conditions, experience of surveyor, behavior, size and morphology of mussels.


Bio: Brittney is from Uvalde, Texas. She moved here in August of 2010 to begin her undergraduate degree in Biology. In 2016 she began the graduate program and has been juggling a variety of responsibilities such as teaching Biology as a high school teacher in San Antonio, teaching as a graduate instructional assistant in San Marcos, and finishing up her research in the Schwalb lab. She is passionate about working hard, science, health, and helping others. She is thankful and grateful for the experience and research she has conducted in the Schwalb lab. She hopes to continue research in her future endeavors.


Thesis Defense

Interspecific Spacing between Harvester Ant (Pogonomyrmex barbatus) and Red Imported Fire Ant (Solenopsis invicta) Colonies along the Invasion Gradient in Texas


Skyler Flaska


Major Advisor: Dr. Joseph Veech

 

Committee Members: Dr. Sarah Fritts (Biology), Dr. Todd Swannack (USACE and Dept. of Biology)

 

Friday, August 3, 2018, 1:00 PM, Supple 153

 


Invasive species can be devastating to ecosystems and their impacts on native species are innumerable. The red imported fire ant (Solenopsis invicta) invasion is a threat to many native species and is one hypothesized explanation for the observed decrease in the red harvester ant (Pogonomyrmex barbatus). Understanding how S. invicta affects harvester ants is important given harvester ants’ beneficial role in ecosystems and as a prey base for certain species. In this study I performed a “space for time substitution” to investigate if the ecological interactions between these two species has changed over time. Using data on the interspecific spacing between P. barbatus and S. invicta colonies and density of S. invicta colonies in the vicinity of P. barbatus colonies (compared to neighboring random points), the goal of my study was to quantitatively characterize these interactions and test if they differ across the invasion gradient of S. invicta in Texas. I predicted that interspecific spacing might increase with time since first contact if P. barbatus colonies have developed an avoidance response. I obtained data for 125 P. barbatus colonies at 24 study sites. I did not find a significant difference in the spatial interaction between the two species along the invasion gradient. However, my study provided some evidence for the possibility of coexistence without an adaptive avoidance response by P. barbatus. The size of P. barbatus colonies becomes significantly larger as the distance to nearest fire ant mound decreases but colony size becomes smaller as density of fire ant mounds increases. This result might represent a relatively intricate interaction worthy of future research. Overall my results indicate that S. invicta may not negatively impact P. barbatus to the extent commonly thought, although S. invicta likely remains a threat to other native species.


Bio: Skyler is from Mineral Wells, Texas, and moved to San Marcos in the fall of 2016 when he joined the Wildlife Ecology graduate program. He graduated cum laude from Tarleton State University with his Bachelor of Science degree in Biology with an emphasis on Environmental Science and a minor in Chemistry in May 2015. Upon successful completion of his master’s Skyler will be attending the University of Louisiana in Lafayette to pursue a Ph.D. in Biology focusing on assimilation wetland ecology.


Thesis Defense

EXPERIMENTAL TESTS OF THE EFFECTS OF EXOTIC HETEROPHYID METACERCARIAE ON THE SWIMMING ENDURANCE OF SMALL FISH HOSTS


Kelby Clements


Major Advisor: Dr. David Huffman

 

Committee Members: Dr. Timothy Bonner and Dr. Clay Green

 

Thursday, July 5, 2018, 2:00 PM, FAB 130

 An exotic snail from Asia (Melanoides tuberculata) has been introduced into many Texas springs and has become of great ecological concern due to harmful trematode parasites it harbors. The larvae of two of these parasites (Centrocestus formosanus and Haplorchis pumilio) infect many native fishes, some of which are listed species, and have become the most common trematodes in habitats they infest. Many studies have explored the pathology of C. formosanus in different host species, but after 20+ years and hundreds of thousands of dollars, conservation workers are still unable to quantify what effects the parasite is having on the relative fitness of affected fish, meanwhile, the effects of H. pumilio have been virtually ignored. Almost any task most fish must perform in order to compete for food, mates, spawning sites, or to escape from predators, relies on the ability of the fish to swim either at its maximum speed or at lower speeds for sustained time. Anything that negatively affects the swimming performance of such fish will reduce the individual’s ability to thrive. We have developed a device to test the swimming performance of small fish to measure the reduction in performance caused by varying levels of infection with either Centrocestus formosanus or Haplorchis pumilio. Our findings indicate that high levels of infection with Haplorchis pumilio can cause mortality while non-lethal exposure has profound effects on the swimming performance of Cyprinella venusta and the threatened Dionda diaboli. Indeed, we can now specify the percent reduction in swimming performance that can be attributed to infection with H. pumilio. Interestingly, however, C. formosanus had virtually no measurable effects on swimming performance. We conclude that, except for the fountain darter, which is dramatically affected by C. formosanus, more research should be focused on studying H. pumilio as a greater threat to native fishes.


Bio: Kelby is from Gustine, Texas, and moved to San Marcos in 2016 when he joined the Biology graduate program. He earned his Bachelor of Science degree in Wildlife Management from Texas State University in 2012. Kelby enjoys backpacking trips, rock climbing, and winter sports and has plans to move to New Zealand to pursue a career in wildlife conservation.


 

Thesis Defense

Modeling Detection and Density Using Distance Sampling for Three Priority Grassland Bird Species in Texas – Northern Bobwhite (Colinus virginianus), Eastern Meadowlark (Sturnella magna), and Painted Bunting (Passerina ciris)


Name: Anna Matthews

 


Major Advisor: Dr. M. Clay Green

 

Committee Members: Dr. Floyd Weckerly and Dr. Jennifer Jensen

 

Thursday, July 5, 2018, 10:00 AM, Supple 153


Within Texas, three priority grassland species that have experience declines due to loss of native grasslands are the Northern Bobwhite (Colinus virginianus), Eastern Meadowlark (Sturnella magna), and Painted Bunting (Passerina ciris). This 5-year study identified covariates that influence detection, availability, and density for these three species using data collected from 986 surveys across 11 Texas counties. Points were visited once per year from 2013 to 2017 in May and June, and 5-minute point counts were performed using distance sampling protocols. Models were fit using gdistsamp from the package “unmarked” in R. Covariates that influenced detection for Northern Bobwhite were observer, ambient noise, time of day, and Julian date. Detection was higher later in the season, earlier in the morning, and at lower ambient noise levels. Julian date and observer influenced Eastern Meadowlark detection, with detection declining later in the season. Painted Bunting detection was influenced by ambient noise and observer, although the effect of ambient noise appears to be negligible. The proportion of individuals available for detection was influenced by year, showing trends that are likely influenced by precipitation from the preceding year. However, despite this, availability for all species was not influenced by the Palmer Drought Severity Index. Vegetative cover was selected in the top density model for all three species. Native grasslands positively influenced density of Northern Bobwhite and Eastern Meadowlarks, shrubland positively influenced bobwhite and Painted Bunting, and cropland positively influenced bobwhite. Overall, there was high variability in the effect of vegetative cover on density across the three species, indicating that management for one species may ignore vegetative cover needs of other grassland species. Finally, for all species, monitoring should emphasize observer training and attempt to survey only under low ambient noise conditions.


Bio: Anna was born and raised in Dallas, Texas. She left Texas for freezing weather to receive a Bachelor of Science in Fisheries and Wildlife from the University of Minnesota. While there, she discovered a passion for birds, grassland conservation, and education, and she has been fortunate to be able to continue to expand her knowledge and experience in these fields as a graduate student at Texas State University.


Thesis Defense

DETERMINING THE IMPACT OF A CORRELATED SCIENCE AND MATHEMATICS PROFESSIONAL DEVELOPMENT MODEL ON TEACHER LEADERSHIP


Ruby Hernandez


Major Advisor: Dr. Sandra West

 

Committee Members: Dr. Julie Westerlund, Dr. Emily Summers, and Dr. Sandra Browning

 

 

July 5, 2018, 7:30 AM, Norris Room Supple 376


The mathematics and science national standards advocate for educational reform by implementing research-based strategies that includes recognizing the teacher’s critical role in effective instruction. A school’s success can be attributed to recognizing and fostering teacher leadership development. Teachers often feel empowered and become advocates for integration on their campus when they understand how to relate mathematics and science grade-level content in a meaningful way. The purpose of the Correlated Science and Math professional development model used in the Mix It Up project was to better enable science and mathematics integration by classroom teachers. My study aimed to determine the impact of the Mix It Up project on teacher leadership growth in a 2-year cohort (n=23). I investigated teacher leadership using a mixed-methods approach which allowed me to understand if and how teacher leadership growth is occurring. I selected a multiple case study (n=4) to gather enriched details of the process of teachers in MIX progressing into teacher leadership by attaining stage 3, the highest level of leadership, using the NCSM PRIME Leadership Framework. Overall, MIX teachers’ reported they possessed teacher leadership characteristics while 91% reported taking on leadership roles outside their classrooms and stage 3 leaders in my case study attributed their leadership growth to their participation in the MIX PD program. Participants’ reported they were not only implementing and impacting their own students, but were ultimately advocating for science and mathematics integration and the use of general best practices at the district and even state level


Bio: Ruby A. Hernandez is a former high school Biology teacher and plans to return to teaching science in middle or high school to broaden her experience in teacher leader progression. She was born in San Antonio, Texas where she earned her Bachelor of Arts degree in Biology with a minor in secondary education at the University of the Incarnate Word in 2014. She joined the Biology graduate program in Fall 2016.


Thesis Defense

Variation in temperature tolerance of two invasive snails in Texas


Linus Ray Delices


Major Advisor: Astrid Schwalb, Department of Biology, Texas State University

 

Committee Members: Weston Nowlin, Department of Biology, Texas State University

Benjamin Schwartz, Department of Biology, Texas State University

 

Tuesday July 3rd, 2018, 10:00 AM, FAB 130


Invasive species are a major concern for aquatic ecosystems and tropical freshwater snails (Thiaridae) can be very successful invaders. Melanoides tuberculata and Tarebia granifera are two invasive snails in Central Texas that serve as intermediate hosts for several Asiatic trematode parasites of fishes, birds, and other organisms. A better understanding of their temperature tolerances is needed to better predict their spread in Texas and to inform management strategies. Therefore, the goal of my study was to determine the critical thermal minima of these species and to compare temperature tolerances between species, river segments, and different local morphotypes. Survival of snails were monitored in environmental tanks in which temperature was decreased by 0.1°C per hour from 23°C to 10°C. In addition, survival was monitored over time in environmental tanks in which temperature was held constant at 17°C, 15°C, 11°C and 10°C after acclimatization. M. tuberculata showed slightly higher survival at colder temperatures compared to T. granifera. There was no significant difference between local morphotypes of M. tuberculata found in Central Texas, and there were some differences in temperature tolerances of snails between river segments i.e. the upper and lower San Marcos and Guadalupe Rivers. My results show that M. tuberculata can tolerate colder temperatures down to 11°C for a few weeks, which will facilitate their dispersal in rivers of Central Texas farther away from thermally stable spring influenced reaches. Further research is need to examine differences in thermal preferenda and temperature tolerances of snails between rivers.


Bio: Linus grew up in the small town of Viuex-Fort, Saint. Lucia-West Indies. He earned his Bachelor of Science in Biology with a second major in Psychology at Grambling State University. He joined the Biology graduate program in Spring 2015. He is passionate about science and he willingly shared his gifts, talents, keen-eye, great personality and knowledge with others.


Thesis Defense

Impact of Environmental Contaminants on the Threeridge mussel (Amblema plicata) in the Guadalupe River Basin, Texas


Name: Stacey Britton


Major Advisors: Dr. Jessica Dutton and Dr. Astrid Schwalb

 

Committee Members: Clint Robertson (Texas Parks and Wildlife Department- Inland Fisheries)

 

 

July 2, 2018, 10:00 AM, Freeman Aquatic Biology 130


Aquatic pollution has contributed to the significant decline in unionid mussels in North America; however, toxicological studies on Texas unionids are limited. In this study, adult Threeridge (Amblema plicata) mussels were collected from 8 sites within the Guadalupe River basin and the concentration of 8 essential (Co, Cu, Fe, Mn, Mo, Ni, Se, Zn) and 8 nonessential (Ag, As, Cd, Cr, Hg, Pb, Sn, V) trace elements were determined in gill and foot tissues. Additionally, water samples from each site were analyzed for nutrient concentrations. Biomarker analysis (lipid peroxidation, total antioxidant capacity against peroxyl radicals, and protein content) of gill tissue was used to quantify the physiological response of mussels to environmental stressors. Contrary to my expectations, trace element uptake, nutrient concentrations, and physiological stress responses were not necessarily higher at downstream sites. Hg and As concentration in gill tissue were observed to be highest in mussels at the uppermost sites on the San Marcos River and Guadalupe River, respectively. Trace element concentrations in gill tissue did not correlate with general physiological stress biomarkers in mussels; however, higher total nitrogen and total phosphorous concentrations at upstream sites correlated with a) higher lipid peroxidation and lower antioxidant capacity against free radicals, indicating greater oxidative stress, and b) lower protein concentration indicating reduced overall health of adult mussels. Future studies need to investigate the impact of these contaminants on glochidia and juvenile mussels, since early life stages are more sensitive to exposure.


Bio: Stacey has spent the last decade living between Austin and Seattle while pursuing an education in science and raising two bright young girls. Stacey earned her B.S. in Biology with a minor in Chemistry at Texas State University in 2016. She is passionate about science outreach and youth mentorship and hopes to encourage the next generation of environmentalists and ecologists to find their voice.


Thesis Defense

AN INVESTIGATION OF PRESERVICE TEACHERS’ ENGAGEMENT AND PERCEPTIONS OF SCIENCE LEARNING IN OUTDOOR LEARNING ENVIRONMENTS


Sara Salisbury
Major Advisor: Dr. Kristy Daniel 

Committee Members: Dr. Michelle Forsythe and Dr. Julie Westerlund

 

Friday, June 1, 2018, 1:30 PM, SUPP 257


Science education programs that use both formal and informal instruction provide students with more engaging experiences than when only using traditional instruction. However, educators often do not know of, or are uncomfortable with using informal resources. Thus, understanding how educators view and experience science learning in informal environments is necessary for increasing the likelihood that these educators will integrate informal science resources into their curricula. The purpose of this study is to investigate relationships amongst preservice teacher engagement during informal, outdoor learning activities, and perceptions about using informal resources during their future teaching career. During this study, preservice teachers (n=5) took part in a one-day, nature-based fieldtrip as part of a General Science education course. During this fieldtrip, they learned science content and how to teach science in a fieldtrip setting. Using a four-dimensional framework of engagement (i.e., behavioral, cognitive, affective, agentic), I analyzed video, eye-tracking, and interview data to identify moments of engagement, preservice teachers’ perceptions of the fieldtrip, and their integration ideas for using outdoor learning environments in their future teaching career. Overall, participants’ actions indicated their engagement across all four dimensions. Participants thought highly of using outdoor learning environments as potential teaching tools, and could identify some way they could integrate them into future teaching practices. No clear relationship existed between observable engagement actions and preservice teachers’ future integration ideas; However, participants’ overall past experiences with informal learning environments (including the General Science fieldtrip) appeared to largely influence their perceptions and integration ideas. Participants who had no prior teaching experiences drew primarily on their experiences as a student, whereas participants with informal and formal teaching experiences drew upon their experiences as a teacher more than their experiences as a student. Observable engagement actions and interview responses also suggested some participants underwent personally meaningful learning experiences.


Bio: Sara is from New Jersey, and moved to San Marcos in 2016 when she joined the Biology graduate program. She earned her Bachelor’s of Science degree in Environmental Science with a minor in studio art from Allegheny College in 2012. Sara is an avid rock climber, and hopes to someday become a Director of Researcher and Education at an outdoor education institution.


Master’s Thesis Defense

 Bacterial community structure in soils of the oldest agronomic experiment fields in the United States, the Morrow Plots, and of the original tallgrass prairie  


Abirama Sundari Ganesan

 

Major Advisor: Dr. Dittmar Hahn

Committee Members: Dr. Robert McLean and Dr. David Rodriguez

 

Wednesday, May 16, 2018, 10:00 am, Supple 257


New molecular techniques that focus on high throughput DNA sequencing techniques such as 454 pyrosequencing and the MiSeq sequencing platforms revolutionized the field of microbial diversity studies. These techniques are widely used in projects such as the Earth Microbiome Project (EMP), a collective attempt to establish microbial fingerprints in different environments of the planet. Additional applications include studies on long-term effects of crop rotation and different fertilization regimen on bacterial community structure. We tried to build on these studies and assess microbial community structure in the Morrow Plots, the oldest agronomic experimental fields in the United States, and adjacent tallgrass prairie with emphasis on members of the genus Frankia. The Morrow Plots were designed in 1876 on tallgrass prairie soils to evaluate the effects of different cropping systems and soil treatments on crop, and include the oldest continuous corn plots in the world. Illumina-based 16S rRNA V3 amplicon sequencing retrieved total of 26.47 M effective sequences obtained from 44 samples, i.e. 12 soils with different vegetation and fertilization, and 3 to 6 replicates per soil, with 313,695 to 906,328 reads per sample. At a sequencing depth of 300,000 sequences for each sample, Acidobacteria, Actinobacteria, Proteobacteria and Verrumicrobia were the most abundant bacterial phyla present across all soil samples accounting for 74±4% of the reads. Crop rotation increased diversity of the bacterial community, which was also affected by the fertilization regimen. Reads representing frankiae accounted for 0.1 to 1.0% of all reads, with generally higher percentages in fertilized soils. Reads represented frankiae of clusters 1a, 2, 3, and 4, but also a group of frankiae that could not reliably be assigned to a cultured relative. The results provide evidence of long-term establishment of Frankia populations in soils under different management conditions.

Abi received her Bachelor’s degree in Microbiology from the Bharathidasan University, Tamilnadu, India, in 2006, and a Master’s degree in Biotechnology from Bangalore University- Bangalore, India. She started her Master’s degree in Biology in Dr. Hahn’s lab in 2014, applying next generation sequencing methods and the corresponding bioinformatics tools to analyze microbial community structure in soils


Dissertation Defense


Differential selection pressure among duplicated genes in teleosts

Richard John Nuckels, Jr.

Major Advisor: Dana M. García

Committee Members: Dr. Chris Nice, Dr. Noland Martin, Dr. Karen Lewis & Dr. Jeff Gross

 

Friday, May 11, 2018, 10 AM, 153 SUPP


Gene and genomic duplications provide organisms with new genetic material subject to selection. Using myo5, rab11, and rab27 gene families as models, I examined the evolutionary rate differences among duplicated genes and whether selective forces (e.g. purifying selection or positive selection) could be identified in one or both duplicated gene clades. I used phylogenetic and syntenic analyses along with ancestral chromosomal mapping to identify each duplicate. I then analyzed the duplicates using tests for evolutionary selection at the molecular level. Using a branch site-random effects likelihood test, I found evolutionary rate values (ω) to fall into two or three rate classes along at least one branch for one duplicated gene clade for each of the gene trees created. One rate value (ω1) for a percentage of codon sites was close to zero, representing purifying selection. A second rate value (ω2) for a percentage of the codons was much greater than one (ω2 >>>1), signifying positive selection. The two rate classes were present in the teleost myo5bb branch for the motor domain and the cargo binding domain, and two rate classes were present in teleost myo5ba for the cargo binding domain. Also in teleosts, I found two rate classes for the rab11a branch, rab11a1 branch, and rab27bb. Using sequences from 7-10 organisms that diverged from a common ancestor 140-440 million years ago, I found ω values between 0.01 and 0.24 for the whole coding sequence for duplicated genes ranging in size from 200-220 codons. For longer coding sequences (1915 codons), ω ranged from 0.26 to 0.41. I examined the percentage of invariant codons present in each of the gene clades and found the percentage of codons that were invariant to range from 6% for the highly variable neck region of myo5 to more than 30% for some highly conserved duplicated rab11 and rab27 genes and some highly conserved regions for some myo5 duplicates. I identified a highly conserved ω for codons for amino acids that have previously been linked with the functionality of the Myo5 and Rab proteins. These data lead me to infer that the duplicated genes remain functional or have some modified, acquired functionality that remains to be identified.


Bio: Richard John Nuckels, Jr. was born and raised in Texas with brief stints in Wyoming and Colorado. Richard’s research experience began as an undergraduate researcher using zebrafish as a model to understand the evolution and development of pigment cells. His research continued as a lab manager and graduate student using zebrafish as a model for vertebrate eye development. He completed a B.S. in Biochemistry from UT-Austin and an M.S. in Biology from Texas State University. Upon completing his Ph.D. degree, Richard will continue working as a lecturer and lab coordinator at UTSA where he hopes to continue his research while mentoring students in comparative genomics.


Thesis Defense

INFLUENCE OF VARIABLE PLANTING TIME ON THE PRODUCTIVTY OF A CORN-BEAN INTERCROPPING SYSTEM


Sarah Eisenmenger


Major Advisor: Dr. Susan Schwinning

 

Committee Members: Dr. Nihal Dharmasiri, Dr. Ken Mix

 

Thursday, April 5, 2018, 4:30 PM, Supple Norris Room


Intercropping is an agricultural practice in which two or more crops are grown together. It is employed in many countries to increase yields relative to monoculture, especially when crops are grown without fertilizer and pesticide inputs. Previous research has focused on modifying planting densities and spatial arrangements to optimize intercropping yields. This project focused on optimizing the timing of component crop planting as an additional method for improving the overall yield of a corn-bean intercropping system. Corn-bean intercrops typically overyield (meaning they produce more yield grown together than grown separately), either because bean supports the growth of corn through biological nitrogen fixation, or because the two crops have weak competitive interactions and are less suppressed in the intercrop than if they competed intraspecifically in monoculture. I hypothesized that if the bean-corn interaction is facilitative, earlier planting of bean should increase the yields of both crops. Alternatively, if the interaction is competitive, earlier planting of bean would increase bean yield but lower corn yield with little effect on their combined yield. Beans were seeded 20 and 10 days before, simultaneously with, and 10 and 20 days after corn for a total of five intercropping treatments. Additionally, monocultures of each crop with matching planting dates were grown to calculate the yield advantage relative to monoculture. Final yield data supported the second hypothesis; the intercropping yield advantage was not significantly affected by the bean planting offset, but an earlier bean planting provided greater bean yields and slightly lower corn yields. The experiment suggested that, while it is possible tweek corn and bean yields in the intercrop by varying planting times, this does not appear to be an effective method for optimizing combined yield.


Bio: Sarah was born and raised in San Antonio, TX. She enjoys learning about animals, plants, and insects and grew up spending a lot of time outdoors. After starting out as an English major in college, she found that conservation and the environment were more important to her. She graduated from the University of the Incarnate Word in 2015 with a Bachelor of Science in Environmental Science. Sarah then joined the Population and Conservation Biology graduate program in Fall 2015 to study plant ecology. She has a German Shephard mix named Percy and a bearded dragon named Layla.


Thesis Defense

Host plant affiliation and spatial autocorrelation as drivers of genetic differentiation among populations of a regionally host-specific insect herbivore


Name: Amanda L. Driscoe


Major Advisor: Dr. James R. Ott

 

Committee Members: Dr. Chris C. Nice and Dr. Noland H. Martin

 

Monday, April 2, 2018, 1:00 PM, Norris Room


Disentangling the processes responsible for structuring patterns of biodiversity at all spatial scales challenges biologists as such patterns represent evolutionary and ecological processes coupled with spatial autocorrelation among sample units. The phytophagous insect, Belonocnema treatae (Hymenoptera: Cynipidae) exhibits regional specialization on three species of live oaks throughout its geographic range across the southern USA. Here I ask whether populations of B. treatae affiliated with each host plant exhibit genetic differentiation that parallels host plant phylogeography while controlling for spatial autocorrelation among sampling locations. I used next-generation genotyping-by-sequencing of 1,219 B. treatae collected from 58 sites distributed across the geographic ranges of the three host plants to identify 6,987 common, and 44,390 rare, single nucleotide variants. Population genomic structure was then investigated using a hierarchical Bayesian model to assign individuals to genetic clusters and estimate admixture proportions. To control for spatial autocorrelation when investigating the role of host plant affiliation in determining patterns of among-population genetic differentiation, Distance-based Moran’s eigenvector maps was used to construct regression variables summarizing spatial structure inherent in the sampling design. Redundancy analysis (RDA) incorporating these spatial variables was then used to simultaneously examine the roles of host plant affiliation and spatial autocorrelation in determining patterns of among-population genetic differentiation. RDA confirmed host-associated linages of B. treatae in the eastern portion of the species’ range and clinal host-associated lineages in the west, independent of spatial autocorrelation. These results suggest a linkage between the history of genetic differentiation among host plants and genetic differentiation of the host-associated herbivore populations.


Bio: Amanda earned her Bachelor’s of Science in Animal Science at University of Minnesota, Twin Cities. She joined the Population and Conservation Biology graduate program in Fall 2015.


Thesis Defense

CONSEQUENCES OF LONG-TERM CHANGES IN FISH COMMUNITY STRUCTURE ON ECOSYSTEM FUNCTIONING IN A SUBTROPICAL SPRING-FED RIVER


Aine Carroll


Major Advisor: Dr. Weston Nowlin 

 

Committee Members: Dr. Thom Hardy, Dr. Josh Perkin

 

Monday, April 2, 2018, 12:00 PM, FAB 130


Ecologists have examined and debated about the relationship between biodiversity and ecosystem functioning but have in general found that the functional roles of species within communities affect ecosystem functioning. Biological invasions are globally pervasive and can have potentially deleterious effects on ecosystems because some non-native taxa can establish dominance in biomass or abundance and have a detrimental impact on their introduced environment. Although the effects of non-native taxa have been examined for decades, few studies have utilized a longer-term perspective (> 10 years) to assess how non-native taxa affect ecosystem functioning. In this study, I examined long-term changes in fish community composition in the spring-influenced upper San Marcos River (central Texas, USA) and its ecosystem functioning implications, specifically how temporal changes in the composition and diversity of the fish community were related to changes in the rates and ratios of dissolved inorganic N (NH4+) and P (PO43-) recycled by the fish community and the sequestration of nutrients into fish biomass. I assembled a 76-year data set (1938 – 2016) of fish collections for the upper San Marcos River and linked it to contemporaneous estimates of species-specific nutrient content and dissolved nutrient excretion rates from the upper San Marcos River. Analysis of the fish community indicated three distinct time periods with notable shifts in fish community composition between time periods: 1938 – 1959 (Period I), 1960-1989 (Period II), and 1990 – 2016 (Period III). Patterns in occurrence-weighted biomass indicated that there were substantial shifts in which species had the larger contribution to community-wide biomass (as C, N and P) of the entire fish community, with the proportional contribution of non-native and non-spring associated fishes being the highest in Period II. However, the proportional contribution of non-native and riverine-associated fishes to the community-wide dissolved P and N recycling rates increased across the three periods. This study indicates that, although the upper San Marcos River contains a relatively diverse community containing a large number of native taxa, the relative importance of non-native species in ecosystem functioning has generally increased over time.


Bio: Aine is from Dallas, and moved to Austin in 2007. She earned her bachelor’s degree in English Writing with a minor in Environmental Science and Policy from St. Edward’s University in 2011. She joined the Aquatic Resources graduate program in Fall 2015.


Thesis Defense

Host Plant and Spatial Influences on the Natural Enemy Community Structure of a Host Specific Herbivore


Name: Robert Busbee


Major Advisor: Dr. James Ott, Department of Biology, Texas State University

 

Committee Members: Dr. Chris Nice, Department of Biology, Texas State University, Dr. Noland Martin, Department of Biology, Texas State University

 

Monday, April 2, 2018, 10:00 AM, Supple Science Building, Room 257


Both environmental variation and spatial autocorrelation play roles in structuring communities at all spatial scales. However, untangling the respective contributions of these sources of variation represents a long-standing, complex, and methodologically ever-evolving question for community ecology. Here I investigate the structure of the insect natural enemy community centered on galls produced by Belonocnema treatae (Hymenoptera: Cynipidae) on the leaves of its host plants across the gall former's geographic range while controlling for spatial autocorrelation among sample sites. Belonocnema treatae exhibits regional host plant specialization across the southern US on three live oak species, Quercus fusiformis (Qf), Q. virginiana (Qv), and Q. geminata (Qg). I sampled the natural enemy community at 118 sites by rearing natural enemies that emerged from galls collected at each site. I identified 32,722 natural enemies representing ≥30 taxa from 126,812 galls. I hypothesized that richness and diversity on Qv would exceed that on Qf and Qg since the geographic range of Qv bridges that of Qf to the west and Qg to the east. Contrary to my hypothesis one-way ANOVA followed by a Tukey’s HSD showed that both richness and Shannon-Wiener diversity was greatest on Qf. To disentangle the role of host plant affiliation from spatial autocorrelation among sample sites I conducted a Redundancy Analysis (RDA). I first used Principal Coordinates of Neighbor Matrices (PCNM) to generate explanatory variables representing orthogonal aspects of spatial structure within the sampling frame. The set of PCNM vectors that were significant were then included in a RDA along with the host plant species from which each natural enemy was reared to examine the respective roles of host plant affiliation and spatial structure in determining abundance and species composition of the natural enemy community. This study establishes a significant role for both alternative host plants and geography in structuring the diversity of the natural enemy community of B. treatae and illustrates the advantages of the PCNM & RDA approach.


Bio: Robert earned his Bachelors of Science in Ecology and Evolutionary Biology at Angelo State University. He joined the Population and Conservation Biology graduate program in Fall 2015.


Thesis Defense

Assessing seasonal diets of waterbuck (Kobus ellipsiprymnus) in central Texas


Kaitlin Lopez


Major Advisor: Dr. Thomas R. Simpson

 

Committee Members: Dr. Dittmar Hahn (Co-Chair), Dr. David Rodriguez, Dr. James Gallagher (Texas Parks and Wildlife)

 

Monday, April 2, 2018, 9:00 AM, Supple 153


It is important to understand how different species use food resources when developing wildlife management strategies. This is particularly relevant in Texas where exotic ungulates are frequently stocked outside their native range with other species with which they did not coevolve. To date, no food habit studies have been conducted in Texas for waterbuck (Kobus ellipsiprymnus), a large antelope native to Africa. I investigated the seasonal diets of waterbuck located on Mason Mountain Wildlife Management Area in Mason County, Texas from June 2016 to March 2017. The objectives of my research were to 1) determine the seasonal diets of waterbuck by using microhistological analysis to identify and quantify plant fragments found in fecal material, 2) determine if waterbuck forage selectively, and if so, which foods were used more or less than their availability, 3) use DNA analysis to identify plant DNA extracted from fecal material, and 4) compare the results from both diet analysis techniques. In each meteorological season, I collected 20 freshly deposited fecal samples for diet analyses. To determine if waterbuck were selectivity foraging, I conducted vegetation surveys simultaneously with fecal sample collection to estimate availability of plants. I used the Daubenmire method to quantify available herbaceous vegetation and the line-intercept method to quantify available woody vegetation at 10 different points occupied by waterbuck. DNA analysis targeted the c to h region of the chloroplast trnL (UAA) intron. DNA was not successfully amplified and sequenced from fecal samples. Using microhistological analysis I quantified 47 unique plant species in the diet of waterbuck. To construct the diet, I looked at the number of fragments detected for each species compared to the total number of fragments examined (N = 2000, 500 per season). To determine if plants were utilized more than their estimated availability I performed a log-likelihood chi square test. To further determine forage selectivity, I used Manly’s alpha index of selectivity and constructed 95% confidence intervals around estimate proportions of use for each species consumed. In all seasons, plants were not used proportional to their availability in the environment and waterbuck actively selected their food resources. The bulk of the diet consisted of grasses, most of which occurred in wetlands. My results suggest that resource competition between waterbuck and upland grazers such as gemsbok, sable antelope, and scimitar-horned oryx is minimal. However, competition needs to be considered when stocking waterbuck with cattle or other grazers that regularly utilize riparian species.


Bio: Kaitlin was born in Maryland but moved to McKinney, Texas at the age of two where her passion for animals, bugs, and all things outdoors flourished. In December 2014, she graduated cum laude from Texas State University with her Bachelor of Science degree in Wildlife Biology. Following a brief break from academia, Kaitlin returned to Texas State University to join the Wildlife Ecology graduate program in Fall 2015.  


Thesis Defense

Paleoclimate of the Two Medicine Formation based of leaf physiognomy


Ann Marie Prue


Major Advisor: Dr. Gary Upchurch

 

Committee Members: Dr. Karen Chin (University of Colorado), Dr. Julie Westerlund, and Dr. Noland Martin

 

Friday, March 30, 2018, 10:00 AM, Supple 326


In the last 50 years, methods to study ancient warm climates, like those of the Cretaceous, have yielded new information on climates and their interaction with flora and fauna. One of the effective ways to reconstruct paleoclimates in terrestrial environments is to study the external features of plant leaves, or leaf physiognomy. Features of leaves from different climates have been correlated to mean annual temperature (MAT) and mean annual precipitation (MAP). There are several methods to determine paleoclimates that are based on the modern-day correlations between leaf features and climate parameters. These methods include the univariate methods of leaf margin analysis (LMA) and leaf area analysis (LAA), and the multivariate methods of Climate Leaf Analysis Multivariate Program (CLAMP) and Digital Leaf Physiognomy (DiLP). This study uses these paleoclimate proxies to study the Two Medicine Formation, a famous formation in northern Montana that contains both dinosaur and paleobotanical remains. In addition, the research examines the congruence of different physiognomic methods with each other and with other climate proxies for the Two Medicine Formation and surrounding formations of similar age. This study concludes that the univariate methods give generated temperature estimates that are too low, and a precipitation estimate that is too high. Of the two multivariate methods, CLAMP gives slightly lower temperature estimates and has inconsistencies based on classification of leaf features. DiLP, on the other hand, gives more reasonable estimates based on congruence with other paleoclimate proxies. However, the DiLP image processing of the leaves is more complex and time consuming than that of the other methods. In order to cut the leaf image processing time, a new modified technique of doubling the leaf halves from partial fossil specimens was implemented in this study. Preliminarily results from the doubling halves technique indicates that climate parameter estimates are nearly the same as those described in the original DiLP method.


Bio: Ann Marie is a born and raised Cheesehead from Green Bay, WI. She got her bachelor’s degree in Geology and a minor in Horticulture from the University of Wisconsin-River Falls in 2015. While participating in UNAVCO’s NSF funded summer internship, RESESS, she was introduced to using fossilized leaves to infer paleoclimate by Dr. Gary Upchurch. She joined Dr. Upchurch’s lab in the fall of 2015 to work on a project that combined her two passions: rocks and plants. Upon graduating, Ann Marie plans on returning to Wisconsin to weed her gardens, whack rocks, and join the work force. She eventually plans to continue her education to fulfill her dream of getting a PhD. in Geology.


Thesis Defense

Prevalence of endoparasitic helminths of the small Indian mongoose (Herpestes auropunctatus) on the island of Puerto Rico


Name: Jose A. Martinez III


Major Advisor: Dr. Iván Castro-Arellano

 

Committee Members: Dr. Thomas R. Simpson (Co-Chair), Dr. David Huffman

 

Friday, March 30, 2018, 1:00 pm, Supple 153


The small Indian mongoose (Herpestes auropunctatus; heretofore mongoose) has been widely introduced to islands around the world as a biological control agent. Species targeted for control were various rodents and venomous snakes. Follow-up research has been conducted on the mongoose’s role as a potential reservoir of diseases that might affect man and economically important animals. However, most of previous studies have focused on detecting rabies and leptospirosis, with reports related to endoparasitic helminthes being largely incidental. The only study conducted on Puerto Rico reported no endoparasitic helminths from an examination of 210 mongoose visceral organs. From May 22 to August 12, 2015 I trapped mongoose from 5 sites (cattle farms) on Puerto Rico and conducted standard necropsy techniques to survey for endoparasitic helminthes in the viscera. Each site was trapped for a minimum of 2 weeks, logistics and farm operating hours permitting. Each transect consisted of approximately 50 Tomahawk live traps (20x7x7”, Model #204, Tomahawk Live Trap Co, Hazelhurst, WI). Transect checks took place daily starting at 08:00 for regular intervals of 2 hours (depending on heat every hour) until approximately 1700. Using standard necropsy techniques, the visceral organs and tissues collected from 60 mongooses were: Lungs with attached trachea, heart, liver with attached gallbladder, gastrointestinal tract (esophagus to rectum) with associated mesenteric tissues, and bladder. There were no observable signs of parasitism in the major organs (Heart, liver, lungs, bladder, and gallbladder). My examinations of the gastrointestinal tracts yielded two species of nematodes and one Acanthocephalan. The nematode Skrjabinocapillaria caballeroi was found infecting 65 percent of mongoose stomachs while Physaloptera spp. were recovered from 18 percent of gastrointestinal tracts. The Acanthocephalan Oncicola venezuelensis was recovered from the greater and lesser omentum, fascia of the skin and muscle, small intestine tissues, and the connective tissues of the liver to the diaphragm of 36.6 percent of examined mongooses.


Bio:Jose was born in California but has moved over 30 times since including living and graduating High School in Italy. In 2002 he joined the United States Marine Corps where a passion for wildlife and the outdoors was deeply fostered. In December 2013, he graduated from Texas State University with his Bachelors of Science in Wildlife Biology. Following a short break in South Africa working with large African predators, Jose returned to Texas State and joined the Wildlife Ecology graduate program in Fall 2014.


Thesis Defense

Roosevelt elk response to a newly available foraging pATCH


Aaron McGuire


Major Advisor: Dr. Floyd Weckerly

 

Committee Members: Dr. Clay Green, Dr. Mark Ricca

 

March 30, 2018, 11:00, Supple 153


According to optimal foraging theory, herbivores will use a new foraging patch intensely to become familiar with a new resource. To better understand how herbivores incorporate new habitat into their home range, I examined use by a Roosevelt elk (Cervus elaphus roosevelti) herd in Redwood National and State Parks, California, that was recently given access to a nearby, new foraging patch, the cattle pasture. Cattle and predators, both of which can negatively affect elk spatial patterns, also used the cattle pasture. My study objectives were to examine monthly elk use in the cattle pasture, assess cattle and predator influence on herd use of the pasture, analyze summer and winter movement patterns to assess if forage biomass was more limited in one season, and determine if the herd was using the cattle pasture intensely to become familiar with the resources. I placed six infrared, motion sensitive cameras throughout the cattle pasture from August, 2016, to November, 2017. I followed the herd from dawn to dusk, recorded elk activity, movement (step length), and forage biomass in January, 2017 and 2018. Herd movement was also recorded in July, 2017. I found avoidance between elk and cattle and elk and predators at short temporal and small spatial scales in the cattle pasture. Step lengths were similar between summer and winter months. The herd used the cattle pasture more in January, 2018, than in January, 2017. My finding were inconsistent with optimal foraging theory.


Aaron grew up in Roswell, New Mexico where he found his passion for wildlife and working in the outdoors. He graduated from New Mexico State University in 2010 with his bachelor’s degree in Fish, Wildlife, and Conservation Ecology with a double emphasis in wildlife and fisheries. After getting his bachelor’s degree, Aaron moved to Northwest Wyoming where he worked for the Wyoming Game and Fish Department as a fisheries technician, a wildlife damage technician, and a hunt management coordinator. In 2014, Aaron moved to Bozeman, Montana where he worked for Montana State University as a fisheries technician and a wildlife capture technician. He also worked for Montana Fish, Wildlife, and Parks as a wildlife disease technician and a hunt management coordinator. Aaron moved to San Marcos in the fall of 2016 to pursue his master’s degree in wildlife ecology. Aaron plans to move back up north and become a regional wildlife management biologist for a state agency.


 Thesis Defense

Population Viability of Reddish Egrets (Egretta rufescens) in Texas: A System Dynamics Approach to Conservation and Management of North America’s Rarest Heron


Sarah Durham


Major Advisor: Dr. Clay Green

Committee Members: Dr. Floyd Weckerly and Dr. Steve DeMaso

March 28, 2018, 11:00am, Norris Room


Reddish egrets are a threatened waterbird species that inhabit the Gulf Coast of the U.S. and Mexico, as well as, the Bahamas, Cuba, the Mexican Pacific Coast, and the Yucatan peninsula. The plume trade of the late 1800s drastically reduced global population numbers of reddish egrets. By the 20th century, the species was decimated and possibly extirpated in many parts of its range. While much of the historical range has been recolonized, the reddish egret remains North America’s least abundant heron species. An estimated one-third to one-half of the global reddish egret population occurs in the United States, with Texas having approximately 75% of the breeding pairs. While egret population numbers may be stable or increasing in portions of the range, many factors continue to threaten the persistence of the species. Population viability analyses (PVAs) are a common method of predicting a species’ persistence into some future time. The purpose of developing a population viability analysis for E. rufescens is to identify possible factors impeding the growth of Texas populations. By assessing the relative threat of each contributing factor and identifying vulnerable life stages, a robust PVA can estimate how different management actions may affect population demographics. I found that four-year-old female survivorship during the non-breeding and breeding seasons to be the most influential model parameters. My findings are similar to other studies that have found adult survivorship to be the most influential factor to population growth in other long-lived avian species that mature late. Additionally, I found that both the total and breeding populations are projected to remain stable over the next 50 years. While these results are encouraging, it is important to note that the model does not incorporate habitat or spatial information. These findings suggest that management actions focusing on increasing adult survivorship, such as habitat protection, would be most beneficial to population growth and persistence of reddish egrets in Texas.


Bio: Sarah grew up in the rough and tumble corn fields of central Illinois. She moved to Texas in 2011 and began the Wildlife Biology undergraduate program at Texas State University in the Fall of 2012. Sarah graduated summa cum laude from Texas State University in 2015. She began her master’s work in the Fall of 2015 studying reddish egrets. Her hobbies include knitting and cats.


Thesis Defense

Exploring tradeoffs in alternative life history strategies


Amara Lee Garza


Major Advisor: Chris C. Nice, Department of Biology, Texas State University

Committee Members: Jim R. Ott, Department of Biology, Texas State University

Susan Schwinning, Department of Biology, Texas State University

Friday, March 23, 2018, 9:00 AM, Supple Science Building, Room 153


The evolution of gregarious feeding is an intriguing problem in ecology. It occurs in many phytophagous insects and typically coincides with eggs lain in large clutches. Despite many benefits to gregarious feeding, including accelerated larval growth rates, not all species feed gregariously suggesting disadvantages to gregariousness. To investigate the advantages and disadvantages, I studied a system of two sympatric, congeneric butterfly taxa that employ drastically different oviposition and larval feeding strategies. The Emperor butterflies both lay eggs on Hackberry trees (Celtis laevigata, C. reticulata); the Hackberry Emperor (Asterocampa celtis) lays a single egg and caterpillars feed alone, while the Tawny Emperor (A. clyton) lays a large clutch and caterpillars feed gregariously. To explore whether gregarious feeding drives clutch size differentiation while simultaneously filling in natural history information on Asterocampa butterflies this research addressed the following questions: 1) Is there a difference in emergence in terms of relative abundance of Asterocampa between sexes or species? 2) Do Asterocampa species have an oviposition preference between Celtis (Hackberry) host plants? 3) Do Asterocampa larvae experience enhanced performance in gregarious feeding groups? I predicted that the advantage of gregarious feeding would be realized for A. clyton, where females lay large clusters of eggs. Fruit baited traps were used to capture females. Phenological variation in relative abundance was analyzed with partial correlation coefficients. Female oviposition preference was assessed with a choice experiment with leaves of both host trees. Caterpillar group sizes were manipulated across the two host plant species. The group sizes approximated ranges from nature. Caterpillar performance was measured by average weight gained and proportion of caterpillars reaching their second instar. Oviposition preference was quantified using a Bayesian hierarchical model. Caterpillar performance was analyzed using an ANOVA in R. There were no differences in relative abundance across time. Females of both butterfly species preferred to oviposit on C. laevigata. I found significant differences in weight gained between group size treatments and caterpillar species but not between host species. I also found a significant difference in proportion reaching second instar between group size treatments, caterpillar species and host species. My results indicate a disadvantage to being gregarious and demonstrate that solitary feeding can enhance caterpillar performance; thus, the predicted benefits of gregariousness for caterpillar performance were not observed. The advantages of gregarious feeding were not realized in terms of caterpillar performance but might be related to defense against natural enemies.


Bio: Amara earned her Bachelors of Science in Biology at Saint Edward’s University. She joined the Population and Conservation Biology graduate program in Spring 2014.


Dissertation Proposal Defense

 

Competition of Frankia populations for nodulation and development in soils

 


Spandana Vemulapally
Major Advisor: Dittmar Hahn

Committee Members: Mark Paschke (Colorado State University)

Jeffrey O. Dawson (University of Illinois, Urbana-Champaign)

Robert McLean

David Rodriguez

 

Monday, March 5, 2018, 1:00 pm, Norris Room


Actinorhizal plants exist in symbiotic associations with root-nodule forming Gram-positive actinobacteria of genus Frankia. These filamentous heterotrophic bacteria provide the plants with reduced nitrogen resources through nitrogen fixation. Recent studies in our lab using molecular tools like qPCR and Illumina sequencing to quantify Frankia populations in soil and root nodules suggested large differences between detectable Frankia populations in soil and those in root nodules. The data suggested that root nodule formation was not a function of abundance or relative diversity of specific Frankia populations in soils. Our hypothesis was that the differences were due to alternative traits of the Frankia populations, one of which could be competition between strains in which one strain outcompetes the other for nodule formation even at low abundance. An alternative hypothesis was that it could be growth appearance, in which one strain producing many small fragments with small numbers of cells could provide more nodulation units than another one developing few large colonies with comparatively more cells. We took advantage of the availability of specific pure cultures representing individual clusters or sub-clusters within the genus Frankia and then developed specific quantification methods that allowed us to distinguish and quantify these strains after inoculating in different concentrations and combinations in microcosm studies under controlled conditions. Quantification and characterization of populations in soil and rhizosphere as well as in nodules of the host plant species were done using qPCR and in situ hybridization techniques targeting specific Frankia populations. Using the same techniques, we were also studying host plant effects on competition for nodule formation by representative strains of different Frankia clusters.


Bio: Spandana Vemulapally was born in Andhra Pradesh, India. She graduated with a Master of Science degree in Biotechnology from Texas Tech University in 2012 and a Master of Science degree in Biomedical Sciences from Texas Tech University Health Sciences Center in 2015. She enrolled in the PhD program at Texas State University in Spring 2016.


Dissertation Defense

Plant effects on the dynamics of Frankia populations in soil


Seifeddine Ben Tekaya

Major Advisor: Dittmar Hahn

Committee Members: David Rodriguez

Robert McLean

Jeffrey O. Dawson (UIUC)

Mark Paschke (CSU)

 

March 5, 2018, 8 am, Supple 153

 


Frankiae are slow growing actinobacteria that are able to form root nodules with some woody non-leguminous plants. Studies on the ecology of these bacteria are hampered by difficulties to isolate them into pure cultures which was a prerequisite for quantitative analyses in the past. We have therefore focused on the development of molecular approaches that allowed us to retrieve quantitative data from environmental samples unbiased by the limitations of culturability. A first objective of the current study was to develop qPCR based methods to distinguish groups within the genus and quantify their populations in soil. Additional attempts were made to distinguish and quantify typical, nitrogen-fixing frankiae from atypical, generally non-nitrogen fixing frankiae. Both SybrGreen- and Taqman-based qPCR methods were subsequently evaluated for the quantification of these populations in different soils. These methods are then used to study long term effects of agricultural management practices on abundance and diversity of frankiae. Data from these analyses were contrasted with Illumina sequencing data. Both qPCR and Illumina sequencing methods were also applied in analyses of microcosm experiments aiming to investigate the effects of plants species on indigenous populations of Frankia and relate abundance/diversity in soils to root nodule populations.


Bio: Seif was born in Carthage, Tunisia, in May 13, 1984. He completed a BS degree in Biological Sciences at the University of Tunis el Manar in 2007, and earned an MS degree in microbiology from the same university with a research thesis that focused on the diversity of ascomycetes in high saline lakes in 2009. In 2014, he joined the Ph.D. program in Aquatic Resources at Texas State University.


Dissertation Proposal Defense

Consequences of Artificial Light at Night on the Physiology and Behavior of Amphibians

Zachery R. Forsburg

Major Advisor: Caitlin R. Gabor, Department of Biology, Texas State University, USA

Committee Members:
Andrea Aspbury, Department of Biology, Texas State University, USA
Mar Huertas, Department of Biology, Texas State University, USA
Jenny Ouyang, Department of Biology, University of Nevada, Reno, USA
Edward Narayan, Department of Natural Sciences, Western Sydney University, Australia

Wednesday, February 28, 2018, 4:00 PM, Supple Science Building, Room 376


Artificial light at night (ALAN) is defined as artificial light that alters the natural light dark patterns in ecosystems. ALAN is a growing problem globally as 40% of the World’s population lives in areas continually illuminated. ALAN can have a suite of effects on community structure and is a driver of evolutionary processes. ALAN has been shown to affect the behavior and physiology of many taxa, yet research on how ALAN may affect behavior and physiology in amphibians, the most imperiled vertebrate class, is lacking. ALAN may contribute to stress and ultimately declines of amphibian populations, particularly in urban areas. I propose to examine, through laboratory and semi-natural mesocosm studies, if ALAN is contributing to physiological stress and altering behaviors in amphibians. I will also explore whether exposure to ALAN is affecting growth and survival in tadpoles and potential carry-over effects of ALAN exposure on juvenile frogs. Further, in a mesocosm setting, I will investigate if other variables such as predation and pesticide exposure have synergistic effects with ALAN by measuring growth, behavior, and physiology in tadpoles. Employing a non-invasive water-borne hormone collection protocol will facilitate a repeated measures protocol allowing me to use a reaction norm approach to analyze how hormonal and behavioral traits change over time and environmental gradients. Together, this research will provide new insights into the consequences of ALAN on amphibian populations, and if hormonal responses can evolve in response to rapid human change such as light at night.


Bio: Zach Forsburg grew up in Central Pennsylvania and earned his B.S. and M.S. in Biology from Shippensburg University. Seeking warmer weather, Zach moved to South Florida after graduate school to work at Archbold Biological Station in Venus, Florida, where he collected data on habitat use and movements of gopher tortoises and federally threatened Eastern indigo snakes. Zach was a member of the 2015 Florida Wildlife Corridor Expedition team, a 70-day, 1,000-mile, journey across Florida to bring awareness of conservation needs in Florida. He ended his 6 years at Archbold as the Director of Development and began his PhD studies in 2015. He hopes to be the next Richard Archbold.


Dissertation Proposal Defense

 

Factors influencing riverine community structure of aquatic organisms: implications for imperiled species management


David S. Ruppel
Major Advisor: Timothy H. Bonner, Department of Biology, Texas State University

Committee Members;

Noland H. Martin, Department of Biology, Texas State University

Kenneth Ostrand, U.S. Fish and Wildlife Service, San Marcos, Texas

Jim A. Stoeckel, School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University

Joseph A. Veech, Department of Biology, Texas State University

 

Thursday, February 15,2018, 2:00 PM, Freeman Aquatics Building, Room 102

 


Aquatic communities are structured by selection, drift, dispersal, and speciation processes. Processes collectively interact to generate a diversity in community patterns among riverscapes. Aquatic community patterns and processes can be disrupted by anthropogenic alterations, such as changes in water quality and quantity, introductions of exotics species, and habitat fragmentation. The common theme among the chapters of my dissertation is the identification of patterns that aid in understanding processes (e.g., selection, drift, and dispersal) and conservation status (resiliency, representation, and redundancy) of riverine communities and species. Dissertation chapters will address gaps in existing information necessary to inform individual, population, and range-wide responses to natural and anthropogenic influences using the USFWS Special Status Assessment (SSA) framework for establishing species viability through demonstrated or predicted redundancy, representation, and resiliency. Chapter I will be a fish-habitat community assessment within the upper Red River of Texas and Oklahoma (2-year survey). Chapter II and III will assess life history characteristics and factors influencing instream movement of USFWS candidate species (Prairie Chub), a SGCN species (Red River Shiner), and an endemic species (Plains Killifish). Chapter IV will be mussel distributions and habitat associations, including habitat assessments for several USFWS candidate species, within the Colorado River. Unique contribution of my work is the application of the theoretical community ecology framework to understanding redundancy, representation, and resiliency of local systems with multiple species of conservation concern.


Bio: David was born in Saginaw, Michigan but lived in the quaint town of Ishpeming in Michigan’s upper peninsula for most his childhood. He graduated cum laude with his B.S. in Zoology from Northern Michigan University in 2012. David completed his M.S. in Aquatic Resources in August 2014 studying the effects of instream flow recommendation on larval fish diets in the San Antonio and Guadalupe Rivers. He began as a PhD student in 2015 and plans to complete his PhD in December 2018. Long term goals include obtaining a tenure-track professor position.


Dissertation Proposal Defense

Biofilm Growth and Control in Spaceflight


Starla Thornhill


Major Advisor: Dr. Robert “Bob” McLean Texas State University

 

Committee Members: Dr. Cheryl Nickerson Arizona State University

Dr. C. Mark Ott -NASA Johnson Space Center

Dr. David Rodriguez Texas State University

Dr. Dana Garcia – Texas State University

 

February 02, 2018, 8:00 Am, Norris Conference Room, Supple 376


Biofilm formation in microgravity is largely understudied. At this time, only a few studies of biofilms in microgravity have been published, and in those cases only monoculture biofilms. Environmental biofilms, including those on spacecraft, are polymicrobial communities. The Potable Water Dispenser on the International Space Station (ISS) is host to a persistent biofilm that is resistant to long-term disinfection. Since biofilms cause microbiologically-induced corrosion and release cells into the environment, their presence is a potential risk to the ISS crew. To investigate mixed species biofilms in microgravity environments, biofilms of Escherichia coli and Pseudomonas aeruginosa will be grown in coculture on stainless steel coupons using microgravity modeling high-aspect ratio vessels (HARVs). These bacteria can be differentiated using inserted mCherry (into E. coli) and gfp (into P. aeruginosa) genes. Biofilm structure will be analyzed using confocal microscopy and species composition by qPCR. Boric acid, a biofilm dispersant agent, will be investigated in concert with disinfectants currently in use on ISS to determine their disinfection capability. Microbiologically-induced corrosion on stainless steel will also be investigated using analytical electron microscopy and energy dispersive X-ray spectroscopy. Additionally, an experiment investigating growth, Ag-based disinfection, and corrosion will be sent to ISS for investigation in true microgravity. While in flight, biofilms will be analyzed using epifluorescence microscopy and post-flight analytical electron microscopy. This will allow for a better understanding of the growth and treatment of biofilms on ISS, providing a safer environment for long-term habitation of humans in spaceflight.


Bio: Starla Thornhill earned her BS (Microbiology) and MS (Biology) at Texas State University in 2014 and 2016, respectively. She grew up in Austin, TX. She loves cats and video games. Her research interest is microbiology in spaceflight. She won People’s Choice Award at the University Final 3MT Competition in 2017.

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  • Thesis Defense

    The role of birds as hosts for ticks, vectors of Borrelia burgdorferi, in eastern Texas


    Brian Gold


    Major Advisor: Dr. Ivan Castro-Arellano

     

    Committee Members: Dr. Clay Green & Dr. Maria Esteve-Gassent

     

     

    November 6, 2017, 3:30 PM, Supple Science Building 376-A (Norris Room)

     


    The bacterial spirochete Borrelia burgdorferi, the etiological agent of Lyme disease, an emerging infectious disease in the United States [US], has been detected in previous surveys in Texas. However, the northeastern and midwestern US are currently the areas with the highest abundance of cases of Lyme disease reported. Ticks infected with Borrelia of the genus Ixodes are solely responsible for transmission to humans, though other tick species maintain its persistence in the environment. The distribution of the black-legged tick, Ixodes scapularis, the primary vector of Borrelia to humans in the US includes most of the eastern portion of Texas. While adult I. scapularis ticks feed primarily on large mammals (e.g. deer), the larval and nymphal stages are generalists that will feed on numerous taxa, including small mammals, birds, and reptiles. This project, along with associated tick flagging, mammal, and reptile surveys in eastern Texas were implemented to ascertain how the Borrelia life cycle is structured at the local level in eastern Texas. The focus of my research was on the role that ground-dwelling and foraging birds had on the abundance and distribution of ticks in eastern Texas. The study sites chosen for this project were disturbed and more pristine sylvan habitats at Gus Engeling Wildlife Management Area [GEWMA] and Big Thicket National Preserve [BTNP]. A reference infestation rate of 5.1% was chosen to compare the observed infestation rate. In total, 211 birds were captured over two field seasons, 4 of which were found infested with Ixodid ticks (1.9%). This suggests that birds are not an important vertebrate host group for maintaining tick density at the local level in eastern Texas. Several migratory bird species that have been found in other studies to be important in translocating ticks were captured at each site. A comparison of the alpha and beta diversity at and among each site revealed that the habitats at GEWMA were most similar in composition, though the disturbed habitat at BTNP was the most diverse (H’=2.4840).


    Bio: Brian is originally from Durham, North Carolina and has lived in Texas for the last 20 years. He attended Collin College in Plano, TX and transferred to Texas State University, where he earned a B.S. in wildlife biology in 2014. As an undergrad Brian assisted with small mammal trapping and processing for grad students in Dr. Castro’s disease ecology lab. Brian joined Dr. Castro’s lab in 2015 as a graduate student (M.S. wildlife ecology) seeking to combine his interest in bird community structure and conservation with the lab’s focus on wildlife disease systems. Brian has worked as a bird survey technician for the American Bird Conservancy (Texas), US Forest Service (Oregon), and most recently at Fort Hood, Texas for the University of Illinois-Urbana where he was part of a team that won the USFWS Conservation Partnership Award in June, 2017.


    Thesis Defense

    Reproductive Ecology of Lampsilis bracteata (BIVALVIA: UNIONIDAE)


    Name: L. Ashley Seagroves


    Major Advisor: Dr. Astrid N. Schwalb

    Committee Members: Dr. Weston Nowlin & Dr. Thom Hardy

     

     

    November 6, 2017, 1:00 PM, Freeman Aquatic Biology (FAB) 130 (Seminar Room)

     


     

    Lampsilis bracteata (Texas Fatmucket) is one of fifteen threatened mussel species in Texas. A better knowledge of their reproductive ecology is needed to develop conservation and management strategies. The purpose of my study was to investigate differences in mussel host fish relationships between populations of Lampsilis bracteata and fish originating from the San Saba and Llano River in Central Texas, and to monitor and compare gamete production, gravidity period and viability of their larvae (glochidia) between the rivers. Gamete production, gravidity, and glochidia viability varied with season and were significantly higher in the San Saba compared to the Llano River. Transformation success of glochidia to juveniles differed significantly between host fish species, and on some fish species glochidia tended to transform better when they originated from the same river. The results of this study suggest that propagation efforts that are currently initiated in Texas should consider ecological differences between populations. Further investigations of the life-history strategies of Lampsilis bracteata and other mussels are warranted before augmentation and reintroduction efforts are initiated.


    Bio: Ashley is a proud native to central Texas who developed a love for water at a young age. She graduated in 2014 with a B.S. in Wildlife Biology from Texas State University after dipping her toe into the world of aquatic ecology by working as an undergraduate researcher. She went on to use her knowledge of wildlife and fisheries as a research technician before beginning her Master’s degree. In her time at Texas State University she was selected as a recipient of the Chuck Nash Aquatic Studies Scholarship in 2016 and 2017, and was awarded Best Student Poster at the 2017 annual meeting of the Texas Chapter of the American Fisheries Society. She would now like to pursue a career in freshwater ecology, and cannot get enough of these crazy critters that we call freshwater mussels. She would like to thank all of her friends and family for their support—including her trusty and snuggly dog friend, Mr. Jack.

     


    Thesis Defense

    Development of a rapid diagnostic test for detection of Streptococcus mutans in saliva for dental caries diagnosis


    Name: Kelly L. Braddock


    Major Advisor: Dr. Shannon Weigum

     

    Committee Members: Dr. Robert McLean, Dr. John Carrano

     

    Monday, November 6, 2017, 8:00 AM, Supple Science Building 257


    The personal and financial impact of common and often overlooked oral diseases, such as dental caries, is sizable and prevalent throughout the world. Rapid diagnostic tools continue to be developed to prevent, diagnose and monitor treatment responses of a variety of diseases including, dental caries. This assay, like many other point-of-care diagnostics, is based on the lateral flow immunoassay design. Initial development required identification of two antibodies that specifically recognize antigens on the surface of Streptococcus mutans, and are compatible as a matched pair. To identify a matched pair, antibodies were first purified from hybridoma cell culture supernatant, by affinity chromatography, and screened against two S. mutans strains of differing serotypes. The two hybridoma cell lines for which antibody was successfully purified, were screened and both indicated activity against one S. mutans strain of the most common serotype, serotype c. However, only one of the purified antibodies was able to recognize the non-serotype c strain. Further assay development focused only on the strain of S. mutans recognized by both antibodies. Conjugation to biotin allows the detection antibody to form a complex with the reporter molecule HRP, which is conjugated to streptavidin. A portion of both antibody stocks were conjugated to biotin and each of them was tested in both the detecting and capture positions, in order to determine the optimal orientation of the matched pair. Only one orientation recognized S. mutans within the lateral flow assay. Initial experiments indicated that the lower limit for S. mutans detection was within the clinically relevant range, for which concentration of salivary S. mutans can be used to diagnose dental caries. After identifying a matched pair, detergent concentration as well as blocking conditions were optimized. To assess analytical performance within a realistic matrix, a dose response curve was created from samples made in human pooled saliva. The dose response indicated results of the assay at varying concentrations were reproducible, but detection of S. mutans occurred only at concentrations much higher than in previous testing. This discrepancy is likely due to matrix effects within saliva, including presence of endogenous proteins and high viscosity. Future testing to optimize the assay within saliva, may improve its detection capabilities by mitigating some of these matrix effects, through addition of detergents or mucolytic agents.


    Bio: Kelly was born in Louisiana and raised in Central Texas where she spent most of her childhood playing soccer. After earning a B.S. in Biology from Texas State University in San Marcos, she decided to pursue a M.S. focusing on microbiology and their detection by point-of-care diagnostics. Kelly hopes to continue her career in the point-of-care diagnostics field.


    Dissertation Defense

    Epigenetic regulation of the defense gene induction in Arabidopsis thaliana in response to Pseudomonas syringae


    Name: Yogendra Bordiya


    Major Advisor: Dr. Hong-Gu Kang

    Committee Members: Dr. Nihal Dharmasiri (Dept. of Biology, Texas State University)

    Dr. Sunethra Dharmasiri (Dept. of Biology, Texas State University)

    Dr. Daniel F. Klessig (Boyce Thompson Institute, Cornell University)

    Dr. Ping He (Department of Biochemistry, Texas A&M University)

     

    November 3, 2017, 2:00 PM, Supple 116


    Plants and animals respond to ever changing environment by making changes in the physiological level of various proteins and metabolites. The rapid physiological change to the environment is achieved by massive transcriptional reprogramming. Therefore, switching the large number of genes on and off at the right time in the right place requires highly sophisticated transcriptional regulation and is very important in mounting responses appropriate for the environmental change/stress. Recent studies begin to suggest that epigenetics is one of the critical components in the regulation of transcription to help responding and adapting to environmental changes/stresses. The epigenetic regulation of transcription is achieved through the modification of the chromatin structure, which is generally mediated by DNA/histone modifications, small RNAs (sRNAs), long non-coding RNA, and nucleosome positioning. In my dissertation, I have studied the role of epigenetic components which regulate defense responses in Arabidopsis thaliana in response to Pseudomonas syringae. To this end, I assessed biotic-stress-triggered changes in chromatin accessibility and characterized several epigenetic mutants in gene silencing in Arabidopsis. From these assessments, I particularly focused on testing the hypothesis that these epigenetic changes are important in the induction kinetics of defense genes triggered by infection. Intriguingly, I found that biotic-stress-triggered chromatin changes were frequently associated with transposable elements (TEs) proximal to defense genes, some of which functioned as transcriptional enhancers. This observation suggested that a TE controlling mechanism(s) might be important in defense responses. Indeed, I found that more than a hundred of TEs become transcriptionally induced under biotic stress, which justified further characterization of mutants involved in RNA-dependent DNA methylation (RdDM), the best characterized regulatory mechanism for TEs. I chose to characterize four DCL (dicer-like) genes that are important in the biogenesis of sRNAs, critical modulators for TEs and chromatin remodeling. Among these dcl mutants, dcl1 displayed the most compromised resistance and induction of defense genes against avirulent P. syringae, suggesting that some sRNAs may be necessary for the rapid defense responses. In contrast, dcl2 and dcl3 showed marginally enhanced resistance and elevated expression of defense genes to the avirulent pathogen. In particular, dcl2 and dcl3 showed substantially increased expression of defense genes without pathogen challenges, suggesting that DCL2/3-generated sRNAs are important in suppressing defense genes. Note that the expression analysis of defense genes was performed using a novel targeted RNA-seq known as RASL-seq (RNA-mediated oligonucleotide Annealing, Selection, and Ligation with next-generation sequencing) on defense genes. Selection of the defense genes was based on my RNA-seq analysis, which identified rapid induced genes at different time points in response to avirulent P. syringae as compared to virulent counterpart. In addition to altered defense gene induction in the mutants, I also found that many RdDM genes including morc1/2 were transcriptionally suppressed as early as 6 hr post infection, suggesting a dynamic nature of these epigenetic components in defense responses. Based on the presented observation, I have described a model how defense responses are epigenetically regulated and discussed the implication of this regulation in the evolution of resistance traits.


    Bio: Yogendra received bachelor’s degree in Agricultural Science in 2009 from the University of Agricultural Sciences Bangalore, master’s degree in Crop Science and Biotechnology in 2012 from Seoul National University and started doctoral research with Dr. Hong-Gu Kang at Texas State University in August 2012.


    Thesis Defense

    Effects of urbanization on the relative abundance of hummingbirds (Archilochus alexandri and Archilochus colubris) as measured by

    resource removal rates.


    Name: Caley Zuzula


    Major Advisor: Dr. Joe Veech

    Committee Members: Dr. Jennifer Jensen (Geography), Dr. Jeff Troy (Temple College, Temple, TX)

     

    November 3, 2017, 1:00 PM, Supple 153


    Urbanization leads to loss of natural habitat, an increase in impervious surfaces, and sometimes an increase in the provisioning of artificial food sources for local wildlife. One common scenario of supplemental feeding includes artificial nectar feeders placed out for hummingbirds, typically within suburban neighborhoods. These can be so successful at attracting hummingbirds as to cause an increase in local density. Thus intermediate intensities of urbanization could have an indirect positive effect on hummingbirds. While previous studies have investigated persistence of hummingbird populations across an urban-rural gradient, my study is the first to examine removal rates of resource (sucrose solution) from hummingbird feeders as a proxy variable for relative hummingbird abundance. I deployed nectar feeders (N=27) in locations encompassing various intensities of imperviousness (percent impervious surface as an indicator of urbanization intensity) and canopy cover around San Marcos, Texas, USA, to determine whether these factors affect removal rates of sucrose solution by Archilochus alexandri and Archilochus colubris at 100, 200, and 400 m spatial scales. Canopy cover was presumed to roughly indicate the availability of habitat. Data were collected in Summer 2016 and 2017. Extraneous variables including Julian date, resource availability (ornithophilous plants), precipitation, and temperature were examined, but none of these individually had an effect on solution consumption (p > 0.05). Imperviousness had a significant negative linear effect on solution consumption across all three spatial scales, indicating that hummingbirds become increasingly less abundant with an increase in urban development (p < 0.05). Canopy cover had a non-significant effect (p > 0.1) on solution consumption at all spatial extents. In addition to developing a reliable method for surveying hummingbirds, my findings show that urbanization, despite warmer local temperatures and increased food provisioning, may negatively affect some hummingbird populations.


    Bio: Caley was born and raised in San Antonio, Texas. She started appreciating wildlife in elementary school after catching some tadpoles and raising them to frogs. After high school, she attended Hendrix College in Conway, Arkansas, where she earned her Bachelor's degree in Biology. During college, she developed a deep interest in ecology and evolution through various experiences, including undertaking an animal care internship at the San Antonio Zoo, studying tropical ecology in Costa Rica, doing bioinformatics research on colorectal cancer, and learning about human evolution by studying Paleolithic caves in western Europe. Upon graduating college, she worked as a naturalist at the University of Georgia's satellite campus in Monteverde, Costa Rica, where she taught people from around the world about rainforest ecology. Before starting graduate school at Texas State, she worked as an education intern at the Bamberger Ranch in Johnson City, where she gained hands-on experience about ranch management. In addition to working on her Master's degree, she teaches undergraduate labs and works at Texan by Nature, a wildlife nonprofit organization based out of Austin. In her free time, Caley enjoys hiking, birding, insect collecting, and cooking.


    Thesis Defense

    Characterization of the IBR5-PAD1 Interaction in Arabidopsis Auxin Response


    Name: Nicholas Siepert


    Major Advisor: Dr. Nihal Dharmasiri

    Committee Members: Dr. Sunethra Dharmasiri, Dr. Hong-Gu Kang, & Dr. Dana Garcia

     

    November 2, 2017, 5:00 PM, Supple Science Building 376-A (Norris Room)


    Plant hormones utilize the ubiquitin-proteasome system (UPS) to modulate the expression of specific genes involved in various developmental processes as well as responses to environmental stress. In this process the target proteins are polyubiquitinated by a multi-subunit E3 ubiquitin ligase complex, essentially tagging the target proteins for degradation by the 26S proteasome. One specific type of E3 ligase, the SKP1-CULLIN1-F-BOX protein (SCF) complex, is utilized by several plant hormones to ubiquitinate target proteins. This process is highly specific and requires multiple levels of regulation which are not fully understood. Recent studies have shown that the INDOLE-3-BUTYRIC ACID RESPONSE5 (IBR5) gene, which encodes a dual specificity phosphatase, plays an important role in the auxin signaling pathway. IBR5 negatively regulates Aux/IAA repressor protein degradation, and has been shown to interact with the SKP1 (ASK1 in Arabidopsis) component of the SCF complex. Additionally, IBR5 has been shown to interact with a variety of stress response and signaling proteins such as HSP90 and MPK12. This research identifies and characterizes a novel interaction between IBR5 and PAD1, a subunit of the 20S core of the proteasome. The interaction between IBR5 and PAD1 was confirmed in vitro and in vivo. Additionally, specific domains or regions of each protein were identified to be crucial for this interaction. Characterization of the IBR5-PAD1 interaction provides new insights into the potential function of IBR5 in SCF E3 ligase-mediated protein degradation. Furthermore, IBR5 and PAD1 mutant analysis revealed similarities in auxin-related phenotypes, suggesting a functional connection between IBR5 and PAD1.


    Bio: Nick grew up in central Texas, and was a member of the first graduating class of Manor New Technology High School. This school system focuses on project-based learning and preparing students for STEM fields. While attending Texas State University, Nick developed an interest in molecular biology and joined the Dharmasiri lab in the spring of 2014. He received the Francis Rose Undergraduate Award for Excellence in Biological Research to help fund his work. In the fall of 2014, Nick earned a B.S. in Biology with a minor in Biochemistry from Texas State University. He went on to join the M.S. program in Biology at Texas State University, continuing his research into plant hormone signaling. Nick is currently exploring job opportunities in the biotech industry.


    Thesis Defense

    DETECTING THE PRESENCE OR ABSENCE OF ALTERNATIVE SPLICING OF THE SUPERKDR LOCUS IN HORN FLIES, HAEMATOBIA IRRITANS


    Name: Gabriela Solis


    Major Advisor: Dr. Ivan Castro-Arellano

     

    Co-Advisor: Dr. David Rodriguez

     

    Committee Member: Dr. Dana Garcia

     

     

    Wednesday, November 1, 2017, 9:00 am, SUPP 257


    Changes to pest control efforts are dependent on interactions between insecticides and the pests they target. Horn flies (Haematobia irritans) are agricultural pests that cause economic losses owing to their effect on cattle and their resistance to insecticides. The Superkdr locus is a single nucleotide polymorphism from Thymine to Cytosine resulting in an amino acid change from Methionine to Threonine. This specific mutation has been associated with pyrethroid-resistance in horn flies. In the houseflies (Musca domestica), the superkdr locus was discovered to occur on mutually exclusive exons, exon C and exon D. The purpose of my research is to determine if alternative splicing is occurring at the superkdr locus of horn flies. I used two different methods to determine the presence or absence of alternative splicing. The first method involved sequence analysis of the sodium channel gene containing the superkdr locus. cDNA and genomic DNA were cloned, sequenced, and compared using MacVector. The second method used a single-nucleotide polymorphism (SNP) assay to perform genotyping via real-time PCR. The SNP assays allowed me to genotype the superkdr locus in cDNA and genomic DNA, and simultaneously detect alternative splicing if the locus was not detected in cDNA. I found no significance difference between the genotype of the superkdr locus in genomic DNA compared to cDNA. If alternative splicing of the superkdr locus is occurring, it seems to be rare.


    Bio: Gabriela Solis was born and raised in Laredo, Texas. In 2015, she earned a B.Sc. in Biology with a minor in Chemistry from Texas State University. As an undergrad, Gabriela gained research experience by interning with USDA-ARS working with cattle fever ticks and Porcine Reproductive and Respiratory Syndrome. She decided to pursue a M.Sc., and in Fall 2015 joined the Castro and Rodriguez lab at Texas State. Gabriela hopes to continue her education by pursuing a dual degree in DVM and PhD.


    Thesis Defense

    Distribution of the Texas kangaroo rat (Dipodomys elator) in Texas, with comments on microhabitat, habitat, and habitat modeling


    Name: Silas Ott


    Advisor: Dr. Joe Veech and Dr. Randy Simpson (co-advisors)

    Committee Members: Dr. Ivan Castro-Arellano, Dr. Clay Green

     

    October 27, 2017, 9:00 AM, Supple 257


    The Texas Kangaroo Rat (Dipodomys elator) is a species of conservation concern in Texas with sightings in only seven counties in the past 30 years. The decline of D. elator has been attributed to habitat loss, although its exact habitat requirements have not been determined. Habitat studies have focused on microhabitat and burrow associations but have failed to create an accurate landscape level habitat model. Multiple species within the genus Dipodomys have demonstrated strong associations with certain soil and land-cover types. My goal was to determine which soil and land-cover types are associated with D. elator and then use these associations to model potential habitat across their historic 11-county range. During the summers of 2016 and 2017, I surveyed with spotlights at night for D. elator on public roads throughout its historic range. I found the species at 75 and 63 locations in 2016 and 2017, respectively, among five counties. For analysis, random points were generated along the roads surveyed in 2016 to create a dataset of points representing species absence. A two-group randomization test was used to determine if percent composition of soil and land-cover types (within 150 m buffers surrounding the points) were significantly different between 2016 presence and absence points. Presence points had a significantly greater proportion of mixed grass/shortgrass prairie (P < 0.1), cropland (P < 0.05), clay loam and loam as the topmost soil layer (P < 0.05), and friable clay as the underlying soil layer (P < 0.05) than did absence points. Based on these results, a potential habitat model (map) was created using ArcGIS. This model portrays a much more restricted range than that shown by previous modeling efforts; < 30% of the 11-county area is potential habitat. Given its very limited range, habitat specificity, and potentially small population sizes, D. elator should be monitored carefully with the possibility of establishing populations in protected areas


    Bio: Silas was born in Takoma Park, Maryland, but moved to Texas as soon as he could, growing up in the countryside of the Devil’s Backbone. Since a young age, Silas has had a fascination with flora and fauna of all forms, naming plants and animals as soon as he started talking and reading every field guide he could get his hands on as soon as he learned to read. As a young adult, Silas knew his future career would involve biology in some aspect. As an undergraduate at Texas State, Silas worked in multiple labs assisting with both field and lab work in addition to being the instructional assistant for two senior level courses. He also has worked for the Lower Colorado River Authority as a nature education and recreation facilitator. As a graduate student, Silas has spent the last two summers chasing kangaroo rats around north Texas and has also worked as a biological survey contractor for multiple projects. Silas hopes to start his career as a field technician so that he can be paid to travel around the United States. and continue his adventures in the great outdoors.


    Thesis Defense

    EVALUATING THE DETECTION OF SEASONALLY PRESENT, POND-BREEDING AMPHIBIANS USING ENVIRONMENTAL DNA: A CASE STUDY WITH THE HOUSTON TOAD (Bufo [=Anaxyrus] houstonensis)


    Name: William Keitt

     

     

    Committee Members: Dr. Dittmar Hahn, Dr. David Rodriguez

     

    Tuesday, October 31st, 2017, 8:00 AM, Supple Science Building 376-A (Norris Room)


     

    Molecular survey techniques focusing on the detection of species via environmental DNA (eDNA) are increasingly being implemented for the detection of a wide breadth of animal taxa. Despite increasing use, relatively few studies have evaluated this method for seasonally present pond-breeding amphibians. This study seeks to provide an evaluation of the efficacy of eDNA surveys for the detection of one such species, the Houston toad (Bufo [=Anaxyrus] houstonensis). The Griffith League Ranch (GLR), a primary recovery site in Bastrop County Texas, was sampled weekly during the Houston toad breeding season from February to June of 2016 and sporadically in the spring of 2017. Nine perennial ponds on the GLR were surveyed and 557 water samples were collected for eDNA analysis, with 217 representing known positive controls collected from buckets containing each life stage of this amphibian. Samples were collected following a USGS approved protocol (Goldberg et al. 2011). Both PCR and nested PCR assays were used to assess Houston toad detection/non-detection based on positive amplification of a diagnostic fragment of mitochondrial DNA. PCR assays successfully showed amplification of Houston toad eDNA in 82% of known positive controls, while only 1.1% of eDNA samples from the sampled ponds, and none of the eDNA samples from known positive ponds showed amplification. Nested PCR assays proved more efficient, detecting Houston toad eDNA in 86% of all known positive control samples, 7.4% of all pond samples, and 14% of the known positive pond samples. Our results suggest that these PCR-based detection methodologies for eDNA incur false negative detections, and therefore, are likely less reliable than current survey approaches. The inability of eDNA surveys to accurately detect species presence may be impacted by a variety of factors ranging from environmental inhibitors to lack of assay sensitivity. Therefore, I offer many critical considerations for the implementation of this monitoring strategy in the detection of elusive, seasonally present, pond-breeding amphibians.

     


    Bio: William Keitt was born in northern Virginia and moved to Corpus Christi, Texas at a young age. In 2014, he earned a B.Sc. (AG.) in Animal Science from Texas State University which he used to promptly get a job in a non-agricultural based field as a laboratory technician in Austin, Texas. He decided to pursue a M.Sc., focusing on molecular genetics, and returned to his Alma Mater, joining the Forstner lab in the Fall of 2015. William’s career interests lie in the field of pharmacogenomics, where he hopes to continue developing his skills as a geneticist, and use biotechnology to improve patient care.


    Thesis Defense

    SURVEYING MIXED-SPECIES WATERBIRD COLONIES WITH UNMANNED AERIAL SYSTEMS (UAS): VISIBILITY BIAS, DISTURBANCE, AND PROTOCOL RECOMMENDATIONS


    Jarred Barr

     

    Major Advisor: Dr. M. Clay Green

     

    Committee Members: Dr. Stephen J. DeMaso and Dr. Thomas B. Hardy

     

    Thursday, 19 October 2017, 9:00AM, Supple Science Building 376-A (Norris Rm.)


    Surveys of colonial-nesting waterbirds are necessary for assessing population trends, gaining insight into wetland ecosystem health, and even determining the impact of natural disasters and other environmental concerns. The popularity of unmanned aerial systems (UAS) for use as a survey tool has risen in the past decade, but little research has been conducted on the effectiveness of such technology. I investigated visibility bias and disturbance impacts associated with using UAS to survey waterbird colonies in Texas, specifically in cypress-tupelo watershed and coastal island habitats. I used a stratified random design to place “colonies” of four different decoy types in each habitat, and had six observers independently count decoys from aerial imagery obtained with a consumer-grade UAS (DJI Phantom quadcopter). I used generalized linear mixed-effects models (GLMMs) with a Poisson error distribution to estimate detection probabilities of each decoy type. Black skimmers were the only decoy type at the dredge-spoil island to have a detection probability of significantly less than 100% (0.54 [0.44–0.63 CI], P ≤ 0.001). Detectability of both white- and dark-plumaged herons decreased considerably in the canopied cypress-tupelo habitat when compared to dredge-spoil island (by 80 and 84%, respectively). I investigated disturbance to waterbirds by setting up video cameras at the periphery of active nesting colonies while surveying with unmanned aircraft. I tested the effects of two UAS types on the behavioral reactions exhibited within four active colonies in Texas, and reactions were tallied in 1-minute sampling periods for each nesting colony. These data were used to estimate GLMMs for vigilance and flush behavior. I found that the DJI Phantom quadcopter significantly increased vigilance for 3 of the 4 survey altitudes tested. Vigilant reactions increased in magnitude by 72, 119, and 118% for survey altitudes of 91, 61, and 46 m, respectively. Flush reactions were not influenced by either UAS type or any altitude flown. My results suggest that managers should employ UAS surveys on clear days in high-visibility habitats, or otherwise use another survey method to supplement photographic counts obtained by UAS. In addition, surveys should be flown between 46–91 m only when high resolution imagery is needed (e.g. for abundance estimates) to mitigate disturbance. Even though the Phantom UAS caused increased vigilance, if surveys are done promptly and in back-and-forth transects, the impact of this increased behavior is likely negligible especially when considering the much more harmful effects of ground-based survey methods.


    Bio: Jarred Barr was born and raised in Trabuco Canyon, California. In 2009, he earned a B.Sc. degree in Wildlife Biology from Humboldt State University, and shortly thereafter worked as a field biologist for various agencies. From 2012–2015 he worked as an Ecologist for US Geological Survey, helping monitor the nests of numerous waterbird species in the wake of a large-scale restoration project for the San Francisco Bay. He decided to pursue a M.Sc., and in Fall 2015 joined the Green lab at Texas State. Jarred hopes to continue as a conservationist/ecologist in some capacity, and hey, if he can get paid while doing that, that’d be cool too.


    Dissertation Proposal


    Determining the status and distribution of the Eastern Black Rail (Laterallus jamaicensis jamaicensis) in Texas


    Amanda Moore


    Major Advisors: Floyd Weckerly and Clay Green, Department of Biology, Texas State University  

    Committee Members: Thom Hardy, Department of Biology, Texas State University; Chris Butler, Department of Biology, University of Central Oklahoma; Paul Leberg, Department of Biology, University of Louisiana Lafayette  

    Friday, September 1, 2017, 9:00 am, Supple 257


    The enigmatic Black Rail (Laterallus jamaicensis) is often regarded as the most secretive marsh bird in North America. The Eastern Black Rail (L. j. jamaicensis) may be the most endangered bird species along the Atlantic and Gulf coasts of North America, as it is listed as endangered in six eastern states and is a candidate for federal listing. Texas represents a knowledge gap critical to the development of the species status assessment (SSA) needed for the proposed listing rule in the Federal Register (to be published September 2018). Determining the status of a species or its populations is an arduous task but there are some principles that can help inform conservation efforts: resiliency and redundancy. The objective of my research is to assess the current status of the Eastern Black Rail in the state of Texas, specifically in terms of resiliency and redundancy of rail populations. I hope to better understand Black Rail habitat requirements in Texas by examining home range size, movements, and habitat selection through the use of radio telemetry, and use occupancy-detection data obtained from standardized surveys to develop species distribution models for the Black Rail along the Texas coast.


    Bio: Amanda spent her formative years in Illinois and moved to Texas at the ripe old age of 21. After attending UT San Antonio for two years she relocated to Dallas where she graduated from UT Dallas with a B.A. in art & technology. Working office jobs for the next few years led to a dull existence so she decided to follow her heart and peruse a graduate degree in wildlife ecology at Texas State and study birds.


    Dissertation Proposal


    "The impact of dispersal assessment methods on the resulting management interpretations of endangered species stewardship"

     


    Shashwat Sirsi


    Major Advisor: Michael R. J. Forstner, Department of Biology, Texas State University   

    Committee Members: David Rodriguez, M. Clay Green, Department of Biology, Texas State University.

    Yongmei Lu, Department of Geography, Texas State University

    Michael L. Morrison, Wildlife and Fisheries Sciences, Texas A&M University, College Station, Texas

    Brian J. Halstead, U.S. Geological Survey, Western Ecological Research Center, Dixon, California

    Wednesday, August 23, 2017, 2:00 pm, Supple 257


    Movement in animals play a major role in determining the fate of individual organisms as well as the structure and dynamics of populations. Effective stewardship of animal populations needs to be cognizant of an accurate determination of individual movement rates. A large array of techniques are available to determine movements of individual organisms and thereby, the connectivity between groups of interbreeding individuals. However, it is not clear that the limitations or benefits to management decisions among the techniques have been synthetically analyzed. This is critical given the pace of modern urbanization and the increasing pressures placed on animal populations by human infrastructure impacts requires management decisions for mitigation. Three major frameworks enable the determination of movement rates, i.e. capture-mark-recapture, telemetry, and population genetics. The central theme that underpins this research is that a comparison of dispersal ranges from different data sources will likely reveal biases in consequent management or regulatory approaches. My research will first attempt an analytical review across taxa to demonstrate such biases and differences inherent to each study framework. I will then attempt to establish evidence of framework-specific differences in comparing estimates of movements for the Rio Grande Cooter (Pseudemys gorzugi) and in using potentially disparate framework-specific movement estimates in a broad-scale determination of availability, suitability, and connectivity of habitat for the endangered Houston Toad (Bufo [=Anaxyrus] houstonensis). Both species occur in highly-modified landscapes and approximating true individual-level dispersal increases chances of recovery through management decisions applied at an appropriate scale.


    Bio: Shash is from Bangalore in southern India. He graduated with a Bachelor’s degree in Environmental Sciences and subsequently earned a Master’s Degree from the University of Kent at Canterbury, UK. He worked for an NGO that attempted freshwater turtle recovery for over 8 years. This short stint at attempting conservation without a true understanding of research and study design led him to pursue a PhD at Texas State University.   

     

  • Thesis Defense

    BRIDGING THE GAP: ATTEMPTING TO INCREASE LANDSCAPE CONNECTIVITY USING WILDLIFE CORRIDORS IN THE LOST PINES ECOLOGICAL AREA OF TEXAS


    Payton Prather

    Major Advisor: Dr. Michael R. J. Forstner

    Committee Member: Dr. Shawn F. McCracken & Dr. Thomas R. Simpson

     

    Thursday, August 3, 2017, 2:00 pm, Norris Room


    Artificial wildlife corridors are a potential solution to mitigating wildlife-motorist collisions and maintaining habitat connectivity. Such structures are components toward conservation stewardship of both species and landscapes. The Lost Pines region is home to the endemic, and endangered, Houston Toad.  These structures serve as mitigation efforts to allow the Houston Toad and other wildlife a safe passage among habitat patches despite barriers to dispersal.

    Highway 290 in Bastrop County bisects critical habitat of the endangered Houston Toad.  Wildlife corridors have now been installed (December 2016) at locations based on previous data indicating areas of high wildlife traffic. My study applies a suite of monitoring techniques to determine usage of artificial wildlife corridors along section the roadway. Monitoring techniques include camera trapping and wildlife mortality surveys (walking and driving). In order to determine usage of these corridors, camera traps were placed at the opening of each culvert. Wildlife mortality surveys along the roadway seek to determine areas of high density, and examine mortality densities post-installation of corridors.  I compared wildlife mortality observations found in the construction area during construction and post-construction. These results show no difference in mortality observations between treatments. However, there is a significant difference in observations between survey methods (walking vs driving). I also monitored each wildlife-crossing structure and remaining culverts for usage by wildlife. Camera traps at the both WCS resulted in low observations of utilization by small mammals with high usage outside each structure. Track pads yielded similar results with both small and large species currently utilizing these structures. Continued monitoring is imperative in order to determine long term impacts of WCS and their resulting potential change on wildlife mortalities along this highway system.


     Bio:  Payton is originally from El Campo, Texas and received a B.S. in Wildlife Biology from Texas State University. Payton began working in the Forstner lab in the pursuit of his undergraduate degree assisting with management projects for the endangered Houston Toad. Upon completion Payton began his Master’s of Science in Wildlife Ecology at Texas State University in the Forstner lab in the Fall of 2016. His research interests involve conservation management and stewardship of endangered and threatened species. Payton is supported by his wife Lauren and daughter Freya.

     

    Thesis Defense

    INLUENCE OF INDOLE AND MIXED CULTURE GROWTH ON PSEUDOMONAS AERUGINOSA BIOFILM STRUCTURE
     


    Name:  Ernesto Valenzuela, Jr.


    Major Advisor: Robert JC McLean              

    Committee Members: Gary M Aron, Stacie Brown (Southwestern University)

     

    Date: Thursday July 6, 2017, 10:00am, Supple 153


       When microorganisms are studied within their natural environments, they are not commonly found as single species.  Microbes are usually found as clusters or multitudes of aggregates within surface-attached biofilm communities. The discovery of this sessile lifestyle has had a resounding effect on the scientific community and the approach toward studying anti-microbial resistance (AMR).  Past studies showed that quorum sensing (QS) mutants of Pseudomonas aeruginosa, unable to produce N-acylated homoserine lactone (AHL) signals had altered biofilm structure. During mixed culture growth of P. aeruginosa with Escherichia coli, we found that E. coli production of the organic compound, indole, inhibited AHL-regulated genes in P. aeruginosa. The current study was conducted to see if mixed culture growth of P. aeruginosa with indole-producing E. coli affected biofilm structure.  Two wt Pseudomonas aeruginosa strains, PA14 and PAO1 were co-cultured with wt Escherichia coli BW25113 (indole producing), and E. coli tryptophanase mutant tnaA (non-indole producing).  Comparably, exogenous indole was added in multiple concentrations (mM) in order to try and monitor the response of the P. aeruginosa strains.  P. aeruginosa pqs mutant strains where also studied in order to see if indole induced similar effects in a non-AHL mediated QS system.  At lower concentrations (0.1mM), indole induced a spike in growth rates and genes geared toward virulence mechanism of P. aeruginosa.  In contrast, higher concentrations (0.5 or 1mM), overall induced downregulation of virulence mechanisms controlling, pyocyanin, rhamnolipids, and elastase production, inhibiting quorum sensing. However, there was no obvious change in biofilm structure at any of the indole concentrations tested.


    Bio:  Ernesto Valenzuela, Jr. was born October 13, 1979 in Caldwell, Texas.  Also known as the "Original Kolache Capital of Texas".  He relocated to Little Rock, Arkansas where he attended The University of Arkansas at Little Rock, while working as a research technician in Biochemistry and Molecular Genetics at The University of Arkansas for Medical Sciences.  He would graduate with honors as a Ronald E. McNair Scholar, completing a bachelors in Biology with a minor in Environmental Health Sciences.  Upon graduation he managed a medical-based research laboratory in Toxicology & Pharmacology at The University of Arkansas for Medical Sciences before deciding to pursue graduate work at Texas State University under Professor R.J.C McLean.

     


    Thesis Defense

    MAMMALIAN ASSEMBLAGE STRUCTURE AND HOST-USE PATTERNS OF I. SCAPULARIS ACROSS ANTHROPOGENIC DISTURBANCES IN EAST TEXAS


    Name:  Bradford J. Westrich 


    Major Advisor:  Dr. Iván Castro-Arellano – Texas State University

     

    Committee Member:    Dr. Maria Esteve-Gassent – Texas A&M University

                                          Dr. Thomas R. Simpson – Texas State University

     

    Tuesday, July 11, 2017, 2:00 pm, Supple 153


     

     Borrelia burgdorferi, the causative agent of Lyme disease, is responsible for infecting more than 30,000 people annually in the United States (US), with 95% of cases reported in the Northeastern US. However, human risk for contracting Lyme disease in Texas is much lower, with only 54 cases reported in 2015. Understanding the composition of mammalian reservoir host assemblages is commonly used to predict areas of greatest concern for human risk of Lyme disease. Community dynamic factors such as predation and competition greatly influence the composition of hosts present at any given time; however, anthropogenically-disturbed habitats are positively correlated to increased densities of highly competent B. burgdorferi reservoirs and vectors. My research objectives were to 1) assess if mammal assemblages differed across habitat disturbances; 2) determine if tick intensities were greater in disturbed habitats; 3) assess host-use patterns of tick vectors across East Texas; and 4) identify whether known vectors are associated with competent reservoirs of B. burgdorferi.  I found that mammalian assemblages share high degrees of richness and evenness (Hurlberts PIE = 0.77 – 0.84), although disturbed habitats have greater proportions of rare species comprising 26 – 39% of assemblages. Average individual tick intensity differed across ecoregions in sylvan habitats with 634 ticks collected from mammals at Gus Engeling Wildlife Management Area (GEWMA) and 159 ticks collected from mammals at Big Thicket National Preserve (BTNP). I suspect this difference to be the result of a 13% increase in meso mammal species with greater tick intensities captured at GEWMA. Furthermore, host-use patterns were observed for all Ixodes scapularis adults utilizing meso mammal hosts and approximately 99% of Dermacentor variabilis nymphs selecting small mammal hosts. These results indicate that across evenly distributed mammalian assemblages in East Texas the prevalence of B. burgdorferi is expected to be low due to the rarity of competent reservoirs and association of known vectors with poor tick hosts.

     


    Bio:  Bradford J. Westrich received his B.S. in conservation ecology (2010) from New Mexico State University where he was first introduced to mammal sampling. He then went on to study scarlet macaws in Central America before monitoring threatened and endangered species with the Utah Department of Natural Resources. Prior to joining the Master’s program at Texas State he captained a fleet of airboats charged with monitoring endangered raptors in Florida.


    Thesis Defense

    SPRINGSHED DELINEATION AT CAVE WITHOUT A NAME, TX:

    DYE TRACING IN THE LOWER GLEN ROSE LIMESTONE


    Mark D. Hiler


    Major Advisor: Benjamin F. Schwartz              

    Committee Member: Weston H. Nowlin and Thom B. Hardy   

     

    Thursday, July 6, 1:00 pm, Freeman Aquatic Building 130


    Cave Without a Name (CWAN) in Kendall County, TX contains ~5.5 km of active stream conduits formed in the karstic Lower Glen Rose Limestone which forms part of the Trinity Aquifer System. The primarily rural Kendall County lies just northwest of San Antonio in the Texas Hill Country. The Trinity Aquifer is the primary source of freshwater for this and many other Hill Country counties, although its yields are relatively low compared to the adjacent Edwards Aquifer.

    Springsheds contribute water via recharge features to a spring and are similar to watersheds, except that their boundaries are not constrained by topography. To delineate a springshed for Cave Without a Name, dye tracing was performed by injecting dyes into recharge features in the land surface. Dye tracing utilizes conservative tracers (non-toxic dyes) to trace recharging waters from direct recharge sites to a point of discharge (e.g., springs). For this project, multiple traces were performed from direct recharge sites (sinkholes and/or caves). Regional flow near CWAN is to the Southeast while local flow is towards springs and streams. The Guadalupe River, Spring Creek, and Sabinas Creek are assumed to act as local discharge boundaries, along which a number of known springs occur. Prior work by Veni (1994) and this work suggests that there may be several adjacent springsheds in the area, which is near a large oxbow in the Guadalupe River, just upstream from the confluence with Spring Creek.

    Results showed groundwater flow velocities in the area ranging from high velocity flow (~0.36 km/day) through preferential flowpaths to diffuse flow through the epikarst with low velocity flow (~0.02 km/day). Type of recharge feature, injection method, and hydrologic conditions were found to play significant roles in the behavior of each dye trace. Results may help with future efforts to manage water quality in the area.


     Bio:  Mark Hiler graduated magna cum laude with a B.S. in Geography from Texas State University in San Marcos, Texas.  Before going back to graduate school, Mark joined the Student Conservation Association and participated in two internships with the National Park Service’s Inventory & Monitoring Program where he collected hydrologic data in West Texas, New Mexico, and Arizona. Currently, he is looking for various water resource jobs to join the professional sector of work.


    Thesis Defense

     

    COMPARISON OF FINE SCALE VEGETATIVE PARAMETERS AT ACTIVE AND INACTIVE GULF COAST KANGAROO RAT BURROW SITES

     


    Name: Meagan Marie Bell    


    Major Advisor: Dr. Thomas R. Simpson            

    Committee Members: Dr. Joseph Veech

    Dr. Todd Swannack

     

    Wednesday, June 28, 2017, 9:00 AM, Supple 153


    The Texas endemic Gulf Coast kangaroo rat (Dipodomys compactus) is listed as vulnerable on Texas Parks and Wildlife Conservation Action Plan; however, few ecological studies have focused on Gulf Coast kangaroo rats.  From April 2016 to March 2017, I have seasonally monitored burrowing activity of Gulf Coast kangaroo rats and recorded vegetative parameters at 63 randomly selected sites on a working cattle and wildlife ranch located in Guadalupe County, Texas. Sites with active burrows or a history of occupancy were monitored monthly. Within a 10-m radius plot at each site and using the Daubenmire frame cover estimate technique, I recorded percent cover of the following cover classes: bare ground, standing dead vegetation, litter, living grass, and living forbs. Additionally, I identified to the lowest taxonomic level the dominant live green grass and forb species in each Daubenmire frame and recorded the height of the tallest live grass, live forb, and standing dead vegetation. Using a spherical densitometer, I determined the percent woody canopy coverage at each Daubenmire frame. Twenty-two of 63 sites were occupied. Using Nested ANOVA, I found significantly greater cover of litter, taller standing dead, and taller grass (p < 0.001) at unoccupied sites, while percent cover of forbs, percent cover of bare ground, and distance to the nearest woody canopy was significantly greater (p < 0.001) at occupied sites. Using AICc model selection, the favored logistic model to predict the probability of site occupancy was positively influenced by percent bare ground and forb coverage. Percent woody canopy cover, litter, and grass negatively affected this probability of Gulf Coast kangaroo rat occupancy. This model can aid with future efforts to determine areas to protect Gulf Coast kangaroo rats or other similar species. Comparing the dominant plants at occupied and unoccupied sites, I found greater percentages of plantain (Plantago spp.), rosette grass (Dichanthelium spp.), paspalum (Paspalum spp.), sand bur (Cenchrus spinifex), and hogwort (Croton capitatus) at occupied sites. Except for plantain, these large seeded species are known colonizers of disturbed habitats and which may offer rich food sources. Together, these results suggest Gulf Coast kangaroo rats select for open disturbed areas that can support plants that produce relatively large seeds that are easily extracted from sandy soils.  


     Bio:  Meagan Bell received her B.A. from the University of Texas at San Antonio in Biology with a concentration in Ecology. Working underneath a graduate student at Bent Creek Experimental Forest in North Carolina, she worked as a field technician, looking the impacts of silviculture treatments on small mammals and herpetofauna communities. Since then she has volunteered at Texas Parks and Wildlife in her free time working on both natural resource projects and interpretation programs. She is looking forward to exploring the natural world with her new found freedom and her soon-to-be husband. Currently, she is looking for various wildlife biologist jobs to join the professional sector of work. 


    Thesis Defense

    Rapid quantitative assessment to assist in identification

    of imperiled fishes


    Name: Nicky M. Hahn


    Major Advisor: Dr. Timothy H. Bonner              

    Committee Member:   Dr. Clay Green

                                        Dr. Mar Huertas

     

    Monday, June 26, 2017, 2:00pm, FAB 130


    Methodologies for ranking conservation status of fishes range from a rapid qualitative method (e.g., expert opinion) commonly used by state agencies to time-consuming quantitative method (i.e., Species Status Assessment; SSA) currently used by US Fish and Wildlife Service.  Purpose of this study was to develop a rapid but quantitative methodology for ranking conservation status of freshwater fishes.  Using parameters of SSA, redundancy (i.e., occurrence in numbers of independent drainages and semi-independent reaches, occurrences outside of the study area), representation (i.e., commonality within reaches), and resiliency (i.e., number of reaches with recently reported absences) were compiled for 50 species of fishes within the Edwards Plateau, Chihuahuan Desert, and South Texas Plains ecoregions of Texas.  The 50 species represented 12 families of fishes and consisted of narrowly distributed fishes (i.e., occurring in one drainage) and widely-distributed fishes (i.e., occurring in up to six drainages) and among 1 to 50 reaches.  Twenty-six percent (N = 13) of the fishes occur only within the study area.  Parameters were analyzed with multivariate analysis. Principal component axis I described a redundancy gradient, contrasting narrowly distributed fishes from widely distributed fishes, and principal component axis II described resiliency and representation gradient, contrasting fishes with greater percent absence or percent rare from those with fewer percent absences and occasional to abundant in relative abundances.  Weighted summation of species scores for axes I and II were sorted from least (i.e., towards low redundancy, representation, and resiliency) to greatest (i.e., towards high redundancy, representation, and resiliency), and species were ranked.  Species ranks were similar to the list of Texas Species of Greatest Conservation (SGCN), which were developed from rapid qualitative method, but discrepancies highlighted limitations of qualitative methods and expert opinion.  Most notably, charismatic and well-studied fishes with moderate redundancy, representation, and resiliency were listed as SGCN, whereas less known fishes with lower redundancy, representation, and resiliency were not listed as SGCN.  Among life history traits, top 50% ranked fishes were small-bodied fishes associated with aquifer dependent surface waters.  Reproductive and trophic guilds were similar between the top and bottom 50% ranked fishes.  


    Bio:  Nicky Hahn, originally from Vicksburg, MS, graduated from Louisiana Tech University with a Bachelor of Science in Environmental Science in 2015.  She fell in love with the fish world while working for the Fish Team at the USACE Engineer Research and Development Center during summers and holidays since 2010.  She started the Aquatic Resource Master’s program in 2015 and has enjoyed being part of ‘Minnow U’ and the Bonner crew ever since.  After graduation, Nicky hopes to pursue a doctorate in fish ecology and explore the world with her soon-to-be husband.


    Thesis Defense


    CHANGES IN LEAF AREA AND NUTRIENT CONTENT OF CELTIS SPP. ACROSS A PRECIPITATION GRADIENT IN TEXAS


    Name: Allison Bordini          


    Major Co-Advisors: Dr. Michael Huston and Dr. Susan Schwinning            

    Committee Member: Dr. David Lemke

    Thursday, June 15, 2017, 9:00 AM, Supple 153


    Precipitation affects plant nutrient quality and ecosystem dynamics both directly and indirectly. Nitrogen is a key nutrient for cell and protein function for both plants and herbivores, and the ratio of carbon to nitrogen is a good indicator of nutrient availability within an ecosystem. Studies have shown that an increase in precipitation increases plant biomass and the C/N ratio, decreasing the plants’ Nitrogen concentration. Using the precipitation gradient occurring across Texas, I wanted to find if leaf quantity increases while leaf nutritional quality (using C/N) decreases with higher rainfall. I also wanted to determine if soil mineral nutrients showed a unimodal relationship, with mineral dissolution and leaching increasing with precipitation. For my study, I sampled three species of Celtis spps. (Family: Cannabaceae) across the longitudinal, precipitation gradient of Texas and measured their area and specific leaf area (SLA) to determine a change in leaf size and C/N using the Flash EA 1112 C/N Analyzer to study leaf nutritional quality. I also collected soil samples at each sampling site, dried and ground the soils, and used a Mehlich-3 analysis to determine relative concentrations of soil mineral nutrients at leach sample site. Of the three species, Celtis reticulata was the only one that showed any statistically significant patterns, and regression analysis showed an increase in size and C/N ratio as precipitation increased. While not significant, I also found a general decrease in soil P, Na, K, Mg, Ca, and Mn with increased rainfall, and an increase in the more toxic soil Fe, Cu, Zn, and Al. The higher concentrations of these elements may contribute to a decrease in plant nutritional quality. My results for C. reticulata showed high variability between all samples, but I conclude that in general, leaf quantity (area, SLA) increased while the leaf nutritional quality decreased with precipitation. The decrease in nutritional quality may be due to the dilution of leaf nitrogen as leaf size increases and the increase in more toxic soil nutrients as beneficial nutrients are leached from soils.      


     Bio:  Allison Bordini received her B.A. from Austin College in Sherman, TX in Environmental Studies with a minor in French and Biology. She studied the health of the endangered Littoral Forest in Madagascar using chameleons as an indicator species (2012), and has a strong background in environmental education. When she’s not studying biology or educating the future, Ms. Bordini is usually with her precious dog, Colette. She is also an avid baker and thoroughly enjoys exercise.


    Dissertation Defense


    ECOLOGICAL FACTORS OF RODENT ASSEMBLAGE STRUCTURE AFFECTING HANTAVIRUS PREVALENCE AT VARYING SPATIAL SCALES

     


    Name:  Matthew T. Milholland


    Major Advisor:  Dr. Iván Castro-Arellano – Texas State University                       

    Committee Members:  Dr. Joe Veech – Texas State University

                                         Dr. Rodney Rohde – Texas State University

                                         Dr. Tom Lee – Abilene Christian University

                                         Dr. Gerardo Suzán – Universidad Nacional Autónoma de México

     

    Monday, 05 June 2017, 9:00 am SUPP-153

     


    Zoonotic pathogens are the dominant cause of novel and reemerging infectious diseases. Hantaviruses (family Bunyaviridae) and their associated human diseases occur globally and differ according to their geographic distribution and type of illness exhibited in humans. Prevention of these diseases requires surveillance of seroprevalence in animal populations. Small mammal assemblage structure and species richness are suggested as strong drivers for the maintenance and spread of hantavirus infections. Climatic factors, such as precipitation, can influence reservoir density and abundance by increasing available food resources. These fluctuations in rodent assemblage structure can contribute to the maintenance or reduction of hantavirus seroprevalence. My research objectives were to: 1) determine the ecological correlates of hantavirus prevalence in small mammal assemblages at the site, region, continent, and global levels; 2) to compare differences in prevalence found in sylvan and disturbed habitats; 3) investigate the relationship between phylogenetic diversity and prevalence; 4) develop predictive models for hantavirus prevalence in rodent assemblages using defined ecological correlates; and 5) to quantify transmission events and seroconversions between naïve and infected rodents. I found that of the currently recognized 681 Cricetid, 730 Murid, 61 Nesomyid, and 278 Sciurid species, approximately than 11.3%, 2.1%, 1.6%, and 1.1% respectively, have known associations with hantaviruses. The diversity of hantaviruses hosted by rodents and their distribution among host species supports a reassessment of the paradigm that each virus is associated with a single host species. By considering reservoir host diversity and distribution patterns I holistically evaluate the symbiotic and pathogen-host associations between rodents and hantaviruses. I examine this association on a global taxonomic and geographical scale, model these associations, compare habitats (i.e. sylvan vs. peridomestic) across a latitudinal gradient from Texas through México with emphasis placed on the rodent host diversity and distribution, and quantify infection seroconversion rates of naïve, wild rodents from interactions with naturally infected conspecifics.


    Bio: Matthew T. Milholland received his B.S. in biology (1996) from Abilene Christian University and studied physiology at UNT Health Science Center at Fort Worth before obtaining his M.S. in wildlife ecology from Texas State University in 2005. He has been a contract biologist throughout Texas and an adjunct instructor at Cisco College before beginning the Ph.D. Aquatic Resources program at Texas State in January 2013.  He and his wife of 21 years, Megan, have two children, Noah (12) and Posey (8), of whom he is extremely proud.


    Thesis Defense


    Examining Genetic Variation and the History of Differentiation in the Pallid Dotted-Blue Butterfly (Euphilotes pallescens) Within the Great Basin

     

     


     

     

    Name Sarah B. Bialik


    Major Advisor: Dr. Chris Nice         

    Committee Members: Dr. Noland Martin and Dr. David Rodriguez

    Wednesday, May 31st, 2017, 10:00 AM, Supple Science Building 153


    Quantifying genomic variation provides information that can be used to understand the evolutionary history of populations. In this study, I focused on populations of Euphilotes pallescens, a species of butterfly that lives within the Great Basin of North America. I genotyped 376 butterflies at over 90,000 loci to address two major questions: 1. Has gene exchange occurred among lineages of E. pallescens or between E. pallescens and other geographically proximate Euphilotes species? and 2. If there is evidence of admixture, what are the relative contributions of historical and contemporary gene exchange in the history of these butterflies? I stratified loci into “common” and “rare” loci based on minor allele frequencies to investigate historical and contemporary genetic structure, respectively. I used a Bayesian hierarchical model to visualize and quantify genetic variation in two analyses: one included just E. pallescens lineages, while the second analysis was performed at the genus level. I found evidence of both historical and contemporary gene exchange among subspecies within E. pallescens and among Euphilotes species. However, there was little evidence of a history of admixture between the Great Basin populations of E. pallescens and other Euphilotes species. I also found conflict between the patterns of genomic differentiation in these butterflies and their nominal taxonomy. My investigation of the evolutionary history of these butterflies revealed complex relationships and patterns of gene exchange between lineages that suggest the organization of biological diversity is not always strictly hierarchical and the history of divergence is not always strictly bifurcating.


    Sarah Bialik was raised on a farm in Williamstown, Kentucky. She attended Centre College in Danville, Kentucky where she did population genetics research on sea squirts and earned her B.S. in Biology and Environmental Studies in 2015. Sarah realized she loved doing research and joined the Nice Lab in 2015 to work on these wonderful butterflies and earn her M.S. in Population and Conservation Genetics. She enjoys baking, knitting, yoga, rock climbing and playing with her puppy, Telo. She will be moving up to Austin with her soon-to-be husband and plans to pursue a career in research.


    Thesis Defense

    POPULATION GENETICS OF A FUNGAL AMPHIBIAN PATHOGEN IN CENTRAL TEXAS


    Thomas L. Marshall


    Major Advisor: Dr. David Rodriguez      

    Committee Member: Dr. Michael R. J. Forstner and Dr. Dittmar Hahn

    Thursday, May 25, 2017, 9:00 AM, Supple Science Building 112


     Chytridiomycosis, an emerging infectious disease caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is a major contributor to declines in amphibian populations worldwide. Bd was first described in the 1990s, and there is still much to learn about its regional diversity and origin. The Global Panzootic Lineage (Bd-GPL) has been responsible for devastating amphibian population declines and extinctions in Central and South America, Australia, and the western US. On the other hand, a few localized endemic lineages have been discovered in regions such as Brazil and Asia, which have not experienced such severe disease outbreaks. There are still several geographic sampling gaps in the global genetics of Bd, and relatively few studies have focused on regions in which Bd exhibits low virulence, thus creating a bias in our current knowledge of the pathogen’s diversity. One such region that has not seen disease-associated declines is the state of Texas. This pathogen has been detected from amphibians in the state, although strains had not been characterized genetically prior to this study. Here, I isolated, cultured, and genotyped strains of Bd in Central Texas and compared them to a panel of previously genotyped strains distributed across the globe. My results support the hypothesis that Bd is an introduced pathogen in the region. I found a diversity of Bd genotypes yet did not detect genetic structure in Texas and across North America. Strains in Central Texas are genetically similar to those in the western U.S. that have caused amphibian population declines, which raises questions about the roles that climate and host resistance play in shaping Bd-amphibian disease dynamics in the region.

     


     Bio:  Thomas Marshall was born in Princeton, NJ and raised in Dallas, TX. He graduated with a B.A. in psychology from Vanderbilt University in 2003 and soon after relocated to Austin, TX where he spent his free time chasing after reptiles and amphibians along the Barton Creek Greenbelt. He returned to school to study biology at Texas State University as a post-grad and then joined the Rodriguez lab as a Master’s student in the fall of 2015. He will begin his doctoral program this fall in the David Hillis lab at University of Texas at Austin and investigate the phylogenomics and evolution of snakes.

     

     


    Dissertation Defense


    "Reevaluating the reproductive ecology of the endangered Houston Toad (Bufo [=Anaxryus] Houstonensis) using automated audio and environmental monitoring techniques"

     


    Andrew MacLaren


    Major Advisor: Michael R. J. Forstner, Department of Biology, Texas State University   

     

    Committee Members: Shawn F. McCracken; Floyd Weckerly, Department of Biology, Texas State University.

    Benjamin M. Bolker, Departments of Biology and Mathematics, McMasters University, Hamilton, Ontario, Canada.

    J. Andrew Royle, United States Geological Survey, Patuxent Wildlife Research Center, Laurel, MD.

     

    Tuesday, May 16, 2017, 1:00 pm, Supple 257


    The Houston Toad (Bufo [=Anaxyrus] houstonensis) is an endangered species of anuran endemic to east central Texas. Many of the assumptions regarding the natural history of the Houston Toad are founded in documents that provide little or no statistical evidence for their conclusions. This dissertation is focused, in part, on testing these observations using data gathered from remote audio recording devices to either substantiate or refute them. These devices are used to capture the sounds of male anurans chorusing at potential breeding locations for Houston Toads. These devices record audio 10 minutes per hour, 12 hours per night, every night between January and July, providing presence/absence data for the Houston Toad and co-occurring species at a rate that is unable to be matched by human observers. In some instances, these data allow for new discoveries to be made that have gone undetected through less rigorous sampling regimes. In other instances, the regularity and long-term provenance of these data require several currently held paradigms concerning the chorusing behavior of the Houston Toad to be challenged or re-evaluated. Given that auditory cues alone inform regulatory policy and enforcement, improving methods of detection inherently have the greatest impact on the conservation of this species. I intend to use these data to re-characterize the call of the Houston Toad, which is often misrepresented in textbooks and field guides; to describe the climatic conditions correlated with chorusing, the annual variation in chorusing phenology, and determine whether forecasted long-term climate change will impact favorable chorusing (i.e. breeding) conditions; to investigate the interaction between chorusing Houston Toads and Coastal Plains Toads (Bufo [=Incilius] nebulifer); and finally, to utilize these data to determine whether currently in place protocols for acoustically monitoring this species are adequate, and improve them if possible. 


    Bio: Andrew comes from Northwest Houston (near where the Houston Toad was first described) where he graduated from Langham Creek High School, then attended Lone Star College. He then completed his bachelors in biology at Texas State University in Fall 2013. He then completed his Masters in August 2015 focused on the development of audio recognition tools for the Houston Toad. He has two guinea pigs whose names are Einstein and Newton.


    Thesis Defense

     

    SPECIFICITY OF TLS11a APTAMER TOWARDS HEPATOCELLULAR CARCINOMA AS A MEANS OF DETECTION AND TARGETED DRUG DELIVERY


    Name: Katie A. Kendrick

                                                                                             
    Major Advisor:  Dr. Shannon Weigum            

    Committee Members:  Dr. Dana Garcia and Dr. Joe Koke

     

    Tuesday, May 9,2017,  8:30 am, Supple 257


    Liver cancer is the sixth most common occurring cancer and second leading cause of cancer-related deaths worldwide. An estimated 75% of all liver malignancy cases are hepatocellular carcinoma (HCC), the most common and most lethal form of liver cancer. While the incidence rates for many cancers have slowly declined over the years, HCC incidence and death rates have continuously risen due to poor prognosis and late stage diagnoses. This suggests that there is a lack of existing biomarkers and diagnostic equipment sensitive enough to identify this disease and that more sophisticated methods are needed to specifically target HCC and detect it at its early stages. Recently, an HCC-specific aptamer was described and shown to effectively discriminate mouse HCC from normal liver in vitro. In this thesis, the specificity of TLS11a towards human HCC is addressed. Specifically, immunohistochemistry staining of human tissue microarrays (TMAs) were utilized to address what tissue types TLS11a can bind, if it can differentiate between normal liver and HCC and if binding is coorleated with tumor grade. Staining of fresh frozen TMAs showed TLS11a could distinguish between human normal liver and HCC tissue (p<0.001) with the mean integrated intensity increasing more than an average 10-fold in HCC tissues. TLS11a was also found to bind to HCC tissue with higher affinity than any other malignat tissue type (p<0.001) other than testis (p=0.122), and little to no binding to other normal tissue types (p<0.001). These results signify that TLS11a is highly specific to human HCC tissues and show its ability to recognize its target epitope with high affinity when compared to other tissue types. Although follow up studies are needed to confirm, these findings suggest TLS11a would be an excellent candidate for use in human studies for new HCC-targeted diagnostic and therapeutic applications.


    Katie Kendrick was born and raised in San Marcos, Texas. She graduated from Texas State University with a Bachelor of Science in 2014, and returned to join Dr. Weigum’s lab and earn her MS. After graduation, Katie plans on applying to medical school in the hopes of becoming a physician. Outside of her graduate studies, Katie enjoys being a mom and spending time with her amazing son and daughter.   

  • Dissertation Proposal Defense


    A consideration into ways biology-based student organizations

    facilitate partition in STEM

     


    Zachary L Nolen


    Major Advisor: Dr. Kristy L Daniel            

    Committee Members: Dr. Carrie Bucklin, Dr. Ivan Castro-Arellano,

    Dr. Eleanor Close, and Dr. Paula Williamson   

     

    April 21, 2017, 10:00 a.m., Norris Room


     

     Abstract. The United States has fallen behind other developed countries in the field of science resulting in fewer students entering scientific careers. It is speculated that students are leaving the field during or immediately following their degree program because students have not developed a strong perceived attachment to the field of science. One way that students may build this perceived attachment to science is through participation in science-based social organizations. The purpose of my study is to investigate the ways and reasons students participate in biology-based student organizations and the relationship between those experiences and students’ perceived attachment. I will recruit three biology-based student organizations (Beta Beta Beta Biological Honor Society, Wildlife Society, and Microbiology club) to identify the extent that they exhibit characteristics of affinity groups. Data sources will include member responses to an open ended questionnaire, field observations, relevant artifacts, and focus groups with student leadership. I will analyze these data to determine the process by which these student organizations plan and execute activities. Additionally, I will explore the relationship between participation in these activities and members’ perceived attachment to their respective organizations and biology. My findings will highlight how student organizations may be shaping the scientific future of students in ways we do not yet understand.


    Bio:  Zach Nolen earned his B.S. in Biology from the University of North Alabama in Florence, Alabama in 2011 and his M.S. in Biology from the University of Alabama in Birmingham in 2014. He began studying under Dr. Kristy Daniel at the University of Southern Mississippi in 2014 before transferring with her to Texas State University where he joined the Aquatic Resources program. Upon completing his doctoral degree, Zach hopes to pursue his passion for teaching at the university level and remain on the cutting edge of science education research.

     


    Thesis Defense

     

     

    “CHARACTERIZING STREAM-AQUIFER INTERACTIONS OF THE PEDERNALES RIVER WATERSHED IN CENTRAL TEXAS”

     

     Raddiete Ghion

    Major Advisor: Dr. Vicente Lopes Raddiete Ghion

    Committee Members: Dr. Alan W Groeger and Mr. Rene Barker

    Monday, April 24, 2017, 11:00 AM, Freeman Aquatic Building 130

     

    Understanding of stream-aquifer interactions is relevant to determining and managing the hydrologic impact

    of river and groundwater usage. Traditional techniques to analyze stream-aquifer interaction are based on

    digital ground-water flow models, however, aquifer parameters for model calibrations are generally

     unavailable and difficult to obtain. Recession curve analysis is an alternative approach to determine stream-aquifer interaction in a watershed. Basic assumptions in recession curve analysis include: no regulation on the stream, stream fully penetrates the aquifer, the watershed is underlined by impermeable rocks, aquifer systems have uniform hydraulic conductivity and transmissivity, aquifer system that sustains stream flow is a one-dimensional system (neglects vertical interaction with deeper aquifers), and watershed has uniform storage and recharge.  This study sought to investigate changes in precipitation, streamflow, baseflow, and hydrologic properties of the Pedernales watershed in central Texas, as well as identify the primary aquifer system

    contributing flow to the Pedernales river from 1940 to 2014. The USGS Ground Water Tool box RECESS program was used to extract recession segments and the slope (K) of each segment (recession curve index, RCI). Man-Kendall Monotonic trend (MK) test was used to assess changes in climatologic and the hydrologic parameters during the study period. Annual trend analysis of precipitation streamflow, baseflow and RCI

    showed no significant changes across the study period. Values of stream-aquifer property T/a2s (where T is the transmissivity of the aquifer, a is the average distance from the river to the watershed dived, and S is the storage coefficient of the aquifer) was estimated as 0.0403 d-1 and the watershed K value was 23.15 days/ log cycle.

     It is concluded that the Hensel formation of the Cretaceous aquifer is the primary source of baseflow in the Pedernales River above the Johnson City gage. Results of this study are relevant to water resources management

    in the study area to satisfy the needs of a growing population while maintaining the ecological integrity of the stream-aquifer system. The approach used in this study can be readily available to other watersheds as it only requires recession and streamflow hydrograph analysis, the assurance that the stream system under consideration

     is not regulated, and that linearity of the recession curve of the watershed is observed.

     

    Bio: Raddiete Ghion obtained a BS in Biology (2014) from Texas State University. Upon graduation she wanted to complete a Master’s degree, she entered the MS Biology program in Fall 2014 and joined Dr. Lopes lab where she became interested in groundwater hydrology. Raddiete aims to pursue a career in environmental planning and integrated watershed management in Austin, TX


    Thesis Defense

    An Investigation of Relationships Between Student Acceptance of Evolution, Tree-Thinking, and Eye Movement among
    different Instructional Interventions


    Name: Austin Leone


    Major Advisor: Dr. Kristy L. Daniel             

    Committee Members:  Dr. Joseph A. Veech, Dr. Julie F. Westerlund  

     

    April 6, 2017, 8:30 AM, Norris Room


    Evolution is the unifying theme for the field of biology and is one of the most well developed and supported scientific theories to date. Although overwhelming evidence exists supporting evolution, evolution is considered a socio-scientific issue. Socio-scientific issues are potentially controversial social issues stemming in science content. For example, climate change, stem cell research and the concept of life are also current socio-scientific issues. Unfortunately, given the potential controversy, a large amount of the public still rejects evolution. In attempt to counter the controversy, educate people, and communicate the scientific basis for evolution, biologists commonly use a diagram called the phylogenetic tree. These diagrams represent hypothesized evolutionary relationships and learning how to accurately interpret and generate phylogenetic trees, called tree-thinking, is a difficult task for learners. Previous studies have investigated the relationship between tree-thinking and evolution acceptance. But, these results were based on an instrument limited in reliability. Additionally, these studies only incorporated a single, integrated instruction method. Using a new instrument which quantitatively measures tree-thinking and a reliable instrument which measures evolution acceptance, I investigated the relationship between tree-thinking learning outcomes and evolution acceptance in 884 undergraduate students from five different instructional interventions. Students completed the instruments both before and after learning about trees for one week of instruction. I found a significant but weak correlation between evolution acceptance and student tree-thinking learning. I also found that in non-majors biology students, evolution acceptance only explains 1.4% of the variance found in learning about tree-thinking. Knowing that students hold numerous misconceptions when interpreting phylogenetic trees, I used eye-tracking technology to investigate how these students visually interacted with these diagrams. I found that students spend the most amount of time looking at the tips of trees that incorporate organisms more than trees that incorporate abstract letters. My findings suggest that evolution acceptance does not significantly explain how students learn about phylogenetic trees. Additionally, biometric data indicates that students do not interact with trees as expected, with visual interactions closely aligned with expectations of common misconceptions.  



     Bio: Austin Leone graduated from the University of Oklahoma in Norman, Oklahoma with a B.S. in Zoology (2014). He began studying under Dr. Kristy Daniel for his M.S. in Biology at Texas State University in Fall 2015, and will continue his education as a Ph.D. student in Oklahoma State University’s Integrative Biology program. After participating in a recent study abroad program to Southeast Asia, Austin hopes to travel and continue learning about how evolution is accepted on a global scale. Ultimately, Austin aims for a career in higher education as a biology education researcher.


    Thesis Defense

     

    EASTERN BLACK RAIL (LATERALLUS JAMAICENSIS JAMAICENSIS) OCCUPANCY AND ABUNDANCE ESTIMATES ALONG THE TEXAS COAST WITH IMPLICATIONSFOR SURVEY PROTOCOLS


    James D. M. Tolliver

                                                                                             
    Major Co-advisors:  Dr. Floyd W. Weckerly and Dr. M. Clay Green           

    Committee Member:  Dr. Joseph A. Veech

     

    Monday, April 3, 2017, 2:30 pm, Supple Science Building 257


    Eastern black rails (Laterallus jamaicensis jamaicensis) are a subspecies of conservation concern.  These birds vocalize infrequently and inhabit dense vegetation making them difficult to detect.  I conducted the first large scale study of black rail occupancy and abundance in Texas.  I repeated point count surveys at 308 points spread across six study sites from mid-March to late-May in 2015 and 2016.  Each survey at a survey point was a 6-minute call broadcast.  My study sites were Anahuac, Brazoria, and San Bernard National Wildlife Refuges, Mad Island Wildlife Management Area, Clive Runnel’s Mad Island Marsh Preserve, and Powderhorn Ranch Preserve.  I estimated 19 occupancy and 19 abundance models that also accounted for imperfect detection.  Black rail detection increased with moon phase and temperature but decreased with wind speed and ambient noise.  Occupancy and abundance increased with herbaceous, woody, Spartina, and intermediate marsh cover.  Black rail occupancy and abundance estimates were similar between years.  From the estimated detection probabilities I determined that ~ 16 surveys could establish absence of the species at survey points.  I reached two main conclusions.  One, black rail management, during the breeding season in Texas, should focus on Spartina cover as occupancy and abundance estimates were highest when Spartina cover was high.  Two, effort to establish black rail absence from naïve occupancy estimates is impractical.  Monitoring efforts of black rails, in Texas, should design studies that estimate distribution and abundance while accounting for imperfect detection. 



    Bio: James Tolliver was born and raised in central Texas.  He became interested in the natural sciences at a young age and decided to pursue a career in the wildlife sciences.  James graduated from Arthur Temple College of Forestry and Agriculture, Stephen F. Austin State University in 2013 with a Bachelor of Science in Forestry and a major in wildlife management.   He took various technician jobs until he was accepted into the M.S. program at Texas State University.  James joined the program in 2015 to work, in Drs. Green’s and Weckerly’s labs, on black rails.      


    Thesis Defense


    Predicting Groundwater Level using Data Mining Techniques: A Case Study of the Edwards Aquifer


    Lenée A. Dedeaux


    Major Co-Advisors: Dr. Benjamin F. Schwartz, Biology, and Dr. Yihong Yuan, Geography

    Committee Member: Dr. Ronald T. Green, Southwest Research Institute

     

    Thursday, March 23, 2017,  2:00 PM , Freeman Aquatic Bldg., room 130

    Continuous groundwater level data collected from observation wells in the Edwards Aquifer provide large time-series datasets useful for predictive modeling of groundwater levels across a wide range of aquifer conditions. However, due to the complex hydrogeology of the Edwards Aquifer, groundwater wells exhibit varying degrees of spatiotemporal dependency and heterogeneity challenging accurate groundwater level predictions. In this study, the data mining techniques of hierarchical clustering, a method to rank data based on response, and artificial neural networks (ANNs) to predict groundwater levels, were applied in a two-step approach with the specific goal of increasing groundwater level prediction accuracy in wells in the Edwards Aquifer. In step-one, a hierarchical clustering analysis was conducted using the time-invariant Distance Time Warping (DTW) algorithm as a measure of similarity to identify groups of wells that exhibit similar responses across a wide range of hydrologic conditions. In step-two, the datasets of the wells that clustered together across all hydrologic conditions, along with precipitation and spring flow datasets, were used to train artificial neural networks (ANNs) to predict daily groundwater levels for each of the other wells in the cluster. The results of this study show that the data mining techniques of hierarchical clustering and artificial neural networks, applied in a two-step approach, can increase groundwater level prediction accuracies. This methodology is useful for predicting missing values in time series datasets, simulation of groundwater levels, and calibrating numeric models.



     Bio: After graduating this spring with a MS in Aquatic Resources, Lenée hopes to research climate change while pursuing her PhD. When not busy being with graduate studies, Lenée is the mom to three wonderful daughters who are future scientists and wife to a very supportive and patient husband.


    DISSERTATION PROPOSAL DEFENSE

    EXAMINATION OF ECOPHYSIOLOGY AND TROPHIC ECOLOGY OF EPIGEAN AND HYPOGEAN INVERTEBRATES FROM EDWARDS AQUIFER


    Name: Parvathi Nair

                                                                                                                                                                                  Major Advisor: Dr. Weston Nowlin, Department of Biology, Texas State University             

    Committee Members: Dr. Benjamin Schwartz, Department of Biology, Texas State University

                                        Dr. Thom Hardy, Department of Biology, Texas State University

                                        Dr. Benjamin Hutchins, Texas Park and Wildlife

                                        Dr. Joe Tomasso, Auburn University

     

    Monday, March 6, 2017, 9:00 am, Freeman Aquatic Building, Room 130


                The Edward Aquifer (EA) in central Texas contains one of the most diverse communities of subterranean and spring-associated organisms in the world, but the ecophysiology and trophic ecology of many of these organisms are poorly understood. Most subterranean ecosystems are characterized by severe resource limitation due to spatiotemporal patchiness of food resources because of lack of autotrophic production and intermittent inputs of surface-generated organic matter (OM). A long-standing hypothesis in subterranean biology posits that organisms living in subsurface habitats can withstand long periods of resource shortages and have increased starvation resistance due to reduced metabolic rate. In the first portion of my dissertation, I will investigate the effects of food deprivation in several related groundwater-, spring-, and surface-associated macroinvertebrates from the EA. It is also thought that organisms living in environmentally stable environments, such as subterranean habitats and at surface springs should exhibit relatively small ranges in thermal and environmental tolerances; however, results from experiments examining this prediction are equivocal.  In the second portion of my dissertation, I will evaluate this hypothesis by investigating responses of spring- and surface-associated macroinvertebrates to increasing water temperatures and decreasing DO concentrations. Lastly, some hypogean-adapted organisms exist in both belowground and in surface spring habitats; these spring openings serve as an ecotone between surface and subterranean environments and both surface and subsurface organisms can occupy this habitat. In spring systems where both subsurface and surface species coexist, it is unclear how these groups of species potentially occupy habitat space and utilize resources in what is thought to be a homogenous and resource poor environment.  I will investigate potential resource and microhabitat partitioning in the invertebrate community located along springs in the Comal Spring system in the EA using stable isotopes. The information obtained through these studies will be beneficial for devising conservation strategies and captive breeding programs for EA invertebrate species and for habitat conservation and restoration measures.



    Bio: Parvathi Nair was born in Kerala, India. She earned a B.S. in Zoology in 2008 and a M.S. in Fisheries Science in 2010 from the University of Mumbai, India. She came to the USA in 2011 and earned a M.S. in Environmental Science in 2013 from University of Houston Clear-Lake, TX. She entered the Aquatic Resources Ph.D. program at Texas State University in 2014, in Dr. Weston Nowlin’s lab, to work on the conservation of endangered invertebrates in the Edward Aquifer.


    Thesis Defense

     

     INTEGRATION OF A LATERAL FLOW IMMUNOASSAY PANEL FOR GASTROENTERITIS WITH SWAB-BASED SAMPLE PREPARATION CARTRIDGE


    Name: Zhenyuan Lu

                                                                                             
    Major Advisor:  Dr. Shannon Weigum            

    Committee Members:  Dr. John C. Carrano and Dr. Rodney Rohde

     

    Thursday, March 2, 2017,  9:00 am, Norris room


    Gastroenteritis is one of the most common and deadly diseases, causing a combination of diarrhea, vomiting, and abdominal pain. In developing countries, there is a lack of advanced medical instruments, well-trained medical personnel and funding to process complex diagnostic tests that inform treatment decisions. Therefore, there is a need to develop inexpensive, easy-to-use, rapid, portable and highly sensitive detection assays that do not require complex testing procedure or highly trained personnel. To address this need, we propose the development of a novel lateral flow immunoassay (LFIA) that uses colorimetric or chemiluminescent signal enhancement of gold nanoparticles (AuNP) that can be integrated with a point-of-care, swab-based sample preparation cartridge, known as the Paratus SDS® Cartridge (Paratus Diagnostics, LLC. Austin, TX). These LFIA devices will be fabricated using a combination of laser cutting and wax printing to create physical or hydrophobic barriers that direct metered volumes of sample fluids extracted from the Paratus SDS® Cartridge onto the LFIA test strip. Capillary action will draw fluids toward the reaction zone where embedded multiplex immunoassay reagents will be embedded in a 3 x 3 microarray spot pattern. If the target pathogen is present, a sandwich based immunoassay complex will form between the capture antibody, pathogen, and detecting antibody, yielding a spatially resolved colorimetric or chemiluminescent signal. Preliminary results using a single pathogen, Norovirus GII.4 virus-like particles (VLPs), yielded visible AuNP signals in the presence of as little as 50 pM VLPs using this integrated sample prep/detection system. Additional optimization and refinement of the LFIA is ongoing and will involve antibody characterization for multiplexed assays and built-in LFIA structures for seamless integration with the Paratus SDS® Cartridge.



    Zhenyuan Lu was born in Shanghai, China and earned his B.E. from Southwest University of Science and Technology, China with a major in Bioengineering. After graduation, he became a gorilla keeper at an animal zoo; and then worked at a cosmetic company as a R&D engineer until he joined Dr. Weigum’s Lab at Texas State University in 2015. Meanwhile, he is a freelanced photographer and owns a photography studio for weddings, portraits, chasing dogs…since 2013.

  • Thesis Defense

    “Optic Nerve of Zebrafish (Danio rerio) as a Model for Aging Studies in Humans”


    Name: Pedro Gonzalez Jr.


    Major Advisor: Dr. Dana M. García

    Committee Members: Dr. Shannon Weigum, Dr. Joseph Koke  

    Monday, November 7, 2016, 3:00 PM, Norris Conference Room


    The optic nerve is the cranial nerve that sends messages from the eyes to the brain and is part of the central nervous system (CNS). Astrocytes help maintain neuronal health within the CNS. In humans, senescence of astrocytes is thought to be a factor in aging related diseases. Astrocytes uniquely express glial fibrillary acidic protein (GFAP), a type of intermediate filament. High levels of expression of GFAP are one indicator of reactive astrocytosis. Since increased expression of GFAP is a characteristic response to injury or disease, we hypothesize that increased expression of GFAP in the optic nerve of zebrafish correlates with aging of zebrafish We also investigated p16-ARC, a protein that has been associated with aging-related diseases. Lastly, studies on the changes in the optic nerve of human cadavers in which measurements of the optic nerve were done revealed that there was an increase in the diameter with increasing age. We performed similar measurements on the optic nerve of the zebrafish. If all three of these indicators for aging and senescence are observed, then zebrafish may be a tenable animal model for understanding aging in humans.

    The fish were raised in aquaria located in Room 272 of the Supple Science Building or purchased from ZIRC to ensure the exact age of the fish. Fish were euthanized, fixed and dissected. The tissue was be frozen, embedded and sectioned into 20 mm thick sections using a cryotome and then adhered to gelatin-coated coverslips. Antibodies for immunolabeling Gfap were anti-GFAP (zrf-1) raised in mouse (1:200 dilution) as the primary antibody and goat anti-mouse Alexa Fluor 488 (1:300 dilution) as the secondary antibody. The same protocol was used for immunolabeling p16-ARC, but with the addition of anti-p16 antibody and the appropriate secondary antibody. Tissue sections were observed and positive and negative control images were acquired using an Olympus FV1000 confocal laser-scanning microscope. Intensity of labeling was quantified by measuring the pixel intensity using ImageJ software. Optic nerve diameters were measured from images obtained from 6 (n = 5), 9 (n = 5) and 12 (n = 3) month old fish.  Outliers were removed. Data were analyzed using ANOVA and post-hoc t-tests. Contrary to expectations, GFAP labeling was observed in zebrafish as young as 3 months old.  Intensity and extent of labeling increased as fish aged.  Labeling of p16-ARC was observed in 9 and 12 month old fish, but not in 3 and 6 month old fish. The diameter of the optic nerve increased significantly as the fish aged. Overall, our study may support zebrafish as a model organism for better understanding aging in humans.



    Bio: Pedro Gonzalez, Jr. obtained a BS in Biology (2014) from St. Mary’s University in San Antonio, Texas. Upon deciding that he wanted to complete a Master’s degree, he entered the MS Biology program in Fall 2014 and joined Dr. García’s lab where he became interested in Neurobiology. Pedro aims to pursue a career in the medical field as a PA and return to his hometown (Harlingen, TX) to serve patients in the underserved region of the Rio Grande Valley.


    Thesis Defense


    “Mechanisms of Escherichia coli and Vibrio cholerae fitness when grown in co-culture”


    Name: Candace Longoria


    Major Advisor: Dr. Robert JC McLean

    Committee Members: Dr. Karl Klose, Dr. Kavita Kakirde  

    Thursday, November 3, 2016, 9:30 AM, Norris Room


    Vibrio cholerae is a gram negative bacillus that possesses a single flagellum and is commonly known to have two toxigenic strains: serogroups O1 and O139; both are causes of epidemics. V. cholerae normally lives in brackish aquatic environments that have varying conditions that include temperature, salinity, and pH. Escherichia coli is normally found in the intestinal tract and E. coli K-12 is a commensal non-virulent strain used in many laboratory settings. E. coli and V. cholerae were observed in planktonic and biofilm mixed cultures and V. cholerae was seen to have a reduced fitness in the biofilm environment. To test which E. coli genes are essential for growth with V. cholerae, we used the E. coli KEIO knockout collection of specific K-12 genes and tested the ability of various knockouts to grow with V. cholerae. Once the initial screening was complete we saw the deletion of peptidase activity, most so with pepA-, had visible changes in fitness and growth in both planktonic and biofilm mixed culture. We also used various pepA- strains and plasmids with altered DNA-binding and peptidase activity and observed the growth in mixed culture over a forty-eight hour period. Based on our data, biofilm mixed culture and the lack of peptidase activity may affect the growth and fitness of both E. coli and V. cholerae



    Bio: Candace Longoria spent two years at the University of North Texas on a FOCUS scholarship before transferring to the University of Texas at Austin and graduating with her BS in Biology with a focus in Evolution, Ecology, and Behavior and a Minor in Chemistry. After a year in the real world, she entered the MS Biology program in the Fall of 2014 in hopes of providing a better future for her dog, Pig


    Thesis Defense


    Range expansion of an exotic Asian snail (Melanoides tuberculata)
    into Central Texas rivers, and the parasitological consequences thereof

    Name: Stephen Harding


    Major Advisor:  David Huffman        

    Committee Members:  David Rodriguez and Jake Jackson (BIO-WEST)

    Wednesday, 11/02/2016, 11:00 a.m., FAB130


    The invasive gastropod Melanoides tuberculata (family: Thiaridae) has been established in Texas since the 1960’s.  After being restricted to thermally stable spring runs for decades, these snails have recently exhibited unprecedented range expansions into the surface-fed Guadalupe and lower San Marcos Rivers in Central Texas.  The mechanisms driving this expansion are not yet understood but parasitic consequences of this phenomenon are such that the invasive Asiatic trematodes Centrocestus formosanus, Haplorchis pumilio, and Philophthalmus gralli are likely to follow their snail hosts into novel habitats from which they were previously excluded.  Morphometric methodologies are utilized to qualitatively and quantitatively partition variation observed within and among Texas snail populations.  Additionally, geometric estimates are used to further partition subtle variation in conch morphology.  Snails exhibiting unique combinations of phenotypic traits were subject to molecular analyses using primers targeting the mitochondrial 16s rRNA gene.  Genetic analyses revealed cryptic variation and diversity within and among Texas snail populations.  Local snail invasions are placed into a global context by establishing phylogenetic relationships with other thiarid snails using 16s rRNA data published in GenBank.  This molecular perspective can now serve as a platform for futures studies investigating habitat & thermal preferenda and further studies of the genetic diversity of local M. tuberculata.



    Bio: Stephen Forrest Harding graduated from Texas State University – San Marcos with a BS in Aquatic Biology in 2014.  He entered the MS Aquatic Resources program under the tutelage of Dr. David Huffman in the spring of 2015.  When he is not in the lab he is usually fishing, but can also be found spending time with his fiancée Hope and their two dogs and three kitties.

     


    Thesis Defense

    Gender Differences in Student Attitudes Towards Science in Secondary Classrooms with Resident Scientists in Texas


    Name: Lisa Maria Hanson


    Major Advisor: Dr. Julie F. Westerlund, Ph.D              

    Committee Members: Dr. Paula Williamson, Ph.D. and Dr. Hong-Gu Kang, Ph.D

    Wednesday, November 2, 2016, 10:30 AM, Norris Conference Room


    The purpose of this two-year study was to examine secondary school students’ attitudes about science in four different categories before and after being with PhD graduate students, resident scientists, in their classrooms every week. The study was based upon a National Science Foundation (NSF) program called Project Flowing Waters, a five-year NSF Graduate STEM Fellows in K-12 Education (GK-12) program. The program funded 26 doctoral students, known as NSF GK-12 fellows, who served as bi-weekly resident scientists in science classrooms in local schools.  A newly developed science attitude survey, My Attitude Toward Science Scale (MATS) was used to survey student [n=1111 students] attitudes (Westerlund & Hillman, 2012).  Student attitudes were surveyed in four categories  (a) the subject of science, (b) the desire to become a scientist, (c) the value of science to the society, and (d) the students’ perceptions of scientists.  Matched pre and post student attitude surveys were obtained.  Seventeen resident scientist/teacher partnerships were analyzed, involving 1111 students, in the 2011/12 and 2012/13 school years using a quantitative design.   A control population of students that did not have resident scientists were surveyed in the 2015/16 school.  Both pre and post  surveys were administered at the beginning and again at the end of the school year. Results indicated significant gender differences in attitude changes in some but not all of the four categories.



    Bio: Lisa Maria Hanson graduated from Southwestern Adventist University with a BS in Biology and Business and a MS in Science Education from Touro College. She served as an Educational Coordinator in New York City where her passion for STEM education emerged to encourage more women and minorities in STEM careers. Currently, she is an Anatomy and Physiology Instructor at Coastal Bend Community College. Her passion is to establish a STEM summer camp organization in her home country of Jamaica that will encourage young girls to pursue STEM careers.


    Thesis Defense


    MOVEMENT BEHAVIOR OF UNIONID MUSSELS IN CENTRAL TEXAS


    Name: Bianca Alexandra Hernández


    Major Advisor: Astrid N. Schwalb, Ph.D              

    Committee Members: Dr. Thomas B. Hardy, Clint Robertson, and Dr. David Rodriguez   

    Tuesday, November 1, 2016, 9:00 AM, FAB Conference Room 130


     

    Freshwater mussels are one of the most imperiled groups of aquatic organisms. Burrowing and horizontal movement of freshwater mussels are behaviors integral to their ecology, yet mussel behavior is still relatively understudied. Thus, more insight into mussel behavior is needed to establish effective survey protocols and to inform the development of long-term conservation strategies. My objectives were to 1) examine and compare burrowing depth in the field among species and sites in the Guadalupe and San Antonio Rivers; 2) examine the effect of (a) differences in species, (b) decreases in temperature and (c) different substrates on burrowing behavior in experimental studies; and 3) examine the effect of dewatering on movement behavior.

    Seasonal differences were found at two sites in the San Marcos and Guadalupe River, with more mussels burrowing deeper in winter. In contrast, this was not observed at a predominately sandy site in the San Antonio River, where mussels were burrowed significantly deeper compared to the other gravel/cobble dominated sites, independent of season. Lab experiments showed that differences in substrate affected burrowing behavior, and mussels responded to temperature changes. Burrowing depth was significantly deeper in sand compared to gravel. Further, when temperature was decreased from above 20°C to 15°C, 9% of the mussels stopped burrowing in sand but 58% stopped in gravel. Significant differences between species were only found in lab experiments with sand, in which Amblema plicata burrowed significantly deeper than Quadrula aurea.

    Horizontal movement rates differed significantly when comparing dewatering rates. At the fastest dewatering rate, 100% of the mussels became stranded, whereas 20 to 30% became stranded during slow and moderate dewatering rates. Thus, mussels in Central Texas may not have the ability to respond fast enough when water levels change rapidly, e.g., due to operations of dams. Our results also suggest that surveys may need to follow different guidelines depending on local conditions.


    Bio: Bianca Alexandra Hernández graduated from St. Edward’s University with a BA in International Relations in 2008. She interned for Congressman Lloyd Doggett, Austin and taught abroad in Andalucía, Spain before entering the MS Aquatic Resources program (Schwalb Stream Ecology Lab) in the Spring of 2015. She is a proud dog-mother of two: Bruce and Boris. 


    Thesis Defense

     

    FISH COMMUNITY AND HABITAT ASSESSMENTS

    WITHIN AN URBANIZED SPRING COMPLEX

     OF THE EDWARDS PLATEAU


    Name: Cory Scanes


    Major Advisor:  Dr. Timothy Bonner            

    Committee Members:   Dr. Caitlin Gabor and Dr. Kenneth Ostrand

    Friday, November 4, 2016; 10:30 am. FAB 104


     Abstract: Spring complexes within the arid region of the Edwards Plateau are diversity hotspots and evolutionary refugia for numerous aquatic fauna.  Within the last 100 years, anthropogenic modifications and uses of spring complexes are associated with imperilment of aquatic fauna.  Purposes of this study were to quantify current community structure and habitat associations and to assess biotic integrity of the fish community within the Comal springs complex, the greatest discharge spring within the Edwards Plateau region of central Texas and located within the urban landscape.  Fishes and habitats were quantified among wadeable and non-wadeable areas and among six reaches of the Comal springs complex seasonally for one year.  Twenty-five species and 23,318 fishes were observed. Spring-associated fish richness was six, comprising 77% of the total catch per unit area.  Compared to reference conditions and to historical records, species occurrences and relative abundances suggest that the Comal spring complex has high biotic integrity despite extremely low flow conditions and rotenone treatment in the 1950s and habitat modifications (e.g., low head dams, land use conversion, bank stabilization) and high recreation use since the 1950s.  However, the fish community was not homogenous among all reaches.  Within two reaches of high recreational use (i.e., New Channel and Lower River), spring-associated fish richness and relative abundances were lower than other four reaches but still maintained high relative abundances of the federally-listed Fountain Darter.  Fish-habitat associations were similar to reported habitat associations for most fishes.  A notable exception was observed for the Fountain Darter, which had a more ubiquitous distribution and was not strongly associated with vegetation. Into the future, observations quantified in this study can be used as a baseline to monitor and assess threats to the Comal spring complex.



    Bio:  Cory Scanes graduated from Texas State University with a BS in Biology in 2014.  He entered the MS Aquatic Resources program in the Fall of 2014 studying community ecology of fishes under Dr. Timothy Bonner.  He is currently a senior research associate at the Environmental Institute of Houston at the University of Houston-Clear Lake.


    Thesis Defense

    Dispersal of Zebra Mussels, Dreissena polymorpha,

    Downstream of an Invaded Reservoir


    Name: Jenae Olson


    Major Advisor: Dr. Astrid N. Schwalb                  

    Committee Members: Dr. Todd Swannack, Dr. Robert McMahon, Dr. Weston H. Nowlin

    Friday, November 4, 2016; 9:30 am. FAB Conference Room 130


    Abstract: Zebra mussels recently invaded Central Texas and more information is needed to predict their spread in this region and inform management decisions. Therefore, I examined riverine zebra mussel dispersal, settlement, and growth downstream of Lake Belton, TX, invaded by zebra mussels in 2013. Veliger samples and settlement of juveniles on artificial substrate was monitored at a site in the lake and six sites in the Leon and Little Rivers, 0.4 to 54.7 river kilometers (rkm) downstream of the lake outlet. Veliger declined downstream from highest concentrations from sites closest to the lake outlet (0.4 and 2.5 rkm) and were found up to 13 rkm downstream. This decline was represented best with a logarithmic decline in May, Aug, Oct 2015 (R2 = 0.75 to 0.94), and with an inverse power relationship in June and September 2015 (R2 = 0.53 to 0.73). No clear pattern was found in April 2016 (R2=0.32, p = 0.06). In contrast, maximum juvenile settlement (437 ± 75 m-2) occurred 2.5 rkm downstream in August 2016, but not immediately downstream of the lake. Differences in settlement rates between sites could not be explained by differences in physico-chemical parameters such as temperature or turbidity as they did not differ significantly between sites. No mussels were found at 27 and 55 rkm downstream on artificial or natural substrata between May through December of 2015, but juvenile mussels were found there in April 2016. This suggests that zebra mussels were dispersal limited in 2015, and were able to disperse farther in 2016 probably facilitated by high discharge.



    Bio:  Jenae Olson graduated from Minnesota State University, Moorhead with a BS in Biology with an Emphasis in Ecology in May, 2014.  She entered the MS Aquatic Resources program in the Spring of 2015 and joined the Schwalb Stream Ecology lab to work on mussel dispersal. Her interest include aquatic ecology/ecosystems and outreach programs.

     


    Thesis Defense


    HABITAT AVAILABILITY ASSESSMENT FOR THE GULF COAST KANGAROO RAT (DIPODOMYS COMPACTUS) IN SOUTH-CENTRAL TEXAS


    Laura M. Bliss


    Major Advisor: Dr. Joseph Veech              

    Committee Members:  Dr. Thomas R. Simpson, Dr. Ivan Castro-Arellano

    Monday, October 10, 10 AM, Supple 257


    As the human population increases worldwide, urbanization, habitat destruction, and habitat modification also increase. Recently the urbanization rate in Central Texas has become one of the highest in the nation. The consequential loss of natural habitat could jeopardize native wildlife species that are already somewhat limited in their distribution. Based on specialized life-history traits that limit large-scale mobility, kangaroo rats (Dipodomys spp.) have been found to be especially sensitive to urbanization-induced habitat modification and fragmentation. Dipodomys compactus is one of five kangaroo rat species found in Texas; this species has narrow, specific habitat requirements. Using a geographic information system (GIS)-based habitat suitability model, I determined that due to isolation among suitable habitat patches, actual D. compactus range in south-central Texas is highly fragmented, and the particular population in south-central Texas may be more isolated than currently thought. The assessment strategy of GIS habitat mapping can be broadly applied to other vulnerable species with similarly narrow habitat parameters to predict current and future management requirements.



     Laura Bliss was born in Houston, Texas and earned an Ecology and Evolutionary Biology B.Sc. and a Chemistry B.A. from the University of California, Santa Cruz in August 2010. Upon graduation, she worked as an ESL teacher in Beijing, China for three years. In the fall of 2013, Laura returned to the United States to complete a seabird research apprenticeship program at Friday Harbor Labs, Washington. Laura entered the Wildlife Ecology M.Sc. program at Texas State University in Fall 2014 and began working with Dr. Joseph Veech. Presently, she works concurrently as a NOAA NWFSC Hammond Research Station Fisheries Biologist and the Outreach Coordinator for a student sustainability organization at the University of Texas at Austin. She and her husband, David Dickey, have a 19-year-old cat of whom they are very proud.


    Dissertation Proposal Defense

     

    Plant effects on the dynamics of Frankia populations in soil

     


    Seifeddine Ben Tekaya

    Major Advisor: Dittmar Hahn

    Committee Members: David Rodriguez, Robert McLean, Jeffrey O. Dawson (UIUC), Mark Paschke (CSU)

    Friday, October 7, 2016, 9:00am, Supple 257


    Frankiae are slow growing actinobacteria that are able to form root nodules with some woody non-leguminous plants. Studies on the ecology of these bacteria are hampered by difficulties to isolate them into pure cultures which was a prerequisite for quantitative analyses in the past. We have therefore focused on the development of molecular approaches that allow us to retrieve quantitative data from environmental samples unbiased by the limitations of culturability. A first objective of the current study was to develop qPCR based methods to distinguish groups within the genus and quantify their populations in soil. Additional attempts were made to distinguish and quantify typical, nitrogen-fixing frankiae from atypical, generally non-nitrogen fixing frankiae. Both SybrGreen- and Taqman-based qPCR methods were subsequently evaluated for the quantification of these populations in different soils. These methods are then used to study long term effects of agricultural management practices on abundance and diversity of frankiae. Data from these analyses are contrasted with Illumina sequencing data. Both qPCR and Illumina sequencing methods are also applied in analyses of microcosm experiments aiming to investigate the effects of plants species on indigenous and introduced populations of Frankia and relate abundance/diversity to root nodule populations.



    Bio: Seif was born in Carthage, Tunisia, in May 13th, 1984. He completed a BS degree in Biological Sciences at the University of Tunis el Manar in 2007, and earned an MS degree in microbiology from the same university with a research thesis that focused on the diversity of ascomycetes in high saline lakes in 2009. In 2014, he joined the PhD program in Aquatic Resources at Texas State University.


    Thesis Defense

    SEASONAL AND LONGITUDINAL INVESTIGATION ON THE IMPACTS OF RECREATIONAL ACTIVITIES ON AQUATIC MACROINVERTEBRATES COMMUNITY WITHIN THE SAN MARCOS RIVER


    Name: Ovie Agare


    Major Advisor:  Dr. Thom Hardy                 

    Committee Members:   Dr. Weston Nowlin and Dr. Benjamin Schwartz

    Thursday, October 13, 2016; 8:00 am. FAB Conference Room 130


     Abstract: In the San Marcos River, recreational activities are most pronounced between April and October. Given the continued urbanization and increasing population in San Marcos there is need for a quantitative study on the possible effect of elevated recreational activities on the aquatic macroinvertebrates within the river. Currently, no study has quantified both patterns in macroinvertebrate drift and benthic community structure simultaneously in the San Marcos River.  Information on drift patterns and benthic macroinvertebrate habitat relationships is necessary to understand mechanisms for species persistence within the San Marcos River.  In this study, I examined the seasonal and longitudinal patterns of benthic macroinvertebrate community composition at three different sites within the San Marcos River. I also examined the seasonal and longitudinal response of the drifting aquatic macroinvertebrates to changes in their habitat as a result of high recreational activities in the San Marcos River. Tubing and swimming accounted for most of the recreation activity (>90%).  Across all seasons, Site 1 had the highest drift densities compared to Site 2 and Site 3. CCA result explained 15.3% of the variability in the San Marcos River benthic macroinvertebrate community among vegetation habitats and 23.9% among open substrate habitats. Study results indicated that drift may be dependent on the benthic abundance. Macroinvertebrate drift densities followed the typical circadian pattern observed in other river systems and result indicated no increase in macroinvertebrate drift density during the day when recreation is occurring. Conclusively, Study results indicated that macroinvertebrates at Site 1 and 2 were not impacted by recreation and turbidity. However, Site 3, based on the CCA results indicate that substrate and turbidity are factors influencing the macroinvertebrate community.


    Bio: Ovie Agare graduated from the University of Lagos with a BS in Surveying and Geoinformatics in 2008. His interest for life within rivers in his homeland and a quest to find ways to improve the quality of water at home made him pursue a MS in Aquatic Resources. He joined the MS Aquatic Biology program at Texas State University in the Fall of 2013 and has since worked with Dr. Thom Hardy at the Meadows Center for Water and the Environment.


  • Thesis Defense

    Soil and vegetative associations of heteromyid rodents in central and South Texas with comments on trapping techniques


    Michelle E. Adcock

    Major Advisor:  Dr. Thomas R. Simpson

    Committee Members:  Dr. M. Clay Green, Dr. Richard W. Manning, and Dr. Joseph A. Veech                               

    Tuesday, July 12, 2016; 1:00 PM; Norris Room; Jerome and Catherine Supple Science


    Heteromyid rodents occur in arid and semiarid lands in western North America. Members of this family often form assemblages that are found in habitats with sandy soils and vegetation that offers both open areas and dense shrub cover.  In this study I investigated the soil and vegetative associations for heteromyid communities at the landscape and microhabitat scales in Central and South Texas.  I utilized capture success as a proxy for abundance.  As a minor objective, I investigated the capture success of Dipodomys compactus/ordii, the most trap-shy heteromyid species included in this study.  I trapped for heteromyids for three seasons on two study sites (Guadalupe County and Jim Hogg County) and assessed microhabitat parameters, including herbaceous cover of grasses and forbs, bare ground, leaf litter, and densiometer readings within each treatment.  Treatments were defined as a combination of both land cover and soil type.  For the landscape level analyses, capture success was significantly different per treatment for each species on both study sites.  Heteromyid species either: 1) selected for a treatment, 2) avoided a treatment, or 3) occurred as expected within a treatment based upon the overall availability of the particular land cover category and soil type.  Selection for or avoidance of certain land cover and soil types on the landscape scale could suggest habitat partitioning by heteromyid species.  For the microhabitat analyses, herbaceous cover and bare ground were significant for the capture success of C. hispidus on the Jim Hogg County study site, with a positive trend observed for herbaceous cover (β = 0.1259, R2 = 0.1516, P = 0.0276), and a negative trend observed for bare ground (β = -0.2156, R2 = 0.2477, P = 0.0038).  Microhabitat parameters were not important predictors of capture success on the Guadalupe County study site, perhaps because of a homogeneous landscape, when compared with the Jim Hogg County study site, which offers more heterogeneity for heteromyid species.  For the paired trap study, extra-large folding H.B. Sherman traps had the highest probability of capture success for D. compactus/ordii.


    Michelle Adcock was born in Staunton, VA and earned her B.S. from the University of Tennessee-Chattanooga in 2005 with a major in environmental science and a concentration in biology. Upon graduation, she worked as an educational outreach coordinator at a rescue, rehabilitation, and release marine aquarium for two years. Concurrent with and after this position, she worked as a wildlife and wetland consultant in Florida for seven years. She entered the M.S. program in Wildlife Ecology at Texas State University in fall 2012 working with Dr. Thomas R. Simpson. She and her husband, Zach Adcock, are proud parents to their son, Davis.


    Thesis Defense

    Distribution of phosphorous, forms of phosphorous and physical composition of sediments in four central Texas reservoirs.


    Wayne Waring


    Major Advisor: Dr. Alan Groeger              

    Committee Members: Dr. Alan Groeger, Dr. Vicente Lopes, Dr. Julie Westerlund   

    Thursday, July 7, 3:00 PM, FAB 130


    Phosphorous (P) is a limiting nutrient in many aquatic ecosystems. Generally, most of the P in a reservoir is delivered in the inflowing river(s) as suspended particulates, and eventually settles to the bottom sediments. The P is then alternately sequestered and released through nutrient cycling processes. The purpose of the present study is to evaluate the P content and gross physical composition of sediments in four Texas reservoirs; including one small run-of-the river reservoir (L. Dunlap), and three, large deep-storage reservoirs (L. Amistad, L. Buchanan, and Canyon L.). Surface sediment samples were collected from 31 sites in the four reservoirs and analyzed for total phosphorous (TP), P fractionation and sediment composition including organic matter, calcium carbonate and non-carbonate clastics. Overall, the HCl-P fraction, which is mostly Ca-bound P, was the best predictor of TP among the P fractions. In L. Amistad, clastics content was the physical parameter with the greatest positive relationship to TP. The reservoir also showed distinct differences in the two contributing arms. P was higher in the Rio Grande arm compared to the Devils River arm, as was the clastics content of the sediments. TP in L. Buchanan showed a clear longitudinal increase between the headwaters and the dam. Ca-bound P was the greatest P fraction in all reservoirs except for L. Dunlap, which had a larger proportion of NaOH-P (iron-bound, redox sensitive P). In both Canyon L. and L. Dunlap, OM was the physical fraction with the strongest relationship to TP. L. Dunlap appears to be functioning differently from the other reservoirs regarding phosphorous dynamics. One speculative possibility is that shorter WRT and fewer periods of strong stratification result in limited release of iron-bound phosphorous under anoxic conditions, thereby providing greater retention of iron-bound phosphorous. Information from this study may prove useful in understanding these differences.

     Bio: Wayne Waring is originally from Austin, Texas and a resident of San Marcos, TX for the past 12 years. He attended Texas State University in San Marcos, TX for his B.S in Aquatic Biology. Wayne began the Masters of Science in Aquatic Biology in the Aquatic Resources program at Texas State University in the Fall semester, 2010. While at Texas State, he received the Outstanding Academic Achievement Award in 2013, 2014 and 2015; and the Outstanding Science Education Award in 2015.


     Thesis Defense

    ANALYSIS OF KILL SITE PARAMETERS TO BETTER UNDERSTAND HUNTING BEHAVIORS OF MOUTAIN LOINS (PUMA CONCOLOR)  


    Name: Kendall Jacquelle AuBuchon


    Major Advisor: Dr. Thomas (Randy) Simpson                            

    Committee Members: Dr. Mark Elbroch and Dr. Butch Weckerly       

    July 1, 2016; 2:00 PM; Norris Room; Jerome and Catherine Supple Science


    The understanding of activity patterns and hunting behaviors can provide insight into life history and predator-prey dynamics. The mountain lion, Puma concolor, occupies the largest geographical range of any terrestrial mammal in the western hemisphere. Mountain lions live in a variety of habitats including mixed forests, high elevation plateaus, shrub communities, open steppe, valley bottoms with steep slopes, and riparian habitats. Previous research has shown their activity patterns occur primarily during the nocturnal and crepuscular periods. The primary prey of mountain lions are mule deer and elk, but they also rely on smaller prey such as American beaver and North American porcupine among others. I investigated characteristics of mountain lion kills in response to diel cycle and lunar illumination. Data were collected between March 4, 2011 to April 27, 2015 on a total of 1,234 predation events from 25 different mountain lions fitted with Global Positioning System (GPS) collars in Colorado and Wyoming. My three objectives were: to provide descriptive characteristics on mountain lion kill sites, evaluate selectivity of kills made across the diel cycle and over varying degrees of lunar illumination, and to assess whether there are seasonal differences in the proportion of kills made across the diel cycle, and across the lunar illumination categories. I constructed 95% Bonferroni adjusted confidence intervals and Manly’s alpha selectivity index scores to assess selectivity or avoidance of specific categories. I used R to run chi-square tests and found that there was a significant difference between lunar illumination categories and during the summer season. The greatest proportion of kills occurred during periods with greatest lunar illumination (>90 %). There was a significant difference in prey selection at the lowest level (<10%) of lunar illumination. Diel cycle also had significant effects on mountain lion kills. Understanding mountain lion hunting behaviors will aid in management of this predator as well as management of its prey populations. In an era of technological advances and urban growth and development, these management practices will allow us the knowledge and tools to successfully cohabitate with this iconic species.


     Kendall AuBuchon grew up in Austin, TX and attended high school at McCallum Fine Arts Academy. In spring 2013 she graduated from Texas State University where she received a BS in Wildlife Biology. She worked with Dr. Noland Martin for undergraduate research investigating mechanisms of hybridization in Iris nelsonii. During her undergraduate degree she accepted an internship position working as a field technician in Colorado where she met Dr. Mark Elbroch, who was conducting his own research at the time. She began her MS in Wildlife Ecology at Texas State University in fall 2013 working with Dr. Randy Simpson. She and Dr. Mark Elbroch began collaborating for her MS where she worked on a large dataset investigating different parameters of kill site data from Mountain lions in Colorado and Wyoming.     


    Thesis Defense

    Characterization of IBR5-ROP GTPase (ROP2/ROP6) Interaction in Plant Auxin Response

    Elia Lopez

    Major Advisor: Dr. Nihal Dharmasiri

    Committee Members: Dr. Rachell Booth, Dr. Dana Garcia and Dr. Hong-Gu Kang

    Friday, July 1, 2016; 10:00 AM; Norris Room, Supple Science Building


    The quintessential phytohormone auxin regulates many aspects of growth and development throughout the plant life cycle. Diverse auxin responses occur via multiple distinct and overlapping signaling pathways. It is well documented that auxin exerts control over gene expression by binding its nuclear co-receptors TIR1/AFB family F-box proteins and AUX/IAA transcriptional repressor proteins, thereby promoting polyubiquitination and subsequent degradation of AUX/IAAs and relieving transcriptional repression of auxin-responsive genes. More recently, auxin has also been shown to rapidly activate Rho of plant (ROP) GTPases at the plasma membrane, leading to a variety of cellular responses. The auxin signaling mutant ibr5-1 exhibits reduced auxin-responsive gene expression without accumulation of AUX/IAA repressor proteins, suggesting the dual-specificity protein phosphatase encoded by the gene IBR5 independently regulates the processes of AUX/IAA degradation and auxin-induced gene expression. In a previous screen for IBR5 interactors, a small GTPase was identified, prompting the question of whether IBR5 interacts with the ROP GTPases ROP2 and ROP6, which have been shown to be involved in auxin signaling pathways in the cytoplasm. In vitro interaction assays indicated IBR5 interacts with ROP2 and ROP6, and these interactions were confirmed by co-immunoprecipitation in Arabidopsis thaliana. To assess genetic interaction, ibr5-1 rop6-2 double null mutant was generated. In root growth assays for auxin inhibition of primary root elongation or induction of lateral root formation, the double mutant exhibited auxin resistance similar to the ibr5-1 parent line. Taken together, the results suggest the dual-specificity phosphatase IBR5 physically interacts with the Rho-like GTPases ROP2 and ROP6, and these proteins may function in a common auxin signaling pathway.


    Bio: Elia Lopez graduated from Texas State University in 2013, earning a B.S. in Biology with a minor in Geography. In 2014, she joined the M.S. program in Biology at Texas State University where she is studying plant hormone signaling pathways. During her time in the graduate program, she became a South Texas Doctoral Bridge Program Scholar and received an award for Best Poster at the 20th Annual Department of Biology Colloquium. In the Fall, she will begin pursuing a PhD at the University of Texas Graduate School of Biomedical Sciences (MD Anderson Cancer Center/UT Health Science Center at Houston).


    Thesis Defense

    THE PREVALENCE OF LEPTOSPIRA IN SMALL MAMMALS ON FIVE PUERTO RICAN CATTLE FARMS


    Name: Kathryn Michelle Benavidez
    Major Advisor: Dr. Iván Castro-Arellano                           

    Committee Members: Dr. Dittmar Hahn, Dr. David Rodriguez, and Dr. Joseph Veech      

    July 1, 2016; 9:00 AM; Room 153; Jerome and Catherine Supple Science


    Leptospirosis is thought to be the most widespread zoonotic disease in the world.  For this study 124 mice (Mus musculus), 99 rats (Rattus rattus and R. norvegicus), and 89 small Asian mongooses (Herpestes auropunctatus) from five farms in Puerto Rico were tested for renal carriage of Leptospira and approximately 38% of the sampled individuals were positive I evinced a heterogeneous distribution of Leptospira prevalence among the sites with a farm in Lajas having the highest prevalence at 52%.  Among tested species, mice had the highest prevalence of Leptospira at 59% and mongooses had the lowest at 13%.  Comparative sequence analysis of the LipL32 gene revealed the presence of two species of Leptospira: Leptospira borgpetersenii and Leptospira interrogans.  These two Leptospira species were equally distributed at all farms except for a farm at San Sebastián where 100% of the samples sequenced were of the species L. borgpetersenii.  Significant associations of Leptospira prevalence with landscape features were observed at a farm in Naguabo, where more positive samples were located near all the tested landscape features and at a farm in Sabana Grande where more positive samples were found near a human dwelling. These results show that rural areas of Puerto Rico are in need of management and longitudinal surveillance of Leptospira in order to prevent continued infection of Leptospirosis by focal susceptible species (i.e. humans and cattle).


    Michelle Benavidez was raised in South Texas and attended high school at Skidmore-Tynan ISD.  In Spring 2014 she graduated as a McNair Scholar from St. Edward’s University in Austin, TX where she received a BS in Environmental Science and Policy with a concentration in Biology and a minor in Sociology.  For her undergraduate research she worked with Dr. Peter Beck to investigate the effects of border fence construction on ocelot conservation efforts in Texas.  She began her MS in Wildlife Ecology at Texas State University in Fall 2014 working with Dr. Iván Castro-Arellano to investigate the role of the small mammals in disease transmission on the island of Puerto Rico.  Fall 2016, she will begin a PhD program at Indiana University in Bloomington where she will join Dr. Michael Wasserman’s Primate Environmental Endocrinology Lab in the Anthropology Department.


    Thesis Defense


    Fitness of Escherichia coli when in Mixed Culture with Enterococcus faecalis


    Avry Stolzman


    Major Advisor: Dr. Robert JC McLean  

    Committee Members: Dr. Kavita Kakirde and Dr. Kelli Palmer (UT Dallas)

    Thursday, June 30, 2016; 1:00 PM; Norris Room, Supple Building


       Escherichia coli (E. coli) coexists with many different species, such as Enterococcus faecalis (E. faecalis), in the gastrointestinal tract of many animals Under normal circumstances, the two bacteria live alongside each other and a multitude of other microorganisms without causing infection. However, there are occasional instances when an imbalance occurs and certain flora are able to outcompete the rest. These superior bacteria express specific traits that allow them to increase colonization and infect the host organism. There is currently little known about the mechanism of how E. coli is able coexist. Using the Keio collection of E. coli, we identified that the gene yliK in E. coli, commonly known as methylmalonoyl CoA mutase, that is essential for its growth when in mixed culture with E. faecalis. Methylmalonoyl CoA mutase is part of a four gene operon encoding for enzymes that convert succinate into propionate. The E. coli mutant pure culture exhibited increased fitness with the addition of propionate. The E. faecalis, although at a much lower cell density, also exhibited increased fitness with the addition of propionate. The E. coli mutant/E. faecalis mixed culture showed to have increased fitness when grown together as when compared to the fitness of the two bacteria in pure culture. The E. coli mutant/E. faecalis mixed culture also showed an increase in fitness with the addition of propionate. These results suggest that E. coli and E. faecalis increase the other’s fitness, and that this elevated fitness is enhanced when propionate is added to the environment.


    Bio: Avry Stolzman is a hill country native, growing up in Johnson City, Texas. She graduated from Tarleton State University in 2013 with a B.S. in Biology. She began her M.S. in 2014 studying the relationship between Escherichia coli and Enterococcus faecalis in mixed culture. She will be attending Ross University School of Veterinary Medicine in September of 2016.


    Thesis Defense


    Salmonellae in the intestine of H. plecostomus in the San Marcos River


    Name: Anna Y. Gates
    Major Advisor: Dr. Dittmar Hahn

    Committee Members:   Dr. Robert McLean and Dr. Thom Hardy

    Thursday, June 30, 2016, 9:00 am, Supple 153


    Heavy rainfall events have been associated with outbreaks of many waterborne diseases including salmonellosis. Salmonellosis is caused by members of the genus Salmonella that can enter water systems through sewage contamination, runoff after heavy rainfalls, or flow-through channels through manure fields after heavy rains or flooding.  Currently, salmonellae are not closely monitored in regards to water quality.  In this study, Hypostomus plecostomus, an invasive, algae consuming fish, was sampled from the San Marcos River (San Marcos, TX), the intestines analyzed for the presence of salmonellae by quantitative real-time polymerase chain reaction (qPCR) after semi-selective enrichment, and results related to precipitation and other ecological factors affecting the river area.  Salmonellae were detected in the intestines of H. plecostomus in 40-100% of the fish following most precipitation events, but were not consistently detected in environmental samples (i.e. water and sediments).  Other ecological factors affecting the river do not appear to play a significant role in the prevalence of salmonellae in the intestines of H. plecostomus.  This leads us to believe that H. plecostomus is ingesting salmonellae through their food sources and that the amount of salmonellae present in those food sources may be increasing after large rainfall events, but may not be dependent on these events. 

    Further studies included characterization of Salmonella isolates from positive samples by repetitive polymerase chain reaction (rep-PCR).  Unique isolates were then serotyped using Multilocus Sequence Typing (MLST).  Several sampled H. plecostomus were observed to be infected by multiple serotypes of Salmonella, whereas other positive fish were observed to be infected by one serotype only.  Some serotypes were observed to be common across multiple sampling dates, which leads us to believe that there may be a common environmental serotype residing in the intestines of infected H. plecostomus.  Furthermore, detection of multiple serotypes in the intestines of H. plecostomus was an unexpected observation.          


    Anna Gates received her Bachelor’s degree from the University of Houston – Downtown in microbiology in 2012, where she participated in undergraduate research studying dental biofilms and stress on B cell lymphocytes.  She started the Master’s degree program and joined Dr. Hahn’s lab in 2014, studying microbial ecology and the prevalence of salmonellae.  She will be joining Michigan State University to pursue a Doctor of Veterinary Medicine degree in August 2016.  


    Thesis Defense

    Histone variant H2A.Z substitution mediated by the SWR1-like complex is a novel transcriptional regulatory mechanism controlling defense genes and immunity in plants


    April Bonnard


    Major Advisor: Dr. Hong-Gu Kang            

    Committee Members: Dr. Nihal Dharmasiri and Dr. Sunethra Dharmasiri          

    Friday, June 24, 2016; 2:00 PM; Norris Room, Supple Building


     Plants have evolved a complex immune system against various pathogens, part of which involves the function of resistance (R) proteins in detecting the presence of secreted effector molecules from pathogens. This detection leads to a robust immune response by implementing large-scale modifications in chromatin accessibility, thus leading to transcriptional reprogramming. MORC1 is a protein that interacts with several of these R proteins and is required to maintain optimum levels of immunity in Arabidopsis. MORC1 is also a putative chromatin-remodeling factor as it has been shown to exhibit ATPase and endonuclease activity and that its subpopulation localizes to the nucleus after pathogen infection. In this research, I aim to characterize the interaction of MORC1 with the components of the SWR1-like complex, including ACT1, ARP4, SWC2, SWC5, SWC6, SUF3, PIE1, RVB1, and YAF9 in Arabidopsis. The SWR1-like complex replaces histone H2A with its variant H2A.Z. This replacement has been speculated to be involved in transcription regulation as it occurs in the promoter and/or genic region of actively transcribed genes. Interestingly, a wide range of mutations in these SWR1-like components led to altered resistance to the bacterial pathogen Pseudomonas syringae, suggesting that the SWR1-like complex functions in plant immunity. To further gain insight into the molecular mechanism of this H2A.Z replacement in defense signaling, I performed chromatin immunoprecipitation with H2A.Z and found that pathogen infection leads to the association of H2A.Z with defense genes including PR-5. Furthermore, an Arabidopsis mutant line lacking three genes encoding H2A.Z showed compromised transcriptional induction of defense genes in response to pathogen infection. Together, my results establish that the histone replacement with H2A.Z by the SWR1-like complex modulates the transcription of defense genes and thereby affects immunity in plants. A potential model how this histone replacement can be implicated in transcriptional memories in which a prior stress exposure often leads to more prompt transcriptional induction to similar stress will be discussed.


    Bio: April Bonnard graduated from Texas State University in 2014 earning a B.S. in Biology with a minor in Biochemistry. She is now pursuing her M.S. in Biology at Texas State University where she is studying the relationship between chromatin-remodeling and plant immunity. During her time in the M.S. program, she became a member of the Alpha Chi National College Honor Society and participated in the 20th Annual Department of Biology Colloquium, where she received an award for the best talk at the M.S. level.


    Thesis Defense

    Effects of red imported fire ants (Solenopsis invicta) on juvenile Houston toads (Bufo houstonensis) in coastal prairie grassland

    Name: Madeleine Marsh

    
Major Advisor: Dr. Michael Forstner

    Committee Members: Dr. Thomas Simpson and Dr. Clay Green

    Wednesday, June 22, 2016, 10:00 am, Supple Norris Room

    The Houston toad (Bufo houstonensis) was first described in 1953 in Houston, Texas, but has since been extirpated from the area. Houston toad populations have been in a nearly continuous decline across their known distribution since discovery, primarily due to multiple stressors, including red imported fire ants (Solenopsis invicta; hereafter referred to as RIFA).  In spite of the uncertainty of historical presence, the 1984 Recovery Plan attempted to reintroduce the Houston Toad into coastal prairie habitats.  Although originally thought unsuccessful, the Recovery Plan site proved to be suitable habitat, even if only as dispersal habitat. In 2015, on Attwater Prairie Chicken National Wildlife Refuge (APCNWR), a total of forty-eight exclosures were placed in four prairie locations (12 exclosures per site) two of which were treated for RIFA and two prairie locations were used as untreated controls. Morphometric data (snout-urostyle length, head-width, and weight) were collected for all toadlets were detected on a weekly basis, slowing to bi-weekly after six weeks.  A mixed-effects for repeated measures model was used in R to evaluate growth rates between treatment and control areas, which showed no difference in growth between treatments (f = 1.747, df = 42.7, 45, p = 0.09) or density (t = -1.095, df = 140.61, p > 0.1). Program MARK was used to estimate survivorship and detection between treatments using a Cormack-Jolly Seiber (CJS) model.  The model chosen, using ΔAICc, assumed that detection and survivorship changed through time but not between treatments.  Because there was no difference in growth or survivorship, we fail to reject our null hypothesis that RIFA has a negative impact on the survival and growth of juvenile Houston Toads. A trend seen in the data comparing the exclosures in the open prairie to those within the drip line showed higher survival within the drip line, but much faster growth in the open prairie.  This supports that connectivity of habitats is vital for the survival of juvenile Houston toads.  However, because it has been shown that Houston toads are able to persist on the RIFA controlled prairies of APCNWR, the area of suitable Houston toad habitat can now be more explicitly delineated to include native grasslands, particularly for dispersal habitat.  These landscape-connecting habitats are one of the most critical and least understood ecological aspects for Houston toad management. The results from this study also clearly assist with assessing new sites for reintroduction through propagation and population restoration efforts.


    Thesis Defense

    Site factors influencing drought-related tree mortality in Central Texas


    Name: Beth Crouchet


    Major Advisor: Dr. Susan Schwinning              

    Committee Members: Dr. Benjamin Schwartz and Dr. Jennifer Jensen

    Wednesday, June 15, 2016, 1:00 pm, Supple 153


    Climate models predict an increase in the frequency of severe weather events, including prolonged drought conditions coupled with exceptionally high temperatures. These so called “global-change-type” drought events have been linked to numerous forest dieback events worldwide. Texas experienced such an event in 2011, which reportedly killed 6% of all trees in the state. The purpose of my research was to identify site factors that modified local rates of tree mortality. In 2014, I censused 64 plots across the state, of which 40 were included in the final analysis focusing on Central Texas. Over 6000 trees were included, mostly in the genera Juniperus (n=3487), Quercus (n=1054), Ilex (n=745), Ulmus (n=347) and Diospyros (n=308). Each tree above 10 cm circumference was identified to the species level, its basal circumference was measured and its health status recorded in seven categories between dead with no sign of re-sprouting to < 25% crown die-back. For each plot I also collected site variables describing community composition, elevation, slope, aspect, solar insolation, water storage capacity, soil texture and depth, as well as climate factors, including annual precipitation from 2008 to 2011 and daily temperatures in 2011. I used binary logistic regression in a multivariate model selection analysis to determine which factors were significantly correlated with crown dieback and tree mortality.

    The number of days in which trees were exposed to temperatures over 35 or 38°C in 2011 had a significantly positive effect on mortality in three out of nine tree species. Heat exposure had independent effects on crown dieback and on the odds of resprouting. Precipitation in 2011 had significant effects in eight out of nine species, but they were positive for some species and negative for others. Topographic effects (e.g., slope and aspect) were significant for four out of nine species. Collective stand density was not as good a predictor of mortality than species-specific densities. For example, the mortality odds of Juniperus ashei on the Edwards Plateau was more closely related to intraspecific density. Although J. ashei was by far the most common species, Quercus fusiformis was not negatively affected by J. ashei density, but instead by its own intraspecific density and the density of Diospyros texana. Modeling approaches that focus on purely abiotic factors such as climate, topography and soil are incomplete, because they omit the influence of species interactions in diverse communities. My study exposed some of the complexities associated with linking climate events to vegetation changes, in particular, the effects of landscape variation and vegetation composition on tree mortality.


     

    Bio: Beth Crouchet was born in Austin, Texas and earned a B.S. degree in Environmental Science from Concordia University in 2010. She has recently completed the Capital Area Master Naturalist Program where she volunteers as an environmental educator around the Austin area. She is the mother of two boys, ages 11 and 14.


  • Thesis Defense


    The Genomic Architecture of Reproductive Isolation in a Louisiana Iris Hybrid Zone


    Cheng-Jung (Joy) Sung


    Major Advisor: Dr. Noland Martin

    Committee Members: Dr. Chris Nice and Dr. James Ott

    Tuesday, May 31,2016, 10:00am, Supple Science Building, Room 153


    Speciation is a consequence of multiple sequentially-acting pre-zygotic and post-zygotic reproductive isolating barriers that evolve over time. To examine the genomic architecture of reproductive isolation and adaptive introgression, hybrid zones can be used to identify genomic regions that are resistant - or more susceptible - to gene flow in nature as well as to identify the genomic architecture of known reproductive isolating barriers. In the current study, a large Louisiana Iris hybrid zone between Iris fulva and Iris hexagona habitats was identified in Southern Louisiana. This hybrid zone is comprised of individuals with a wide variety of genetically diverse late-generation hybrids that exhibit an array of flower-color and plant-growth morphologies. The two Iris species are differentiated with respect to floral traits morphologically, which results in the attraction of different pollinators, and ecologically, which results in habitat isolation. Ecological isolation is therefore one of the most important barriers preventing gene exchange between these Iris species.

    In this defense, I will describe how Bayesian Genomic Cline analyses can be used to identify loci responsible for reproductive isolation and adaptive introgression in Louisiana Iris. I also will show how Genome Wide Association Mapping can identify the genomic architecture of floral and ecological traits that differ between I. fulva and I. hexagona. I will then combine these two analytical approaches to ask the following question: “Do the genomic architectures of phenotypic traits predict patterns of gene flow in hybrid zones?” In short, the answer is “yes”. The genomic architectures of 14 traits that were examined were complex, with many loci of small effect explaining phenotypic differences observed between species. Further, these loci were significantly associated with reproductive isolation between, and adaptive introgression across species boundaries.


    Bio: Cheng-Jung Sung was born and raised in Taipei, Taiwan and received her Bachelor’s degree of Science at National Taiwan University in Crop Breeding of the Department of Agronomy in Taiwan in 2011. She attended Texas State University and started her Master’s study in the Population and Conservation Biology program of the Department of Biology in 2012 and has been working with Dr. Noland Martin since then. She plans on integrating her two fields of study to pursue her PhD degree.


    Dissertation Defense

     

    Personality and predation in a changing environment


    Name Chelsea Blake


    Major Advisor: Dr. Caitlin Gabor           

    Committee Members: Dr. Chris Nice, Dr. Andrea Aspbury, Dr. Alison Bell, Dr. Brian Langerhans

     

    Friday, 15 April 2015, 2:00pm Supple Science Building 116


    The interaction between predators and prey is one of the driving forces that shape not only animal behavior, but also the evolution and ecology of organisms. However, predator-prey interactions are now taking place in an unprecedented and rapidly changing world, as humans introduce new species and alter habitat conditions. Thus examining the anthropogenic introduction of novel predators is key to the contemporary study of behavioral ecology. Further, not all individual animals behave the same way within the same species or population, thus it is important to also assess behavior at the level of the individual. Individual behavioral types, or "personalities" of animals can have far-reaching implications for their ecology. Here I have explored predator-prey interactions in the context of changing environments from the perspective of individual-level variation to provide novel insights into species interactions. I have found that the personality of prey can affect how they fare with predators, but that the effect depends on which predator species they face. Additionally, I have shown that although behavioral type is important in predator interactions, it does not affect whether prey are able to recognize a novel predator. I have also explored how physical antipredator characteristics of individuals might relate to their behavioral type. I have found that although physical traits are not necessarily inherently correlated with behavioral traits, altering the physical condition of an individual can affect their behavioral traits. Ultimately, my work contributes to the understanding of how prey personality could interact with introduced predators to either aid or hinder the survival of native species.


    Bio:  Chelsea was born in Evanston, IL and grew up in Indianapolis, IN. At Earlham College, a Quaker liberal arts school, Chelsea studied metal working and biology. After graduating in 2008, Chelsea spent several years working in environmental education and ecology around the nation before starting a PhD program at Texas State in 2011. In 2013, Chelsea won a National Science Foundation fellowship, which facilitated the creation of the Project SPRING science outreach program at Texas State. Chelsea’s parents, sister, spouse, Augustyn Blake, and choir friends at Crystal Queer Revelation have been very supportive throughout these years.


    Thesis Defense


    Title: Effects of Abiotic Factors on Body Size Class Variation of Lepidoptera in Two Contrasting Ecosystems: the Chihuahuan Desert and Edwards Plateau 


    Name: Virginia Brown


    Major Advisor:  Dr. Michael Huston  

    Committee Members:   Dr. David Huffman and Dr. Chris Nice

     

    Wednesday, April 6, 2016, 2pm, Supple 257


    The abundance and body sizes of organisms are expected to respond to environmental conditions such as temperature, precipitation, and food availability.   I quantified the abundance and total mass of nocturnal lepidoptera across multiple size classes to determine whether lepidoptera of different sizes responded differently to environmental conditions. Standardized samples were collected from two contrasting ecosystems – the Chihuahuan Desert in the Big Bend region and the Edwards Plateau near San Marcos. During 2013 the Chihuahuan Desert was sampled at two sites, a mountain hillside and a mesquite flat, near Terlingua Ranch headquarters at the base of the Christmas Mountains. Synchronously two sites, an open grassland and an oak-juniper thicket, were sampled at Freeman Ranch near San Marcos, Texas. Samples were sorted to morphospecies, counted, dried and weighed. Body size classes were evaluated in terms of total number of individuals, total weight and morphospecies. Available abiotic factors were not strong predictors of body size patterns. Total abundance and weight followed seasonal precipitation patterns at both locales.   Body-size classes were more strongly correlated to each other in the Chihuahuan Desert than in the Edwards Plateau, probably as a result of the contrasting seasonal precipitation patterns. Our research establishes a baseline of comparison for the Chihuahuan Desert; while demonstrating that there are complex interactions between the lepidoptera community and abiotic factors that warrant further investigation. 

    I evaluated how the body size distribution of lepidoptera were affected by abiotic factors; average and accumulative monthly temperature, growing degree days, precipitation, and temperature at time of sampling. To determine if the response was due to phylogeny of the order, rather than environmental factors.

    ___________________________________________________________________________________________

    Virginia Brown became interested in studying insects while traveling through the outback of Australia. She joined the Huston Terrestrial Ecology lab as a junior, and helped establish entomological research at the Christmas Mountains. Enjoying her undergraduate research in the Chihuahuan desert she decided to remain at Texas State University for her Masters in Biology with a focus on lepidoptera ecology.


    Thesis Defense


    Potential role of stygobitic species in nutrient dynamic of the Edwards Aquifer, central Texas


    Lauren A. Loney


    Major Advisor: Dr. Weston Nowlin  

    Committee Members:  Dr. Floyd Weckerly, Dr. Benjamin Schwartz

     

    Wednesday, April 6, 1:00PM, Freeman Aquatic Building 130


    In aquatic ecosystems, animals can have direct and indirect impacts on the cycling of nutrients. In subterranean aquatic ecosystems with little to no direct connection to the surface, the recycling of organic matter and inorganic nutrients is likely to be particularly important in maintaining below ground communities.  Although numerous studies have examined the role of consumer-driven nutrient cycling in surface aquatic ecosystems, relatively little is known about the ecology and nutrient cycling dynamics of subterranean ecosystems.  In this study, I examined the nutrient recycling and body stoichiometry of the stygobiont (obligate subterranean aquatic organisms) community located at a site within the Edwards Aquifer, one of the world’s most diverse aquifers.  The first goal of my study was to examine the diversity and composition of stygobionts at my study sight and to gain information on which stygobiont species were numerically- and biomass-dominant in this portion of the Edwards Aquifer.  The second portion of my study examined nutrient recycling (via excretion) and elemental composition of several common invertebrate stygobiont species in my study portion of the aquifer.  I also compared stygobiont nutrient recycling and stoichiometry to related epigean taxa collected from the San Marcos River. Overall, I found that the stygobiont community at my study site was relatively species rich, but it numerically dominated by few taxa.  I also found that stygobiont excretion varied significantly with body size and species identity, but that species origin (epigean vs stygobiont) did not have a substantial role in predicting nutrient recycling and elemental composition.


    Bio: Lauren Loney is from San Marcos, Texas. She graduated from the University of Missouri in 2011 with a B.S. in Fisheries and Wildlife. Lauren began her Master’s of Science in Aquatic Resources at Texas State University in the fall semester of 2012 and is currently pursuing a Juris Doctor from the University of Texas with an emphasis in water law. 


    Thesis Defense

    Urbanization and Stress Response of Texas Eurycea Salamanders


    Name: Megan J. Mondelli


    Major Advisor: Caitlin R. Gabor, Department of Biology, Texas State University 

    Committee Members: Chris Nice, Department of Biology, Texas State University

    Andrew Gluesenkamp, Texas Parks & Wildlife and Nathan Bendik, Watershed Department, City of Austin

     

    Wednesday, April 6, 2016, 9AM, Supple 153

     


    Amphibians worldwide are rapidly declining. Successful conservation strategies should consider the physiological response of an organism to its environment using stress hormones. Glucocorticoid (CG) hormones are a particularly useful class of biomarkers that effectively measure stress. The primary GC stress hormone in amphibians is corticosterone (CORT). Short-term increases in CORT (i.e., acute stress) are adaptive during stressful events because CORT mediate metabolic and immune function. However, chronic stress can be harmful to the overall health of an organism and can lead to dysregulation of the hypothalamic-pituitary-interrenal (HPI, for amphibians) axis leaving the organism susceptible to metabolic and immune problems. Chronic stress is also associated with suppressed reproductive hormones such as testosterone and estradiol. Anthropogenic and environmental factors such as seasonal changes, urbanization (modification, pollution) and storms have been shown to affect stress and reproductive hormones. Here, I studied how these factors affect the stress of two federally threatened species of Texas Eurycea salamanders that are fully aquatic. I conducted two projects, the first of which measured stress levels of E. tonkawae, Jollyville Plateau salamander, in urban and rural streams across seasons. I also examined the correlation between stress, sex steroids and activity levels of salamanders in urban and rural streams. My second project investigated the effects of storm water runoff on stress of E. nana, San Marcos salamander. I found that CORT in E. tonkawae is highest in summer but did not vary based on stream type. Activity in E. tonkawae varied by population; one urban stream showed a positive correlation between activity and CORT while but this was not the case in the other populations. However, urbanization did not affect activity level. Additionally, my research shows a significant effect of storm runoff water on testosterone, but not CORT in E. nana. In conclusion, my research shows that CORT changes with season and should be considered when testing other questions stress response. Additionally, it is possible that storm water does not affect the stress of salamanders, but some other factor associated with storm events might be stressing these salamanders. Further research is needed to tease out what factors maybe stressful.


    Bio:  Megan J. Mondelli graduated from Rowan University (New Jersey) in 2013 earning a B.S. in Biological Sciences. During her undergraduate degree in 2012, she received a National Science Foundation funded REU position to explore population distributions and prey type of Plethodontid salamanders in New Hampshire. After, graduating, she worked for Rutgers University at Haskin Shellfish Research Laboratory participating in an oyster stock assessment survey for the Delaware Bay. In 2014, Megan began pursuing a M.S. in Population and Conservation Biology at Texas State University, studying how urbanization affects the seasonal variation in hormones and behavior and how runoff from storms affects hormones of Texas Eurycea salamanders.

     


     

    Thesis Defense

     

    Patch Occupancy and Population Density of the Crevice Spiny Lizard (Sceloporus poinsettii) in the Central Mineral Region of Texas


     

    Name: Jeffrey T. Jenkerson

    Major Advisor: Thomas R. Simpson, Department of Biology, Texas State University        

    Committee Members: Ivan Arellano-Castro, Department of Biology, Texas State University, James F. Gallagher, Texas Parks & Wildlife

     

    April 4, 2016, 1:00 PM, Supple 153


    Herpetofaunal species within a landscape are strongly associated with the amount and availability of suitable habitat as defined by numerous characteristics of the microhabitat. I estimated occupancy and density of crevice spiny lizards (Sceloporus poinsettii) on monadnock features present on Mason Mountain Wildlife Management Area within the Llano Uplift area of the Central Mineral Region of Texas. From June to September 2015, I captured and marked 46 adult crevice spiny lizards using ®Floytag T-bar anchor tags. Average lizard density across sites was 1.41/100 m2 (SE = 0.023, n = 46).  Additionally, 382 lizards were detected across 20 locally isolated granitic outcrops during abundance sight surveys. These estimates were used to evaluate the relative influences of microhabitat variables on the distribution of this rock-dwelling lizard species within the context of habitat size and a landscape level variable (burning treatment). I measured variables that are either known or suspected to influence habitat suitability, including fine-scale rock habitat (i.e. ground cover, geology, amount of refuge and vertical surface area) and the landscape context (burning treatment). Multimodel information-theoretic approach suggests that at a local rock scale, crevice spiny lizard occupancy may be more closely related to refuge quality. At a boundary habitat scale, most parsimonious models suggest that geographic aspect is most influential to occupancy. These results indicate that patterns of occurrence may be tied closely to characteristics most immediately affecting the ability to thermo-regulate and find cover. Lizard density decreased with increasing site size, indicating that habitat size may not be positively correlated with habitat suitability for the crevice spiny lizard.


    Bio:  Jeffrey T. Jenkerson graduated from the University of Texas at San Antonio in 2013 earning a B.S. in Biology with a concentration in Ecology. In 2014, Jeffrey began pursuing a M.S. in Wildlife Ecology at Texas State University, studying how habitat parameters affect crevice spiny lizard demography.


    Thesis Defense


    Inducing Biofilm Dispersion


    Name: Sara Robertson


    Major Advisor:    Dr. McLean          

     

    Committee Members: Dr. Forstner and Dr. Rodriguez   

     

    Monday, April 4, 2016  9am Supple Norris Room


    Bacterial growth on surfaces results in these organisms forming a complex surface-adherent biofilm community. Growth as biofilms results in  microorganisms becoming highly resistant to most antibiotics and disinfectants. In this study I explore an alternative method for biofilm control by inducing dispersion of sessile organisms into an unattached (planktonic) growth mode using boric acid. Samples used were naturally-occurring aquatic biofilms from gravel in the San Marcos River. Biofilm concentrations and detachment due to exposure to boric acid (experimental) or water (control) was measured using dilution plating and growth on R2A agar. The study further explored the effects of dispersion by examining if a preferential release of certain bacterial taxa is induced. To determine whether boric acid induced a preferential removal of bacterial populations from aquatic biofilms, DNA was purified from biofilm samples prior to and following treatment with either boric acid or water, as well as from bacteria released through these two treatments. Using Illumina Miseq sequencing, community profiles of bacterial populations were obtained and showed the population released by boric acid treatment was similar to the original biofilm population. In contrast, the population released by water treatment showed a preferential release of microbes among taxa. Future implication for dispersion could be useful in food processing equipment, medical equip and long term goals of rejuvenation of older antibiotics.


    Bio: Sara is from Georgetown TX. After high school she served 4 years active duty in the U.S. Navy and an additional 3 years as an active service reservist. After completing her active duty tour she studied wildlife and fisheries at Texas A &M and received a B.S in 2009. Sara then started her Master in the fall of 2014 and will be graduating May 2016 with a M. S. in Biology. 


    Thesis Defense


    Social factors during foraging bouts influence sexual segregation


    Leah Peterson


    Major Advisor: Dr. Floyd. W. Weckerly            

    Committee Members:  Dr. Mark A. Ricca, Dr. Tim H. Bonner

    Friday, April 1, 2016, 1:00PM, Supple Science Building 257


    Large ungulate spatial patterns occurring at broad scales can often be explained by fine-scale processes that function at the individual level. To better understand broad-scale sexual segregation, fine-scale processes were examined in a non-migratory population of Roosevelt elk (Cervus elaphus roosevelti) in the Redwood National and State Parks, California, USA. Throughout twenty years of observation, this population exhibited a change in sexual segregation, allowing the opportunity to assess the potential influence of two fine-scale mechanisms: the availability of forage abundance and social factors during the forage bout. Per capita forage availability was estimated for comparison between two meadow complexes (2005-2016) to determine if selectivity for one meadow complex by males (and thus sexual segregation) could be explained by the greater absolute metabolic requirements in males. To assess the influence of social factors (such as group size, group type, or proximity of conspecifics) during the foraging bouts, focal observations were collected from adult male and female elk from 2009-2016. These data were used to conduct AIC analyses to select the best fit models for predicting the distance traveled, the variance in turning angles, and the proportion of time the animal spends with its head out of the feeding position during a foraging bout. Interestingly, we found that the availability of forage biomass was likely not the driver for males and females using separate meadow complexes. This study instead found that males are more vigilant than females and are more likely to move farther and in direct paths to avoid proximity of conspecifics. Consequently, males will be more influenced by social factors while foraging than females. The asynchronous responses to social factors by males and females may explain the exclusive, male-only use of a meadow complex from which females were recently extirpated. We can therefore conclude that sexual segregation is driven, in part, by fine-scale foraging behaviors.


    Bio: Leah Peterson is originally from Des Moines, IA. She attended Creighton University in Omaha, NE and achieved her B.S. in Biology in 2013. Leah began her Wildlife Ecology Master’s program at Texas State in the fall of 2014 and with her M.S. degree, she hopes to pursue a career in wildlife research or consultation.


    Thesis Defense


    Density-Dependent not -Independent Factors Influence Roosevelt Elk Recruitment in the Bald Hills of Redwood National Park


    Nicholas R. Kolbe


    Major Advisor: Dr. Floyd. W. Weckerly            

    Committee Members:  Dr. Thomas R. Simpson, Dr. Mark A. Ricca

    Friday, April 1, 2016, 9:00 AM, Supple Science Building 257


    Density-dependent and ­­-independent factors are known to influence population dynamics of large ungulates like Roosevelt elk (Cervus elaphus roosevelti). But the strength of influence of both kinds of factors depends on abundance relative to K carrying capacity. I examined the influence of density, climatic variables and prescribed fire on juvenile recruitment in an elk population in Redwood National Park, California, USA, from 2002 to 2015. In the Park prescribed fire is used to reduce conifer and redwood (Sequoia sempervirens) encroachment into meadows and is not used to manage elk habitat. Consequently, prescribed fire might have a density-independent influence on juvenile recruitment and population dynamics. Fire is also known to increase elk food supplies but whether fire might have a positive influence on recruitment depends on the population size relative to K. Between 2002 and 2015 abundance varied from 190 to 279. Using a Gompertz state-space model and expectation from the standard logistic model I estimated K to be between 275 and 340. An Akaike Information Criterion model selection analysis of 35 linear regressions estimating juvenile recruitment considered abundance, prescribed fire, and climatic influences. Population abundance alone had the strongest influence on juvenile recruitment. Our findings may be affected by the population being below K carrying capacity. Prescribed fire might not have influenced recruitment because the population was too far below K or an insufficient area was burned to substantially increase elk food supplies.


    Bio: Nicholas Kolbe is from McQueeney, Texas. He graduated from Texas A&M University of Kingsville in Kingsville, TX with a B.S. in Range and Wildlife Management. Nicholas began his Masters of Science in Wildlife Ecology at Texas State University in the fall semester, 2014. While at Texas State, he has presented two papers at the Texas Chapter of the Wildlife Society annual meetings and published a manuscript in California Fish and Game. During the summer of 2015, he worked as an intern for Texas Parks and Wildlife Department at the Gus Engeling Wildlife Management Area, Tennessee Colony, TX. Nicholas has also received numerous scholarships from Texas State and non-governmental organizations.


    Thesis Defense

    The ecology of colonial nesting Green Herons (Butorides virescens) in Texas


    Name: Nathan Trimble


    Major Advisor:   Dr. M. Clay Green           

    Committee Members:   Dr. David Huffman, Dr. Floyd Weckerly

     

    Wednesday, March 30, 2016, 2PM, Norris Room


    Green Herons (Butorides virescens) are small herons found throughout the eastern United States, the west coast of the United States and throughout most of the state of Texas. While this species can be found along the Texas Coast year round, they occur in greater densities during the breeding season. Green Herons are solitary foragers and often nest singly, with a breeding pair defending a breeding territory. Green Herons sometimes form loose breeding aggregations or colonies presumably as a function of habitat availability and/or predator pressure. A colony of at least 35 breeding pairs of Green Herons annually breed along a tidal creek in Port Lavaca, Texas. This study sought to determine a relationship between nest density and nest success and to use observational data to examine factors of this poorly understood behavior in Green Herons. A secondary goal of the study was to examine juvenile dispersal by banding chicks and monitoring adults in subsequent years to test whether juveniles return to their natal colony to breed. Nearest neighbor spacing varied from < 1 m to 42.5 m apart (mean=9.57m). All nests occurred in low shrubs Marsh Elder (Iva frutescens) along the water’s edge. Nesting began in early April and ceased in late July/early August. Clutch size ranged from 1-5 eggs for both years with a mean of 3.09 (SE=0.106) and 3.43 (SE=0.163) for 2014 and 2015 respectively. Nest success varied between years (2014, 53.57% nest success; 2015, 12.25% nest success); high nest mortality in 2015 was likely due to extreme weather events and human disturbance. AIC model selection favored models containing the quadratic effect of nearest neighbor estimate, Julian lay date, and year suggesting the possibility of an optimum nearest neighbor distance of around 12m for Green Herons at this location, though more years of data will be needed to reveal a strong trend given the high amount of density independent mortality in 2015. No chicks banded in 2014 were re-sighted in 2015.


     Nathan Trimble grew up in Houston, TX. He received a Bachelor’s of Science in Wildlife Biology from Lees-McRae College in Banner Elk, NC. Nathan got hooked studying birds in the mountains of North Carolina and joined the Wildlife Ecology program at Texas State University in fall of 2013 with a focus on avian ecology.


    Thesis Defense


    Using nutrients, sediment, ions, isotopes, and hydrograph separation to quantify conduit-dominated recharge processes in a Trinity Aquifer site: Cave Without a Name


    Michael Markowski


    Major Advisor: Dr. Benjamin Schwartz     

    Committee Members: Dr. Weston Nowlin, Dr. Astrid Schwalb

    Wednesday, March 30, 8:30 AM, Freeman Aquatic Building 130 (FAB 130)


    Cave streams provide an ideal location for sampling waters transported through a karst system because they integrate basin-wide sources ranging from fast flow in conduits to slow flow through the bedrock matrix. Although numerous studies have monitored cave streams to characterize these process, most have infrequent sampling intervals and/or a limited number of measured parameters. This study used a large dataset that includes high frequency sampling and comprehensive stormwater analyses of surface and cave stream water from five storm events between July 2014 and July 2015 at Cave Without A Name (CWAN) in central Texas.  The objectives were to determine which environmental factors influence the timing and proportions of storm water and pre-event water moving through the system and to quantify relationships between discharge and sediment, nutrient, and ion concentrations within and across storm events. Results show that evapotranspiration (summed over prior 12 weeks to each storm), soil moisture (at 10-40cm), and cave-stream discharge prior to each storm affects the timing of the peak ratio of stormwater/pre-event water flow through the cave. As antecedent conditions became wetter from July 2014 to July 2015, peak stormwater arrival times dropped from days to hours. Progressively faster stormwater arrival times, heterogeneity within and across storm chemographs and sediment graphs, and water isotope data all indicate a flushing of the upper unsaturated zone during Events 1 and 2, and progressive wetting of unsaturated portions of the system from July 2014 to July 2015. Taken together, these data reveal complex hydrologic and mass transport dynamics, variable rainfall-runoff and rainfall-recharge relationships, and highlight that a single storm cannot be used to accurately describe how a karstic groundwater system responds to storm events under a wide range of hydrologic conditions.  This better understanding of recharge processes at CWAN will help guide future research and surface water/groundwater management in karst regions.


    Bio:  Michael Markowski attended The University of Texas and received a B.S. in Hydrogeology in 2010. He spent two years at the Pickle Research Campus, where he worked with both fluvial geomorphology and glaciology teams. He plans on completing his M.S. in Aquatic Resources from Texas State University this May.


    Dissertation Defense

     

    Influence of Brain-Derived Neurotrophic Factor and Family History of Alcohol Dependence on Alcohol USE IN Healthy Social Drinkers


    Shobhit Sharma


    Major Advisor: Dr. Natalie Ceballos

    Committee Members: Dr. Dana Garcia, Dr. Brett Ginsburg, Dr. Michelle Lane and Dr. Shannon Weigum

     

    Monday, March 28, 12:00 Noon, Supple Science Building Norris conference room


    Brain-derived neurotrophic factor (BDNF) is important for neuronal survival, differentiation and consolidation of synaptic strength. Studies have found increased alcohol use and genetic risk for alcohol dependence in individuals with the Val66Met single-nucleotide polymorphism (SNP) of the BDNF gene, a genotype associated with decreased activity-dependent release of BDNF. However, the literature remains contentious with regard to this issue. The current study was designed to address this issue with two aims. Aim 1 examined the influence of the Val66Met SNP, serum BDNF levels, and family history of alcohol dependence (FH) on alcohol use in healthy social drinkers. It was expected that the Val66Met polymorphism would be associated with higher drinking levels compared to the Val66Val genotype, and those participants with a combination of Val66Met genotype and a positive FH would exhibit the most severe alcohol use profile. Results for Aim 1 indicated no significant effects of genotype on quantity/frequency of alcohol use; however, the Val66Met group had an earlier age at first alcohol use. FH-positive participants had an earlier age at first drunken episode. There were no interactions of BDNF genotype x FH group. Correlational analyses revealed that quantity/frequency of alcohol use was positively related to perceived stress levels in the Val66Met group, such that participants with higher stress levels tended to consume more alcohol. This relationships was not present in the Val66Val group. Aim 2 examined stress-related changes in serum BDNF levels. It was expected that Val66Met and Val66Val groups would have different stress-related changes in serum BDNF levels, and that the profile of the Val66Met group would be associated with more severe alcohol use. Results of Aim 2 indicated that, across groups, serum BDNF levels decreased in response to stress, but there were no main effects or interactions of BDNF genotype or FH group. However, in the Val66Met group, stress-related BDNF change (post- minus pre-stress) was related to age at first drink, such that earlier age of alcohol use was associated with a greater stress-related decrease in serum BDNF. This relationship was not present in the Val66Val group. Taken together, the results of these two aims suggest that in healthy young social drinkers, the association between the Val66Met SNP and alcohol use may be linked to stress vulnerability and behavioral risk factors (i.e., earlier initiation of alcohol use), which are known to be associated with the development of alcohol dependence.


    BIO: Shobhit Sharma received his MS in Biology from Texas State in Spring 2011. He entered Aquatic Resources Ph.D. program in Fall 2011. As an instructional assistant he has taught laboratory courses in Anatomy & Physiology and Clinical Lab Science. During his PhD he received grant from The Texas Research Society on Alcoholism (TRSA).


    Thesis Defense


    Grazing Influence on Selected Parameters of the Avian Community on a Texas Hill Country Ranch


    Joseph A. Jandle

                                                                                          
    Major Advisor: Dr. Thomas R. Simpson, Department of Biology, Texas State University             

    Committee Members: Dr. Michael R. J. Forstner, Department of Biology, Texas State University

    Dr. M. Clay Green, Department of Biology, Texas State University

                                                                                          

    Monday, March 28, 2016, 9:00 AM, Supple 153


    Many regionally declining prairie and shrubland birds breed in the Edwards Plateau ecoregion of Central Texas.  Additionally, Central Texas supports a winter resident bird community rich in ground foraging sparrow species.  Livestock grazing can have species specific and mixed results for local bird communities and other wildlife.  I examined the degree to which grazing influences bird foraging frequency and the overall bird community relative to herbaceous ground cover at Freeman Center, a 1,701 ha working cattle ranch in the Balcones Canyonlands subregion of the Edwards Plateau.  For one year, I conducted avian surveys and herbaceous ground cover surveys on two grazed and two ungrazed pastures using twenty, 100 meter fixed radius point count sites and twenty, 100 meter transects extending from each site.  I included a total of 383 line transect Daubenmire surveys, 135 point count surveys, and 184 avian walking transect surveys in various analyses.  I used GLMs to analyze herbaceous ground cover surveys in grazed and ungrazed sites.  I incorporated significant herbaceous predictors into GLMMs to analyze breeding and winter resident abundance, richness, diversity, and evenness.  I also included site as a random factor.  I built an additional GLMM to analyze avian winter ground foraging counts.  I identified a total of 138 avian species from Freeman Center between January 2014 and May 2015.  All breeding bird indices were significantly different between years.  Breeding bird richness positively correlated with forb cover (P = 0.003).  Breeding bird diversity was positively correlated with tallest green grass (P = 0.016) and forb cover (P = 0.007).  Except foraging counts, no winter resident indices were significantly correlated with herbaceous ground cover predictors.  Winter resident foraging counts were positively correlated with forb cover (P = 0.002).  Breeding and wintering bird abundance, richness, diversity, and ground foraging counts were higher in grazed sites than ungrazed sites.  Results suggest that moderate rotational grazing promotes forb production and native forbs are important for breeding and wintering birds in the Texas hill country.  Future study should determine herbaceous diversity and the dominant herbaceous plants in a study area.  Judgment deferred rotational grazing should be appropriate when ranch managers have the knowledge, experience, and prudence to make best-management decisions based on climate, rainfall, and sustainability.  A Multi-year study is necessary to assess long-term cattle use and the affects of climate and rainfall on the health and future of ranch operations and wildlife at Freeman Center.


    Bio: Joseph A. Jandle was born in San Marcos, Texas. He earned a B.S. from Texas State University in 2011 with a major in Wildlife Biology.  He entered the Wildlife Ecology Master’s program at Texas State University in 2014. He studies avian ecology with an emphasis on identification, vocalization, and rangeland species in Dr. Simpson’s lab.


    Thesis Defense


    Geochemical clues to groundwater sources of the Pedernales River


    Sarah J. (Saj) Zappitello


    Major Advisor: Dr. Benjamin Schwartz            

    Committee Members:  Dr. Thomas Hardy, Dr. Alan Groeger

    Wednesday, March 23, 1:00PM, Freeman Aquatic Building 130


    Interactions between aquifers and rivers are recognized as important components of the hydrologic system. Central Texas rivers and aquifers are especially well connected due to karstic carbonate geology where gaining and losing streams, springs, and caves are common. The Pedernales River is an important source of water for local communities, the city of Austin, and downstream water users of the Colorado River, to which it drains. The Pedernales River Basin is surrounded by rapidly developing areas with increasing water demands, but the majority of the watershed is developed only for agriculture. Identifying critical areas for water quality and quantity protection while the land is still relatively undeveloped creates an opportunity for proactive water resource protection. This study compares the geochemistry of waters from the main stem and tributaries to the Pedernales River, springs across the basin, wells screened in specific aquifers, and historic data. By conducting this study during baseflow conditions, the water sources are assumed to originate exclusively from groundwater, as opposed to runoff or soil interflow. Geospatial information was also evaluated for river gains and losses where measured, springs, and surface geology. Stable isotope ratios and principal component analysis highlight the importance of groundwater contributions to the river and indicate that evaporation is controlling the geochemical evolution of surface waters. Human impacts are also illustrated by spatial analysis of water geochemistry.


    Bio: Saj Zappitello is from Dripping Springs, Texas. She graduated from the University of Texas at Austin in 2006 with a B.S. in Hydrogeology and Environmental Geology. Saj is a professional geologist and an endangered karst invertebrate specialist, and she worked in environmental consulting on karst issues in the Edwards Aquifer before starting her Masters of Science in Aquatic Resources at Texas State University in the fall semester of 2014. She is an avid cave explorer and tuba player. Saj lives in south Austin with her husband, two ferrets, and ten chickens.


    Thesis Defense


    Inhibition of quorum signaling in Chromobacterium violaceum in the presence of cadmium, cobalt and nickel divalent cations


    Name: Starla Thornhill


    Major Advisor:   Dr. Robert JC McLean 

           

    Committee Members: Dr. Leticia Vega, Jacobs International (NASA JSC);   

                                    Dr. Kavita Kakirde, Texas State University

     

    Tuesday, March 22, 2016, 11 AM, Norris Room


    Bacteria are single celled organisms capable of acting as a single unit by sensing and responding to population density via a phenomenon called quorum signaling. Quorum signaling regulates a variety of phenotypes including biofilm formation and virulence factor production. In the soil bacterium Chromobacterium violaceum the virulence factor violacein results in a deep purple pigmentation and is one such regulated phenotype. Previously, a number of biological and organic molecules have been described as quorum signaling inhibitors, but to date no metal-based inhibitors have been identified. In this study, we show that quorum sensing is inhibited in C. violaceum when in the presence of sub-lethal concentrations of cadmium based salts. Cobalt and nickel salts have also been indicated as inhibitors in other gram negative species. Inhibitory effects of cadmium divalent cations on C. violaceum were shown in biofilm formation, pigmentation and virulence factor production, as well as transcript levels for genes involved in these processes. This study represents the first description of heavy metal based quorum sensing inhibition in C. violaceum.


     Starla Thornhill graduated from Texas State University with a B.S. in Microbiology in May 2014. Her research interest is in bacterial growth in the microgravity environment, and she has spent time at NASA Johnson Space Center training in use of microgravity simulating bioreactors. 


    Dissertation Proposal Defense


    The Arabidopsis Mediator Complex Subunit 9, a MORC1 interacting protein, is a positive regulator of plant immunity


    Ji-Chul Nam


    Major Advisor: Dr. Hong-Gu Kang, Department of Biology, Texas State University             

    Committee Members: Dr. Nihal Dharmasiri, Department of Biology, Texas State University

    Dr. Sunethra Dharmasiri, Department of Biology, Texas State University

    Dr. Walter Gassmann, Division of Plant Sciences, University of Missouri

    Dr. Keiko Yoshioka, Department of Cell & Systems Biology, University of Toronto

    Tuesday, March 1, 2016, 2:00 pm, 209 Undergraduate Academic Center

    Arabidopsis thaliana MORC1 (Microrchidia), also known as CRT1, is an ATPase protein that is required for multiple levels of plant immunity including effector-triggered immunity (ETI), PAMP (pathogen-associated molecular pattern)-triggered immunity (PTI), basal resistance, non-host resistance, and systemic acquired resistance. Consistent with its role in ETI and PTI, MORC1 physically interacts with 11 resistance proteins and the PAMP-recognition receptor FLS2. We employed yeast two-hybrid to assess a protein-interaction profile of MORC1 and identified 14 MORC1-interacting proteins (MIPs). To characterize the role of MIPs in plant immunity, we obtained T-DNA insertion lines for some MIPs and generated combined mutants with morc1/morc2. Five out of eight mip mutants tested exhibited decreased resistance against Pseudomonas syringae, suggesting that these MIPs function in plant immunity. For instance, mip13 displayed compromised resistance to P. syringae while overexpression of MIP13 conferred enhanced antibacterial resistance. Interestingly, addition of the morc1/2 mutation restored resistance to P. syringae in mip13, suggesting a complicated interaction between MIP13 and MORC1/2 in plant immunity. MIP13 encodes MED9, a component in plant RNA polymerase II mediator complex and likely functions in the transcriptional induction of defense genes. Thus, we are currently assessing the transcriptional induction of selected defense genes in MIP13 altered backgrounds in conjunction with morc1/2 to learn how MIP13 and MORC1/2 interplay in plant defense responses.


    Bio: Nam Ji-Chul was born in Seoul, South Korea. He earned a B.S. from the University of Missouri in 2010 with a major in Biological Sciences. He earned a M.S. from the University of Missouri in 2013 in Plant Sciences from Dr. Gassmann. He entered the Aquatic Resources Ph.D. program at Texas State University in 2013. He studies molecular plant immunity with an emphasis on the transcriptional control of disease resistance genes in Dr. Kang’s lab.

     


    Dissertation Proposal Defense


    Natural History, Demographic Parameter Estimates, and Survey Techniques for Federally Threatened Jollyville Plateau Salamanders (Eurycea tonkawae)

     


    Zachary C. Adcock


    Major Advisor: Dr. Michael Forstner, Department of Biology, Texas State University             

    Committee Members: Dr. David Rodriguez, Department of Biology, Texas State University

    Dr. Benjamin Schwartz, Department of Biology, Texas State University

    Dr. Benjamin Pierce, Department of Biology, Southwestern University

    Dr. James Nichols, U.S. Geological Survey

    Tuesday, January 19, 2016, 3:00 pm Norris Room


    The central Texas Eurycea salamanders are of high conservation concern because of their extreme level of endemism, small ranges, and the rapid urbanization of the greater Austin and San Antonio areas. Seven of the 13 currently recognized species are listed as either threatened or endangered by the U.S. Fish and Wildlife Service (USFWS), and three additional species are listed as threatened or endangered by the Texas Parks and Wildlife Department (TPWD). Eurycea tonkawae was federally listed as threatened in 2013, and despite the increased attention from the listing process, few publications exist that advise conservation decisions for this taxon. The USFWS relied heavily on unpublished data for the listing decision and for establishing critical habitat units. Effective design and implementation of conservation policy is not possible without adequate natural history knowledge of the target species. In this dissertation, I intend to address several issues important to the conservation of E. tonkawae, including: 1) delineating the full extent of occupied surface habitat, 2) identifying small-scale environmental variables that influence presence (microhabitat parameters), 3) describing annual ecology, 4) estimating demographic parameters (e.g., abundance, survival), and 5) investigating environmental DNA (eDNA) as a survey technique. This work will contribute to informed conservation policy and management decisions for the recovery of Eurycea tonkawae.


    Bio: Zach Adcock was born in Andrews, TX and raised in Cedar Hill, TX. He earned a B.S. from the University of Tampa in 2004 with a double major in Biology and Environmental Science and a double minor in Marine Biology and Chemistry. He earned a M.S. from the University of South Florida in 2012 in Integrative Biology from Drs. Henry Mushinsky and Earl McCoy’s lab. He worked as a wildlife and wetland consultant in Florida for 10 years concurrent with and in-between the two degrees. He entered the Aquatic Resources Ph.D. program at Texas State University in 2012, in Dr. Michael Forstner’s lab, to continue work on the conservation of endangered and threatened wildlife. His fiancée, Michelle Curtis, is in the Wildlife Ecology program at Texas State University and they have one son, Davis, of whom they are very proud.


  • Proposal Defense


    Characterization of chromatin-remodeling factors in plant immunity


    April Bonnard


    Major Advisor: Dr. Hong-Gu Kang            

    Committee Members: Dr. Nihal Dharmasiri & Dr. Suni Dharmasiri

    Tuesday, December 8, 2015, 2:00PM, Norris Room, Supple Building


    Abstract: Plants have evolved a complex immune system against various pathogens, part of which involves the function of resistance (R) proteins in detecting the presence of secreted effector molecules from pathogens. This detection then leads to a robust immune response by implementing large-scale modifications in chromatin accessibility, thus leading to transcriptional reprogramming. MORC1 is a protein that interacts with several of these R-proteins and is required to maintain optimum levels of immunity in Arabidopsis thaliana. It is speculated that MORC1 is a putative chromatin-remodeling factor as it has been shown to exhibit ATPase and endonuclease activity and that a subpopulation localizes to the nucleus after pathogen infection. In this research, we aim to characterize the interaction of MORC1 with several other chromatin-remodeling factors, including ACT1, ARP4, SWC2, SWC5, SWC6, SUF3, PIE1, RVB1, and YAF9, which together comprise many of the components of the SWR1-like complex in Arabidopsis to better understand the role of MORC1 as well as the link between chromatin-remodeling and plant immunity.


    Bio: April Bonnard graduated from Texas State University in 2014 earning a B.S. in Biology with a minor in Biochemistry. She is now pursuing her M.S. in Biology at Texas State University where she is studying the relationship between chromatin-remodeling and plant immunity. During her time in the M.S. program, she became a member of the Alpha Chi National College Honor Society and participated in the 20th Annual Department of Biology Colloquium, where she received an award for the best talk at the M.S. level.


    Proposal Defense


    AN ANALYSIS OF THE EFFECTS OF SUSPENDED SEDIMENT AND PHOTOSYNTHETICALLY ACTIVE RADIATION (PAR) ON THE VEGETATIVE GROWTH OF TEXAS WILD RICE (ZIZANIA TEXANA)


    Michele Crawford-Reynolds


    Major Advisor: Dr. Thom Hardy, Department of Biology, Texas State University    

             

    Committee Members: Dr. Paula Williamson, Department of Biology, Texas State University

    Dr. Weston Nowlin, Department of Biology, Texas State University                                                

    Dr. David Lemke, Department of Biology, Texas State University

    Dr. Tina Cade, Department of Agriculture, Texas State University

    Dr. Robert Doyle, Department of Biology, Baylor University         

    Thursday, December 3, 2015, 9:00 AM, Freeman Aquatic Building, Room 130


     Texas wild rice (TWR), Zizania texana, is a submerged macrophyte with a single known population existing in the upper reaches of the San Marcos River.  Historically, this rare aquatic grass was in greater abundance than is observed today. First listed as a federally endangered species by the U.S. Fish and Wildlife Service in 1978 priority has since then been placed on the recovery and sustainability of TWR.  Anthropogenic factors have been suggested to continue to present challenges for the re-introduction and maintenance of TWR. Previous research has focused on habitat suitability preferences for TWR with research still lacking in understanding all the factors that may limit its potential to recover to historical levels. Suspended sediment induced turbidity due to contact recreational use of the river is one such anthropogenic factor suggested to be problematic. Turbidity has been correlated with causing a decrease in the availability of photosynthetically active radiation (PAR) in aquatic systems. The goal of this study is to evaluate the impact suspended sediment induced turbidity and subsequent reduction in PAR has on the vegetative growth and biomass productivity of TWR.  The experimental design will involve both in situ and ex situ observations, seasonal aspects (temporal) and recreational use (low and high). Identifying the impact recreational induced turbidity has on the vegetative growth of TWR may provide additional information useful in future conservation and restoration effort.


     Michele Crawford-Reynolds graduated from University of The Incarnate Word in 1991 earning a bachelor’s in biology. She later earned a master’s degree from UIW in biology (’93) and in education from Sul Ross University (’98). She has taught at a community college in the biology department since 1995. She has two children, a daughter majoring in biology at Texas A&M University in College Station and a son majoring in psychology attending Austin Community College.


    Proposal Defense


    AN ANALYSIS OF THE EFFECTS OF SUSPENDED SEDIMENT AND PHOTOSYNTHETICALLY ACTIVE RADIATION (PAR) ON THE VEGETATIVE GROWTH OF TEXAS WILD RICE (ZIZANIA TEXANA)

     


    Michele Crawford-Reynolds


    Major Advisor: Dr. Thom Hardy, Department of Biology, Texas State University              

    Committee Members: Dr. Paula Williamson, Department of Biology, Texas State University

    Dr. Weston Nowlin, Department of Biology, Texas State University

    Dr. David Lemke, Department of Biology, Texas State University

    Dr. Tina Cade, Department of Agriculture, Texas State University

    Dr. Robert Doyle, Department of Biology, Baylor University

     

    Thursday, November 19, 2015, 8:30 AM, Freeman Aquatic Building, Room 130


     Texas wild rice (TWR), Zizania texana, is a submerged macrophyte with a single known population existing in the upper reaches of the San Marcos River.  Historically, this rare aquatic grass was in greater abundance than is observed today. First listed as a federally endangered species by the U.S. Fish and Wildlife Service in 1978 priority has since then been placed on the recovery and sustainability of TWR.  Anthropogenic factors have been suggested to continue to present challenges for the re-introduction and maintenance of TWR. Previous research has focused on habitat suitability preferences for TWR with research still lacking in understanding all the factors that may limit its potential to recover to historical levels. Suspended sediment induced turbidity due to contact recreational use of the river is one such anthropogenic factor suggested to be problematic. Turbidity has been correlated with causing a decrease in the availability of photosynthetically active radiation (PAR) in aquatic systems. The goal of this study is to evaluate the impact suspended sediment induced turbidity and subsequent reduction in PAR has on the vegetative growth and biomass productivity of TWR.  The experimental design will involve both in situ and ex situ observations, seasonal aspects (temporal) and recreational use (low and high). Identifying the impact recreational induced turbidity has on the vegetative growth of TWR may provide additional information useful in future conservation and restoration effort.


    Michele Crawford-Reynolds graduated from University of The Incarnate Word in 1991 earning a bachelor’s in biology. She later earned a master’s degree from UIW in biology (’93) and in education from Sul Ross University (’98). She has taught at a community college in the biology department since 1995. She has two children, a daughter majoring in biology at Texas A&M University in College Station and a son majoring in psychology attending Austin Community College.

     


    Thesis Defense

     

    CHARACTERIZATION OF A MAJOR FACILITATOR SUPERFAMILY TRANSPORTER PROTEIN IN ARABIDOPSIS


    Damian T. Raymond


    Major Advisor: Dr. Nihal Dharmasiri     

    Committee Members: Dr. Sunethra Dharmasiri and Dr. Hong-Gu Kang

     

    Monday, Nov 9, 2015,  8:30 am in Supple 257


    The Major facilitator superfamily (MFS) transporter proteins regulate solute homeostasis across membranes in both prokaryotes and eukaryotes. Recently we isolated several mutant alleles of Arabidopsis PIC30, which encodes an MFS transporter protein that transports nitrate (NO3-) and synthetic auxin, picloram. Arabidopsis genome also consists of a gene, PIC30H (PIC30 homolog), which shows higher sequence homology to PIC30. In silico analysis indicate that both PIC30 and PIC30H consist of an MSF domain and a Noduline like (NOD) domain. Therefore, we hypothesized that PIC30H may function redundantly with PIC30. Using genetic and biochemical approaches we found that PIC30H localizes to plasmamembrane similar to PIC30. Nevertheless, tissue specific expression of these two genes indicates reasonable differences in spatial expression.  Furthermore, overexpression of PIC30H in pic30 did not rescue the picloram resistant root growth of pic30 suggesting that these two genes may not function redundantly. Arabidopsis mutants of both PIC30 (pic30) and PIC30H (pic30HKO) were resistant NO3- analog ClO3- suggesting both PIC30 and PIC30H transport NO3- inwardly. Interestingly, dark-induced hypocotyl growth of pic30HKO was hypersensitive to picloram while the hypocotyls of pic30 mutant was resistant when compared with wild type suggesting that PIC30 and PIC30H may transport picloram in an opposite direction. Taken together these results indicate that while some transport functions of PIC30 and PIC30H are similar, they may also have different transporter functions despite their sequence similarity.


    Bio:  Damian T. Raymond graduated from University of Peradeniya – Sri Lanka in 2011 earning a B.S. in Botany with a minor in Chemistry.  In 2013, he began pursuing a M.S. in Biology at Texas State University, characterizing a putative picloram transporter protein in Arabidopsis.


    Thesis Defense


    Rumenreticulum - Liver Masses Relationship in White-tailed deer (Odocoileus virginianus) differ between males and females


    Gayatri Bhaskar


    Major Advisor: Dr. Floyd. W. Weckerly            

    Committee Members:  Dr. Thomas R. Simpson, Dr. M. Clay Green.

    Wednesday, November 11th, 8:00AM, Supple Science Building 153


    Relationships between organ masses probably influence energy demands in mammals. Previous studies have estimated allometric relationships between body mass and organ masses in white-tailed deer. To my knowledge, however, there has been no investigation into the relationship between rumen-reticulum organ mass and liver mass in any ungulate. Furthermore, energetically demanding life history events like lactation in females and mating in males should affect organ workloads. Understanding the co-dependent relationships of these organs could be insightful to understanding the energy conservation strategy of white-tailed deer. I examined relationships between rumen-reticulum organ and liver masses in white-tailed deer to see if relationships differed between females and males during and two months before the mating season. I collected 151 white-tailed deer (68 males and 83 females) from Kerr pens, Central Texas, and a private ranch in South Texas (SOTX). Deer from the Kerr pens were obtained during the peak of the mating season, whereas deer from SOTX were collected two months prior to the mating season. All females had also given birth to young in the previous spring or summer. There was a positive relationship between masses of the rumen-reticulum organ and liver at both study areas. However, this relationship differed between males and females. In comparison to females, males exhibited heavier livers in relation to rumen-reticulum organ masses at both study areas. These findings might be useful to understanding physiological changes during energetically demanding periods in male and female white-tailed deer.


    Bio: Gayatri Bhaskar is from Bangalore, India. She attended Western Kentucky University at Bowling Green, KY for her B.S in Biology. Gayatri began the Masters of Science in Wildlife Ecology at Texas State University in spring semester, 2014. While at Texas State, she presented a paper on “Birth mass scaling in Elk (Cervus elaphus)” at the 51st Texas Chapter of the Wildlife Society annual meeting, Corpus Christi, Texas. During the summer of 2015, she worked as an intern for Texas Parks and Wildlife at Kerr Wildlife Management Area, Hunt, TX.


    Thesis Defense

     

    Urbanization and Stress Response of Texas Eurycea Salamanders


     Name: Megan J. Mondelli


    Major Advisor: Caitlin R. Gabor, Department of Biology, Texas State University 

                

    Committee Members: Chris Nice, Department of Biology, Texas State University

    Andrew Gluesenkamp, Texas Parks & Wildlife

    Nathan Bendik, Watershed Department, City of Austin

     

    November 6, 2015, 8AM, Norris Room


    Amphibians worldwide are rapidly declining. Successful conservation strategies should consider the physiological response of an organism to its environment using stress hormones. Glucocorticoid (CG) hormones are a particularly useful class of biomarkers that effectively measure stress. The primary GC stress hormone in amphibians is corticosterone (CORT). Short-term increases in CORT (i.e., acute stress) are adaptive during stressful events because CORT mediate metabolic and immune function. However, chronic stress can be harmful to the overall health of an organism and can lead to dysregulation of the hypothalamic-pituitary-interrenal (HPI, for amphibians) axis leaving the organism susceptible to metabolic and immune problems. Chronic stress is also associated with suppressed reproductive hormones such as testosterone and estradiol. Anthropogenic and environmental factors such as seasonal changes, urbanization (modification, pollution) and storms have been shown to affect stress and reproductive hormones. Here, I studied how these factors affect the stress of two federally threatened species of Texas Eurycea salamanders that are fully aquatic. I conducted two projects, the first of which measured stress levels of E. tonkawae, Jollyville Plateau salamander, in urban and rural streams across seasons. I also examined the correlation between stress, sex steroids and activity levels of salamanders in urban and rural streams. My second project investigated the effects of storm water runoff on stress of E. nana, San Marcos salamander. I found that CORT in E. tonkawae is highest in summer but did not vary based on stream type. Activity in E. tonkawae varied by population; one urban stream showed a positive correlation between activity and CORT while but this was not the case in the other populations. However, urbanization did not affect activity level. Additionally, my research shows a significant effect of storm runoff water on testosterone, but not CORT in E. nana. In conclusion, my research shows that CORT changes with season and should be considered when testing other questions stress response. Additionally, it is possible that storm water does not affect the stress of salamanders, but some other factor associated with storm events might be stressing these salamanders. Further research is needed to tease out what factors maybe stressful.


    Bio:  Megan J. Mondelli graduated from Rowan University (New Jersey) in 2013 earning a B.S. in Biological Sciences. During her undergraduate degree in 2012, she received a National Science Foundation funded REU position to explore population distributions and prey type of Plethodontid salamanders in New Hampshire. After, graduating, she worked for Rutgers University at Haskin Shellfish Research Laboratory participating in an oyster stock assessment survey for the Delaware Bay. In 2014, Megan began pursuing a M.S. in Population and Conservation Biology at Texas State University, studying how urbanization affects the seasonal variation in hormones and behavior and how runoff from storms affects hormones of Texas Eurycea salamanders.


    Thesis Defense


    AN EXAMINATION OF GENE FLOW AMONG DISTINCT MANAGEMENT UNITS

    OF THE REDDISH EGRET (Egretta rufescens)


    Golya Shahrokhi


    Major Advisor: Dr. M. Clay Green           

    Committee Members:  Dr. David Rodriguez, Dr. Bart M. Ballard

    Friday, October 30, 2015, 10:00 AM, Supple Building, Room 257


    Reddish Egret (Egretta rufescens) is one of the least studied herons in North America. This dimorphic bird ranges from Baja California to Bahamas, north to Texas and Louisiana and southwards to Central America and northern part of South America. For this study we examined gene flow and genetic diversity among populations across the range of the species. We specifically tested the hypothesized distinct management units (Western, Central, Eastern) based on geographic distribution and the findings of Hill et al. (2012). We collected blood and feather samples from nestlings (n = 145) of 8 populations (Baja California, Chiapas, Yucatan, Tamaulipas, Texas, Louisiana, Florida and the Bahamas). We extracted DNA from collected samples and used 10 microsatellite markers and one mtDNA (control region) to estimate deviations from Hardy-Weinburg equilibrium, genetic differentiation, structure and gene flow. In all analysis we had more differentiations among groups and regions (Fst = 0.21) than among populations within groups (Fst = 0.09). Our results revealed three primary breeding concentration centers, one in each of the management units (Baja California for Western, Chiapas for Central, and Bahamas for Eastern) providing further support for the established management units. We found greater differentiation between populations in our mtDNA analysis suggesting less movement across populations and management units and greater philopatry in females in comparison to males. Differences in movement patterns between males and females is also supported by recent banding and telemetry data. Lastly, gene flow between the Baja California population and the remainder of species’ populations is weak whereas we detected weak to moderate gene flow between populations in Central and Eastern management units


    Bio: Golya Shahrokhi received her Bachelor’s degree at Shahid Beheshti University (National University of Iran) in Biology with a minor in Zoology from Iran in 2012. She enrolled in the Wildlife Ecology Master program at Texas State University - San Marcos in 2013 and has started to work with Dr. M. Clay Green since then.  While her studies at Texas State, she won the Kushlan Research Award from Waterbird Society and Texas State University Graduate College Thesis Research Support Fellowship. Her poster, also, won the best student poster at Waterbird Society meeting in Bar Harbor, Maine in August 2015.


    Thesis Defense

    Characterization of an IBR5 interacting protein, ARA2 in Arabidopsis auxin response


    Prabesh Ghimire

    Major Advisor: Dr. Nihal Dharmasiri, Department of Biology, Texas State University         

    Committee Members:  Dr. Hong-Gu Kang, Department of Biology, Texas State University

                                     Dr. Sunethra Dharmasiri, Department of Biology, Texas State University

     

    October 29, 2015,  2.00 pm in Supple 257


             Auxin controls plant growth and development through both genomic and non-genomic processes. Genomic processes are regulated through the degradation of a group of transcriptional repressors called Aux/IAAs. Recent studies indicate that IBR5 (Indole-3-butyric acid response5), a dual specificity phosphatase, also regulates degradation of Aux/IAAs through an unknown mechanism. To better understand how IBR5 regulates plant auxin response, we recently carried out a yeast two hybrid screen to identify IBR5 interacting proteins. ARA2 was isolated as one of the putative IBR5 interacting proteins. ARA2, which is a small GTP binding protein, belongs to Ras super family of proteins that play essential roles in the intracellular transport pathways of yeast, mammalian cells, as well as in plant responses to various environmental stimuli. Several other small GTPases such as ROP2 and ROP6 are also known to be involved in plant auxin responses suggesting that small GTPases are integral components of auxin signaling. Thus, it was hypothesized that ARA2 play a role in plant auxin responses through interaction with IBR5. Results presented here show that ARA2 physically interacts with IBR5 both in-vitro and in vivo. This interaction occurs through the catalytic domain of IBR5. Interestingly, Aux/IAA degradation in loss-of-function ara2 mutant is affected suggesting that ARA2 may be a positive regulator of auxin responses. Nevertheless, ara2 mutant does not any show altered auxin related physiological responses probably due to genetic redundancy. However, characterization of ara2/ibr5-1 double mutant reveals that ara2 mutation functions as a mild enhancer of ibr5-1 especially in stress responses suggesting that ARA2 together with IBR5 may function in modulating the auxin responses during environmental stress.


    Bio: Prabesh Ghimire was raised in Kathmandu, Nepal and received his BS degree in Biotechnology from Purbanchal University, Kathmandu in December 2011. Then he joined the Department of Biology, Texas State University to follow graduate studies in 2013. During his MS program, he worked both as a research assistant and an instructional assistant. In 2014, he was awarded the best poster presentation at the Biology Colloquium.


    Thesis Defense

     

    HABITAT SUITABILITY AND AVAILABILITY FOR RAINBOW TROUT ONCORYNCHUS MYKISS IN THE CANYON RESERVOIR TAILRACE AND EVALUATION OF SIDE SCAN SONAR FOR HABITAT MAPPING IN A SEMI-WADABLE RIVER


    Greg A. Cummings


    Major Advisor: Dr. Thomas B. Hardy     

    Committee Members: Dr. Timothy H. Bonner, Dr. Adam J. Kaeser

    October 27, 2:00 PM, The Meadows Center for Water and the Environment, (SLH 107)


    Rainbow Trout Oncorhynchus Mykiss are typically stocked in tailraces across the southeastern United States to mitigate fish habitat and assemblage alterations caused by large impoundments.  Hypolimnetic discharges from Canyon Reservoir have created conditions suitable for a coldwater tailrace fishery and Rainbow Trout have been stocked there since 1966.  This study examined changes in suitability and availability of Rainbow Trout habitat with discharge rate to provide flow and stream restoration recommendations for the Canyon Reservoir tailrace.  Physical habitat modeling incorporated habitat suitability information for three life stages of trout coupled with hydraulic modeling to assess habitat quality and quantity at various flow rates.  Habitat mapping included traditional surveying, remote sensing, bathymetric mapping, and side scan sonar.  Side scan sonar was evaluated for efficiency and applicability to semi-wadable rivers.  Results indicate the tailrace is spawning limited and temperature, not habitat, is the primary limiting factor for adult trout.  Modified flow rates and specific stream restoration measures could increase adult trout abundance and assist put-grow-and-take strategies in the upper portion of the tailrace.  Side scan sonar provided efficient mapping of non-wadable sections of the study area.  However, there were limitations related to water level, access, navigability, positional accuracy, and post-processing.  Trial runs, training, map accuracy assessments, and further development with instruments and post-processing will improve this method in similar scenarios.


    Bio:  Greg A. Cummings graduated from Oklahoma State University in 2003 earning a B.S. in Wildlife and Fisheries Ecology with a minor in Geography.  After graduating, he interned with a North Carolina State University graduate study investigating Striped Bass diet in the Albemarle Sound estuary.  Since 2004, he has worked for the Inland Fisheries Division of Texas Parks and Wildlife, managing public fisheries in Central Texas.  In 2010, he began pursuing a M.S. in Aquatic Resources at Texas State University, studying habitat mapping techniques and stream modeling.


    Thesis Defense

     

    Ionic Requirements of Blue Crab, Callinectes Sapidus, in Environments Containing Low Concentrations of Total Dissolved Solids


    Duane A Friedman


    Major Advisor: Dr. Joseph R. Tomasso                                 

    Committee Members: Dr. Weston H Nowlin, Dr. Benjamin Schwartz

     

    Friday, October 23, 2:00 pm, Freeman Aquatic Building, Room 130


    The goal of this study was to develop an ionic environment containing 1 g/L total dissolved solids (TDS) that would support the survival and growth of juvenile blue crabs (designated a “mixed-ion solution”). The 1 g/L TDS level was selected in order to minimize the cost of preparing ponds and to potentially reduce the need for effluent permitting in inland areas. The general approach was to provide selected ions in approximate concentrations found in 1 g/L dilute seawater.

    In a series of three-week exposures beginning with ~20 mm carapace-width crabs, we found:

    1. Growth in artificial sea-salt treatments of 1, 2, 4, and 8 g/L TDS averaged 76% ± 20.2% (mean ± SD) and was not significantly affected by treatments. The number of molts, feed intake and modified feed conversion ratio were not significantly affected by treatments.
    2. Growth during exposure to 1 g/L sea-salt, 0.5 g/L sea-salt + 0.5 g/L mixed-ions or 1 g/L mixed-ions averaged 41% ± 0.49% and was not significantly affected by treatment. Although not quantified, some exoskeletons in the mixed-ion treatment appeared soft and off-colored, leading us to investigate the need for environmental strontium in the next experiment.
    3. Average survival during the 21-d exposure of 1 g/L mixed-ions with 0, 1 and 2 mg/L strontium was 89% ± 12.7% and did not differ significantly across treatments. Growth across treatments averaged 40% ± 25.3% and was not significantly affected by treatment.
    4. All crabs in the 1 g/L mixed-ion environment (with 1 mg/L strontium) survived the 21-d exposure to temperatures of 26, 29, and 32oC. Growth in all treatments averaged 71% ± 12.1% and was not significantly affected by treatments. Due to two previous, failed experiments, 133 mg/L of sodium bicarbonate was substituted for 133 mg/L of sodium chloride to maintain pH levels above 7.5.

    These results indicate that blue crabs can survive and grow in 1 g/L mixed-ion solution.


    Bio: Duane Friedman was born in Philadelphia, Pennsylvania, grew up in the Naval life-style, living along most of the Eastern coastline. Following high school in West Deptford, New Jersey, he relocated to Oceanville, New Jersey, and entered the workforce. Eventually, his aspirations of working in the fisheries industry got the best of him and he became a commercial blue crab fisherman/aquaculturist. This led to an undergraduate degree, earning a B.S. in Marine Biology from the Richard Stockton College of New Jersey in Galloway, New Jersey. As part of his B.S., Duane completed an internship at the MOTE Marine Laboratory in Sarasota, Florida, culturing snook, pompano and amberjack. His journey to complete his life-long goal of becoming a Fish Biologist, Duane has had the opportunity since June of 2015, to work as a Biological Fisheries Student/Trainee at SMARC. At SMARC, he served as a caretaker in the endangered and threatened devil river minnow refugium, successfully completing production of 2800 F1 offspring. Following graduation Duane hopes to pursue a Doctorate degree and continue his career in aquaculture research for the federal government.


    Thesis Defense


    SPRING FLOW AND HABITAT-MEDIATED EFFECTS ON REPRODUCTIVE EFFORT OF THE FOUNTAIN DARTER


    Harlan T. Nichols


    Major Advisor:  Dr. Timothy H. Bonner           

    Committee Members:  Dr. Kenneth G. Ostrand (USFWS), Dr. Joseph A. Veech

     

    Thursday, October 22, 10:00am, Freeman Aquatic Building, Room 130


      Reductions in Edwards Aquifer spring flows are hypothesized to reduce reproductive effort of spring-associated fishes.  Purposes of this study were to test relationships among spring flow, associated habitat changes, and reproductive effort of the federally-listed Fountain Darter Etheostoma fonticola, a spring-associated fish inhabiting Comal and San Marcos rivers of central Texas. Study objectives were to quantify annual reproductive effort (i.e., ovarian stages, gonadosomatic index, and batch fecundity) across low to high flow gradients and aquatic habitats using natural and anthropogenically-altered stream reaches (N = 4) within the Comal and San Marcos rivers to represent in situ flow reductions.   Contrary to previous studies reporting year-round spawning, annual reproductive cycle of the Fountain Darter consisted of an optimal reproductive season (January through April), and tailing reproductive season (May through August), lack of spawning in September, and a leading reproductive season (October through December).  Among reproductive seasons, stages of ovarian condition, gonadosomatic indices, and batch fecundity generally were not different along a flow gradient or among habitats, though two exceptions were noted.  Gonadosomatic index and batch fecundity were greater (P < 0.05) at the higher flow environment (3.6 m3/s) during optimum reproductive season and greater (P < 0.05) at the lowest flow environment (0.01 m3/s) during the leading reproductive season.  Collectively, seasonality of reproductive effort was similar to sister taxa (Cypress Darter E. proeliare, Least Darter E. microperca), though protracted, and reproductive effort was not related consistently to flow environment observed during the study period.  However, other measures of reproductive effort (e.g., numbers of larvae hatched, survival of larvae through recruitment age) are necessary to quantify in order to assess the relationship among Fountain Darter viability and flow environments. 


    Bio:  Harlan T. Nichols graduated from Texas State University in 2013 with a B.S. in Aquatic Biology. During his time as an undergraduate he published research while working as an assistant for several other projects. He is currently working toward a M.S. in Aquatic Resources.


    Thesis Defense


    TESTING OF TROPHIC CASCADE WITHIN A HEADWATER SPRING COMMUNITY: IMPLICATIONS FOR WATER QUANTITY MANAGEMENT


    Myranda K. Clark


    Major Advisor:  Dr. Timothy H. Bonner           

    Committee Members:  Dr. Kenneth G. Ostrand (USFWS), Dr. Joseph A. Veech

     

    Wednesday, October 14, 1:00pm, Freeman Aquatic Building, Room 130

     


      A management strategy adopted to protect a federally-listed Fountain Darter Etheostoma fonticola during low flow conditions is the removal of a piscine carnivore Largemouth Bass Micropterus salmoides.  However, headwater spring communities with benthic Fountain Darters include another potential predator (Red Swamp Crayfish Procambarus clarkii).  Removal of a top predator, which consumes both benthic fish and crayfish, can produce a cascading effect and unintentionally increase rates of consumption on the Fountain Darter by removing top-down regulation of crayfish communities.  The purpose of this study was to test for cascading effects of benthic fish predation by quantifying number of Fountain Darters consumed by crayfish, bass, and combined crayfish and bass within vegetated and non-vegetated holding tanks.  Three water temperature trials were conducted to mimic low-flow winter temperatures (18°C), average spring-flow temperatures (22°C) and low-flow summer temperatures (27°C).  Among temperature trials, bass and crayfish and bass treatment levels consumed about equal numbers (P > 0.05) of Fountain Darters, whereas crayfish consumed the fewest number (P < 0.05) of Fountain Darters, except at 22°C.  Numbers of Fountain Darters consumed were unrelated to presences or absence of vegetation.  Collectively, study results were not consistent with cascading effects but rather with additive model of prey consumption.  As such, predator removal appears to be a viable option in reducing abnormal forms of mortality on benthic fishes during anthropogenically-induced periods of low flow, but removal efforts might create additional cascading effects.  Therefore, removal efforts should be monitored to further assess efficacy of the management strategy.


    Bio:  Myranda Clark received her Bachelor’s degree at Missouri State University in Springfield, MO, majoring in Wildlife Biology.  Throughout her undergraduate career, she interned for the Heartland Inventory and Monitoring Network of the National Park Service.  Upon completion of her Bachelor’s, she moved to San Marcos, Texas to pursue her education in Aquatic Biology under the direction of Dr. Tim Bonner.  As a full-time graduate student, she continued research in fish ecology, taught various labs including Ichthyology and served as president of the Aquatic Biology Society.


    Thesis Defense

    The prevalence of Trypanosoma cruzi, the causal agent of Chagas Disease, in rodent populations in Texas


    Adriana Aleman

    Major Advisor: Dr. Dittmar Hahn

    Committee Members: Dr. Michael Forstner, Dr. Ivan Castro-Arellano, and Dr. Hardin Rahe

    August 6, 2015, 3:00 pm, Supple 257


    Trypansoma cruzi is the parasite that causes Chagas disease, which affects over 8 million people in at least twenty-one countries in Central and South America. While Chagas disease has been recognized as a significant health threat to the 28 million people living in Central America, it has not been considered a significant threat to the people in the United States. Since rodents are one of the reservoir hosts for T. cruzi and abundant close to human housing, detections of T. cruzi in rodents provide a good approximation of the prevalence of Chagas disease and the potential threat to human health. The purpose of this study was to determine the incidence of rodents infected with T. cruzi in five geographical regions across Texas. T. cruzi was detected by real-time quantitative PCR (qPCR) in DNA extracted from heart tissue of rodents and detection assessed as a function of location, time of the season, and of rodent species. Of approximately six hundred samples analyzed, eight samples representing 6 rodent species were shown to be infected with T. cruzi, all from the most southern geographical region. The data indicate that rodent populations in selected regions of Texas are infected with T. cruzi. Further studies should be conducted to determine if other animal populations in the regions of Texas with rodent populations infected with T. cruzi may also be positive for the organism.


    Bio:  Adriana was born and raised in Dallas, TX. She received her Bachelor’s degree in Animal Science with emphasis in Pre-Veterinarian in May 2013 from Texas A&M University-Commerce in Commerce, TX. She started her Master’s program in Biology at Texas State University in August 2013, and has been working as a graduate research assistant. While working on her M.S., she had the opportunity to be part of a two week “study abroad” program in Costa Rica. Her research was funded by the United States Department of Agriculture.


  • Thesis Defense

     

    Effects of Temperature and Nitrogenous Wastes on Survival and Growth of the Barton Springs Salamander Eurycea sosorum


    Justin C. Crow


    Major Advisor: Dr. Joseph R. Tomasso                                 

    Committee Members: Dr. Michael R. J. Forstner, Dr. Kenneth G. Ostrand (USFWS)

    Thursday, August 06, 11:00 am, Freeman Aquatic Building, Room 130


    The Barton Springs Salamander (BSS), Eurycea sosorum, is a federally endangered obligate aquatic salamander found only in a few spring outflows located in a highly urbanized recreational area of Austin, Texas. The purpose of this study was to gain essential information regarding the physiological response of the BSS to thermal manipulations and three common aquatic nitrogenous toxins (ammonia, nitrite, and nitrate). All salamanders used in this study were produced at the San Marcos Aquatic Resource Center (SMARC, U.S. Fish and Wildlife Service) in San Marcos, Texas as part of a captive breeding program. To examine thermal stressors, salamanders were subjected to a nominal temperature increase of 0.5°C/day until a loss-of-righting response (LRR) was observed. Additionally, salamander growth was assessed following a 69 day trial in which young salamanders were reared at five different temperature treatments (nominal 15, 18, 21, 24 and 27°C). The cumulative ET50 of the LRR observed in the BSS was 32.6 ± 0.2°C (mean ± SD). The optimal temperature for growth of the BSS for weight and total length was estimated to be 19.0°C and 18.5°C, respectively. To investigate the effects of nitrogenous wastes on the BSS, ninety-six hour median-lethal concentration (96-hour LC50) trials were conducted for un-ionized ammonia-N (UIA-N), nitrite-N, and nitrate-N. The 96-hour LC50 of UIA-N, nitrite-N, and nitrate-N to the BSS was 2.1 ± 0.19 mg/L, 27.7 ± 0.72 mg/L, and 851.1 ± 49.21 mg/L, respectively. These results will aid in the conservation, management, and ongoing efforts to culture the BSS in captivity.


    Bio: Justin Crow was born and raised in Fort Worth, Texas. Following high school he relocated to Austin, Texas and entered the workforce. Eventually, his aspirations of working in conservation biology got the best of him and he completed his undergraduate degree earning a B.S. in Marine and Freshwater Biology from The University of Texas at Austin. He then pursued his life-long goal of becoming a Fish Biologist. Justin has had the opportunity to work as a Biological Sciences Technician at the SMARC since 2013. At the SMARC he served as a caretaker in the endangered and threatened salamander refugium. Following graduation Justin hopes to remain with the U.S. Fish and Wildlife Service and continue his career in conservation. Justin is married to his loving and supportive wife Ana, and they have two amazing daughters who share their love of nature.


    Thesis Defense


    Determining the Seasonal Diets of Sable Antelope (Hippotragus niger) at Mason Mountain Wildlife Management Area


    Amanda Hargrave


    Major Advisor: Dr. Thomas R. Simpson           

    Committee Members: Dr. Dittmar Hahn, Dr. Floyd Weckerly, Dr James Gallagher

    July 2, 2015 at 10:00 am in Supple 153-A


    Abstract: The seasonal diets of sable antelope at Mason Mountain Wildlife Management Area were investigated from June 2013 to April 2014 using microhistological technique and an emerging technique of DNA analysis of fecal material.  Forty samples were collected during summer 2013 with 20 samples collected in each of the remaining seasons. Vegetational analyses were conducted simultaneously with the fecal collection. Herbaceous plants were sampled using the Daubenmire method. Woody plants were sampled using the line-intercept method. Annually, the bulk of the diet was comprised of little bluestem (Schizachyrium scoparium) and Texas wintergrass (Stipa leucotricha). Plant use by sable antelope was compared with the availability of plants at Mason Mountain WMA to determine if sable antelope were selectively feeding. During spring, summer, and fall little bluestem (Schizachyrium scoparium) was selected. During the summer, switchgrass (Panicum virgatum) was also selected. Sable antelope selected Texas wintergrass (Stipa leucotricha) during the winter.  DNA analysis targeted a portion of the chloroplast trnL (UAA) intron and 13 samples were successfully amplified and sent to the University of Texas at Austin’s Genomic and Sequencing Analysis Facility for next-generation sequencing. The vast majority of plants consumed by sable antelope were grasses. While sable antelope may not compete for food resources with browsers such as white-tailed deer and greater kudu, careful consideration should be made when stocking with other grazers such as cattle, waterbuck, gemsbok, and scimitar-horned oryx.


    Bio: Amanda Hargrave was raised in a small town in East Texas called Mabank where she first developed an interest in the natural world. She began her undergraduate career at Trinity Valley Community College and obtained an associate’s degree in liberal arts. She received a Bachelor of Science in Wildlife Biology in 2012 from Texas State University in San Marcos, Texas. While completing her undergraduate requirements she served as both vice president and president of the student chapter of The Wildlife Society and obtained an internship with Texas Parks and Wildlife Department at Government Canyon State Natural Area. In 2013, she entered the graduate program in Wildlife Ecology at Texas State University. While enrolled in the program she completed a second internship with Texas Parks and Wildlife Department at Mason Mountain Wildlife Management Area. As a graduate student she completed the GIS certification requirements through the geography department and worked as an instructional assistant for Modern Biology II, Techniques in Wildlife Management, and Vertebrate Natural History. Amanda’s goal is to help manage and conserve the natural resources and wildlife in Texas, while also gaining experience in the field and becoming more knowledgeable on ecological relationships and resource management.


    Dissertation Defense


    FUNCTIONAL CHARACTERIZATION OF SAUR GENES IN PLANT GROWTH AND DEVELOPMENT


    Praveen Kumar Kathare

    Major Advisor: Dr. Nihal Dharmasiri


    Committee Members: Dr. Dana Garcia, Dr. Hong Gu Kang, Dr. Sunethra Dharmasiri,

                                     Dr. Rachell Booth, Dr. Enamul Huq       

    Wednesday, July 1, 2015, 02:00 PM Supple 257


    The plant hormone auxin regulates many key aspects of plant growth and development as well as plant response to both biotic and abiotic stresses. This is mainly achieved through controlled gene expression of group of three early auxin responsive gene families. SAUR (Small Auxin Up RNA) family of genes are one of three early auxin responsive genes, whose expression is induced within minutes of auxin application. In model plant Arabidopsis, SAUR family consists of more than 72 genes. However, except for few genes, functions of most of these SAUR genes are not known. With the aim of functional characterization of some of Arabidopsis SAURs, we selected four different SAUR genes belonging to clade III of the SAUR family. Results from this work indicate that all the four SAUR proteins physically interact and form complex with calmodulin proteins. These four genes are involved in the regulation of cell and organ elongation, and therefore, overexpression of any of these genes results in pleotropic growth related defects. SAUR overexpression transgenic seedlings are defective in polar auxin transport and are significantly insensitive to plant hormone ethylene. Moreover, SAUR overexpression and loss-of-function mutants show altered responses to salinity and drought stress responses. Taken together these data suggest that all four SAUR genes are important modulators of plant growth and development, and also regulate plant responses to environmental stresses.


    BIO: Praveen Kumar received his BS majoring in Biotechnology from Gulbarga University- Gulbarga, India and MS in Biotechnology from Bangalore University- Bangalore, India. He entered aquatic resources Ph.D. program in spring 2010. As an instructional assistant he has taught laboratory courses in plant physiology and developmental biology. He is also working as a research assistant in the Department of Biology.


    Thesis Defense


    Characterization of AFB5 in Arabidopsis Auxin Signaling


    Lauren Minter


    Major Advisor: Dr. Nihal Dharmasiri                      

    Committee Members: Dr. Sunethra Dharmasiri and Dr. Dhiraj Vattem (Department of Nutrition and Foods)

    Monday, June 29, 2:00 PM, Norris Room  


     Auxin regulates nearly every aspect of plant growth and development by controlling both genomic as well as non-genomic responses. Genomic responses are regulated through the degradation of a group of transcriptional repressors called Aux/IAA proteins. These repressors are degraded through the ubiquitin-proteasome pathway involving SCFTIR1/AFBs in which TIR1/AFBs function as auxin co-receptors. TIR1 gene family in Arabidopsis consists of 6 genes, of which AFB4 and AFB5 are distantly related to TIR1. We isolated two mutant alleles of Arabidopsis AFB5 (pic3 and pic59) through a genetic screen using picloram, a synthetic auxin commonly used as an herbicide.

                Both mutant alleles exhibit differential primary root growth resistance to different auxinic chemicals. AFB5 expresses highly in tissues with actively dividing cells, such as the primary and lateral root tip, lateral root primordia, and hypocotyl, suggesting that AFB5 may function in cell division and/or expansion. Altered lateral root densities have been observed in pic3 and pic59 and AFB5::AFB5-GUS expresses highly in lateral root primordia, indicating that AFB5 may regulate lateral root development. Results so far indicate that AFB5 may have a limited role in Aux/IAA degradation, suggesting that it functions partially or completely differently from TIR1. Additionally, recent published data suggests that ROP GTPases regulate both auxin and ABA signaling. Two members of this family, ROP2 and ROP6 express highly in actively dividing tissues and mutants show defects in lateral root development. We hypothesized that the functions of AFB5 may be regulated through ROP GTPases and found that AFB5 expression is significantly higher in the rop2 and rop6 background. Using phenotypic analysis of rop2 or rop6 and afb5 double mutants, we sought to identify the role of AFB5 in plant growth and development.


    Bio:  Bio:  Lauren was born and raised in Austin, Texas. In 2013, she earned a B.S. in Biology with a minor in Women's Studies from Texas State University-San Marcos, during which she conducted undergraduate research in the Dharmasiri lab. Upon completion of her bachelors, she join the lab as a full-time graduate student, where she continued research on auxin signaling, taught a variety of labs as an Instructional Assistant, and served in the Student Government as the Graduate Representative for the College of Science and Engineering.


    Thesis Defense

     

    The effects of net confinement and rapid salinity change on red drum (Sciaenops ocellatus) fed supplemented diets


     Shawntel M. Lopez


     Major Advisor: Dr. Joseph Tomasso              

    Committee Members:  Dr. Dittmar Hahn, Dr. Michael Forstner, and Dr. Hardin Rahe

     Friday June 26, 2015, 9:00 AM FAB 130


    Due to increasing temperatures and changing precipitation patterns, hatchery raised juvenile red drum are sometimes faced with abrupt environmental changes when stocked into coastal bays. For this study, red drum fingerlings were fed either a reference or supplemented diet (2% salt, 2% salt and a prebiotic, 3% salt, 5% salt, or 7% salt) to determine if diet supplementation fostered better tolerance to net confinement and rapid salinity changes. Fish were fed diets for four to five weeks and then confined in a net for one hour, during which salinity was increased to either 40‰ or 55‰. Seventy-two hours after confinement, 100% survival was seen in those placed in the 40‰ and 0-47% survival was seen in treatment groups raised to 55‰. Plasma osmolality levels, plasma glucose concentration, plasma lactate concentrations, liver glycogen levels and hematocrits showed no significant variation across diet treatments or when comparing pre- and post-confinement values. Results of this study suggest that red drum fed a salt supplemented diet may be able to better tolerate rapid salinity increase, but further research is needed. However, if we compare performance of fish fed the reference diets in both experiments, it is clear that transfer of red drum to 40‰ may be feasible, but transfer to 55‰ risks losses of some or all of the fish.


    Bio:  Shawntel M. Lopez was born and raised in Pasadena, Texas. She graduated from Texas State University in August of 2013 with her Bachelors degree in Biology, and immediately began work on her Masters degree in Biology at Texas State University. Upon graduation, she will return to her hometown of Pasadena, TX to mold the minds of future scientist as a high school Biology teacher.


    Thesis Defense


    A SPATIOTEMPORAL HABITAT FRAGMENTATAION ANALYSIS

    FOR THE HOUSTON TOAD (BUFO HOUSTONENSIS)

     


    Derek M. Wallace


    Major Advisor:  Dr. Michael R. J. Forstner           

    Committee Members: Dr. Jennifer Jensen, Dr. Joseph A. Veech

    Thursday, June 25, 2015, 1:00 pm Supple Science Building, Norris Room


    The loss of biodiversity worldwide is an issue of great concern and in the last quarter century amphibians have been at the forefront of this issue. Of particular note for South-Central Texans is the regional species Bufo houstonensis (Houston Toad). B. houstonensis is a Texas endemic amphibian first described as a species in 1953 and was the first amphibian listed on the U.S. Endangered Species Act in 1970. Historically the species has been found in the following counties: Austin, Bastrop, Burleson, Colorado, Fort Bend, Harris, Lavaca, Lee, Leon, Liberty, Milam, and Robertson, but is reported to be extirpated from Harris, Burleson, Fort Bend and Liberty counties. To date, Bastrop County has maintained the largest population since the 1970’s. The causes behind B. houstonensis’ decline across the range are largely attributed to habitat destruction and degradation. In addition to habitat destruction, two severe droughts have occurred across the range of B. houstonensis, the most recent resulted in a severe wildfire which drastically reduced critical habitat within Bastrop County. In 2001, the United States Fish and Wildlife Service established Focus Areas in order to direct conservation within smaller areas across the species range. Given the endangered status of B. houstonensis it is necessary to better understand these Focus Areas regarding the habitat of B. houstonensis on a temporal basis and use any information derived to assist in future conservation efforts.


    Bio: Derek Michael Wallace was born in Longview, Texas and relocated to Central Texas in 2001. He enrolled in Texas State University – San Marcos in 2004 and received a B.S. in Biology, with a minor in English, in 2008. After two years working for the Texas Department of State Health Services he enrolled in the Wildlife Ecology Masters program at Texas State University – San Marcos in 2011. Between 2011 and present he also worked as a biological consultant performing field work for the protection and conservation of the Houston Toad.


     

    Thesis Defense


    GOLDEN EAGLE NEST SITE SELECTION AND HABITAT SUITABILITY MODELING ACROSS TWO ECOREGIONS IN SOUTHERN NEVADA


    Sarah Weber


    Major Advisor: Dr. Randy Simpson and Dr. John Baccus


    Committee Members:  Dr. Michael Clay Green

    Thursday, June 25, 2015, 11:00 AM Room 153


    Because of perceived declines in golden eagle (Aquila chrysaetos) populations in the western United States, United States Fish and Wildlife Service (USFWS) are closely monitoring population trends throughout their range.  An inventory of golden eagles in 2 ecosystems in Nevada (northern Mojave Desert and southern Great Basin) was conducted from 2011-2014 with the objectives to: (1) locate nest sites and territories across several mountain ranges (Kawich Range, Belted Range, Stonewall Mountain, Cactus Range, Black Mountain, Quartz Mountain, Tolicha Peak, Sheep Mountain, Pintwater Range, Desert Range, Pahranagat Range, Spotted Range, Buried Hills, Half Pint Range),  (2) estimate breeding population, and (3) map suitable nesting habitat based on nest site parameters. Cliff and canyon habitats of the southern Great Basin and northern Mojave Desert were surveyed by helicopter from 2011-2014 for active and inactive nests and to measure nest site parameters. Nest site parameters used for analysis were: general location, mountain range, cliff height, viewshed, soils, geology, elevation, aspect, slope, habitat, use, productivity, distance to nearest road and distance to water. Using these parameters, a suitability index was created using the program MaxEnt to map potential nesting habitat throughout they study site boundaries. A total of 96 nest sites (old/abandoned and newly decorated) were analyzed. During the four years of inventory 27 active nests produced 36 fledglings. Two nests were occupied for three years and three nests had double year occupancy. Results of this project will aid in establishing a monitoring program to provide guidance for avoiding and minimizing disturbances and other kinds of future “take” for federal agencies in consultation with USFWS.


    Bio:  Sarah A. Weber was born in Indianapolis, IN and moved to San Antonio, Texas in 1998. She graduated from Texas A&M University in 2006 with a B.S. in Wildlife and Fisheries Science and a concentration in Conservation Biology and Biodiversity. Sarah has continual education in Geographic Information Systems (GIS) from Penn State University and has a current application pending for Certified Wildlife Biologist through The Wildlife Society. Sarah is president and co-owner of a biological and spatial surveying company called Bio-Spatial Services, Inc. Sarah has been in the consulting field for eight years and is looking forward to continuing to provide high quality expertise in the field of Natural Resources. Sarah is an avid field biologist and enjoys helping landowners (public and private) manage their wildlife and biological resources with sound science and wise use.

    Sarah has a 4 year old daughter, Olive and lives in the Texas Hill Country. 


    Thesis Defense


    The Physiological Effect of Hypersalinity and Temperature

    on Juvenile Red drum


    Erica M. Molina

    Major Advisor:  Dr. Joseph Tomasso       

    Committee Members:  Dr. Dittmar Hahn, Dr. Michael Forstner and Dr. Hardin Rahe

    Thursday June 25, 2015, 8:00 AM FAB 130


    Recreational and commercial fishing have decreased the population of many fish species. As a consequence, fish hatcheries in many costal states produce fingerlings, for stocking, in effort to increase overfished populations. The purpose of this study was to determine the physiological response of juvenile red drum to warm, hypersaline conditions in order to determine whether fish are able to acclimate to life in the wild during drought conditions (ie. very low instream flows to the bays). Red drum, Sciaenops ocellatus, fingerlings were cultured in recirculating systems for 4-5 weeks at different temperature/salinity regimen, i.e. at a temperature of 30°C and a salinity of 35 ‰ (reference conditions), and a temperature of 34°C and either 45 ‰, or 55 ‰ salinity (treatment conditions). Comparison of physiological stress indicators such as hematocrits, plasma osmolality concentrations, plasma lactate concentrations, plasma glucose concentrations and liver glycogen levels in fish held under reference conditions or increased temperature and salinity regimen did not result in statistically significant differences between treatments. Indicating, that as long as food is not limiting and water quality is acceptable, juvenile red drum can tolerate warm, hypersaline conditions with no apparent detrimental effects, if gradually acclimated to environmental conditions prior to exposure to these conditions.


    Bio:  Erica was born and raised in San Antonio, Texas. She received an Associates degree in Veterinary technology from Palo Alto College and has worked as an LVT at the Emergency Pet Center while in school. She also received her Bachelors in Animals Science with a minor in Biochemistry and then immediately went into her Maters program in Biology at Texas State University. After graduation she will be moving to Auburn, Alabama to pursue her PhD in Biology under the supervision of Dr. Mendonca. 


     

    Thesis Defense

    Effect of compost tea on plant growth performance and the fate of microbial communities in soil


    Name Elise Claire Valdes


    Major Advisor: Dr. Dittmar Hahn

    Committee Members: Dr. Michael Forstner, Dr. Robert McLean, and Dr. Hardin Rahe

    June 24, 2015, 10.00 AM, Supple 257


    Compost tea is a popular amendment used to improve soil quality and to control soil-borne diseases in plants. With proper brewing, compost tea contains many of the beneficial microbes and nutrients of compost, but is more easily applied to plants. The purpose of this study was to (i) analyze the fate of microbial communities in spent mushroom substrate compost tea applied to soil microcosms planted with corn, and (ii) determine if growth of corn is influenced by specific constituents from compost tea, including microbes only, nutrients only, or a combination of both (i.e. the complete compost tea). Two trials were performed, one with anaerobic soil conditions and a second with aerobic soil conditions. Bacteria and Eukarya were quantified over the 30 days with sampling events on days 0, 1, 2, 5, 10, 20, and 30, as were plant growth performance characteristics like root and sprout length or their biomass. Results demonstrated a significant drop (70-90%) in abundance of microbes after application of compost tea, without recovery during the 30-day incubation period. Plant growth performance characteristics were not statistically significantly different for corn on soil receiving compost tea or separated components (i.e. microbes or nutrients) only, or a water control. While these results cannot support assumptions on beneficial effects of compost tea on plant growth performance and microbial communities in soil after application, further scientific research should consider long-term studies with different plant species and soils to further investigate potential beneficial effects of compost tea.


    Bio:  Elise Claire Valdes is originally from Sugar Land, Texas. She received her B.A. in Agriculture- Animal Science from Texas State University. She initially became interested in sustainable agriculture after a trip to the Galapagos Islands. Soon after, she received the opportunity to get her Master’s degree in Biology at Texas State University under a USDA grant and with a sponsorship from the Kitchen Pride Mushroom Farm, Inc. The grant allowed her and five other students to go on a study abroad to Costa Rica last May, where she gained further insight into the dynamics of sustainable living.


    Thesis Defense

    Population Genetics of the Big Bend Slider (Trachemys gaigeae gaigeae) and the Red Eared Slider (Trachemys scripta elegans) in the Contact zone in the Lower Rio Grande drainage of Texas


    Name: Lauren Schumacher

    Major Advisor:  Dr. Michael R.J. Forstner (Chair)   

    Committee Members: Dr. M. Clay Green, Dr. Thomas R. Simpson

    Monday, June 22, 2:30 PM, Supple Science Building, Norris Room


    The red-eared slider (Trachemys scripta elegans) is well-known for its popularity in the pet trade. It is also known for its near cosmopolitan distribution, which is partly due to the release of these pet turtles. When introduced to a new area, non-native T. s. elegans can hybridize with other native Trachemys species. An example of this occurs between T. s. elegans and the Big Bend slider (T. gaigeae gaigeae) in western Texas. Recent research and trapping efforts have primarily focused on Big Bend National Park. Mitochondrial haplotypes unique to T. g. gaigeae have been observed in T. s. elegans inhabiting Rio Grande tributaries downstream of the park, which could indicate historical hybridization. This study sought to address these concerns by utilizing specifically targeted additional sampling within these areas. I used twenty polymorphic microsatellite loci and model-based clustering methods to detect hybrids. Out of the 120 turtles sampled, 7.5% were identified as hybrids using the program Structure v2.3.4, and 23.3% were identified as hybrids using NewHybrids v1.1. My results supported the findings of past research as hybridization was found between T. g. gaigeae and T. s. elegans. They also supported the idea that morphology cannot identify hybrids. Some of the backcrossed individuals were located in areas outside of the range of T. g. gaigeae. This may represent an ancestral polymorphism caused by previous gene flow between individuals in the Rio Grande, Pecos River, and Devils River.


    Bio: Lauren grew up in a small town in southern Illinois where she was constantly bombarding her classmates with fun facts about one animal or another. She eventually moved to Florida to earn her B.S. in Marine Biology from Florida Institute of Technology. After graduation, she started working at the Dauphin Island Sea Lab where she assisted with a number of projects that involved the restoration and subsequent monitoring of coastal marine habitats. This was followed by three months of fieldwork in the Mojave Desert assisting with a desert tortoise disease ecology project out of the University of Nevada, Reno. She joined the Population and Conservation Biology Masters Program at Texas State in the fall of 2012. While at Texas State, Lauren has taught Genetics labs and worked as a Houston toad monitor.


    Thesis Defense


    Landscape scale habitat associations of Sprague’s Pipit (Anthus spragueii)

    overwintering in the southern United States


    John A. Muller

    Major Advisor:  Dr. Joe Veech           

    Committee Members:  Dr. Clay Green, Dr. Rich Kostecke (Nature Conservancy)

    Monday, June 22, 10:00 AM in Norris Conference Room


    Sprague's Pipit is a North American endemic migratory grassland songbird that has experienced a substantial population decline over the last half-century. There has been very limited research done on Sprague’s Pipit especially on their wintering grounds. There is no complete account of their historic wintering range and there is also limited knowledge about the status of their current wintering range in the United States and Mexico. On the breeding range, Sprague’s Pipits seem very selective in their habitat use, although there are reports that there may be a broader use of habitats on the wintering grounds. My objective was to determine the habitat types that Sprague’s Pipit associates with at the landscape scale. I used land cover data from the National Land Cover Database GIS layers, CropScape GIS layer, and pipit point locations retrieved from eBird. I examined landscape-scale (1, 2 and 5 km) habitat associations of Sprague’s Pipits over wintering in areas of Arizona, New Mexico, Texas, and Louisiana. I then compared these habitat associations to those of random locations and to locations of the closely related American Pipit. I found that Sprague’s Pipit locations had minimal canopy cover, lower percent cover of woody vegetation and certain agriculture land cover types in comparison to random locations. I also found that although Sprague’s Pipit is known to be negatively affected by non-native and anthropogenic grasslands at fine spatial scales, these grassland types may be suitable for the species at the landscape scale. Sprague’s Pipit also appeared to be much less of a habitat generalist than the more common American Pipit.  The results of my study could potentially be used in landscape-level planning for the conservation of the species on its wintering grounds.


    Bio:  John was born and raised in Austin, TX. He received a B.S. in Wildlife Biology from Texas State University in 2012. After receiving his bachelor’s degree he worked as a biotech and wildlife monitoring intern for the USFWS for 18 months at both Tishomingo NWR, Oklahoma and Buenos Aires NWR along the Arizona/Mexico border. He started the M.S. program in Wildlife Ecology in January of 2014, and has been working as a graduate research assistant.


    Dissertation Defense


    Efficacy and Efficiency of Head-starting and Captive Propagation of an Endangered Amphibian: Implications for Continued Population and Habitat Management Following Catastrophic Wildfire


    Melissa Jones


    Major Advisor: Dr. Michael Forstner
    Committee Members:  Dr. Dittmar Hahn, Dr. Floyd Weckerly, Dr. Audrey McKinney and Dr. Todd Swannack

    Friday, June 19, 2015, 11:00 AM Norris Room


    The Lost Pines ecoregion of Texas is a loblolly pine (Pinus taeda) and oak (Quercus stellata) dominated woodland forest with remaining fragments in Austin, Bastrop, Colorado and Fayette Counties. Bastrop County Texas continues to support the largest known and best studied population of Houston toads (Bufo [Anaxyrus] houstonensis). The Houston toad was first described in Houston, Texas in 1953, and was the first animal from Texas and first amphibian federally listed as an endangered species.  To date, nearly all recovery efforts have centered on the “robust” population remnant in Bastrop County. Houston toad populations have remained in a continual decline consequent of multiple stressors, including habitat fragmentation, urban growth of the city of Bastrop, red imported fire ants, fertilizers and chemical run off, agricultural practices, drought, and most recently, catastrophic wildfire. The aftermath of the Bastrop County Complex fire of 2011 has left the county with the need for immediate, active and continual restoration of plant communities on public and private land. This recent fire event now presents us with the rare opportunity to explicitly test habitat suitability and species survivorship pre and post catastrophic wildfire on native amphibian populations. I seek to provide data that are relevant to continued population conservation programs and the ongoing habitat remediation and restoration efforts in Bastrop County. I have investigated 1) the efficacy and effectiveness of head-starting and captive propagated releases of Houston toads; 2) assessed habitat suitability and the effects of catastrophic wildfire on Houston toad populations, and 3) assessed familiarity and community support of recovery efforts for the Houston toad among Bastrop residents. My results will guide future management strategies and contribute to conservation recovery efforts for the remaining Houston toads in this altered landscape.


    Bio:  Melissa Jones was born in San Antonio, TX on March 29th 1980 to Curtis and Carolyn Jones.  In 2002, she received her Bachelors of Science degree in Zoology from Southwest Texas State University. In 2004, she returned to Texas State University and received her Masters of Science degree in Wildlife Ecology in 2006. In 2010, she entered the Aquatic Resources doctoral program at Texas State University to focus on habitat and population management of the endangered Houston toad.


     

    Thesis Defense


    AUTOMATED DETECTION OF RARE AND ENDANGERED ANURANS USING ROBUST AND RELIABLE DETECTION SOFTWARE


    Andrew R. MacLaren


    Major Advisor:  Dr. Michael R. J. Forstner           

    Committee Members: Dr. Shawn F. McCracken, Dr. Floyd W. Weckerly

    Friday. June 19, 2015, 8:00 AM Supple Science Building, Norris Room


     Abstract:  Amphibian populations are experiencing rapid rates of decline, the causes of which are sometimes controversial. The vocalization of the male anuran is used as an indication of a potential breeding event. Researchers have been relying on these vocalizations to monitor the health, reproductive status, and diversity of anuran populations for centuries. As technology advances so does our ability to innovate and improve the way anuran populations are monitored. One such innovation comes in the form of portable commercially available audio recording devices (ARD). These tools enable researchers to capture the sounds produced by populations of any vocalizing animal species and analyze them using machine-learning techniques of pattern recognition. The application of these techniques is understudied and not well documented for anurans. I conducted rigorous testing of these techniques to improve methods of monitoring populations of the endangered Houston Toad (Bufo houstonensis). The desired result of these tests would be a reliable and robust tool for recognizing the call of the Houston Toad. This would allow researchers to search vast quantities of digital audio files for the unique sound of this animal. I also compared the efficacy of this machine-learning technique to a highly trained professional listening for the call. Researchers often doubt the reliability of automated techniques, thus my recognition tool must be able to perform capably. Additionally, I employed these automated machine-learning techniques to document the presence or absence of the Houston Toad in two counties of Texas, and then coupled those data with highly resolute details of the environmental conditions to examine call phenology of the Houston Toad and graphically visualize this behavior across a complete chorusing season.


    Bio: Andrew MacLaren relocated to Houston, Texas from Bay City, Michigan in 2000. Received a B.S. Biology, minor in Philosophy, in December of 2013 from Texas State University - San Marcos. He joined the Master of Biology program here at Texas State beginning June 2014. He also worked as a biological consultant monitoring populations of Houston Toads in the interim of his enrollment as a student.


    Thesis Defense


    Using a Habitat Suitability Model and Molecular Analyses to Aid in the Conservation Management of the Texas Tortoise, Gopherus berlandieri


    Anjana Parandhaman


    Major Advisor:  Dr. Michael R. J. Forstner           

    Committee Members: Dr. Shawn F. McCracken, Dr. Thomas R. Simpson, Dr. M. Clay Green

    Thursday, June 18, 2015, 2:00 PM Supple 257-A


    The Texas tortoise, Gopherus berlandieri, is a threatened species in the state of Texas and strict conservation action is required to ensure that continuing population decline does not occur. The historical range of the Texas tortoise includes a much larger area than recent observations support, especially in the eastern range. Assessing the habitat suitability of the eastern historical range of the species and determining whether this region still supports the species will aid in its conservation. For the first chapter of my thesis, I conducted road surveys, from March to October of 2014, in these understudied regions. GPS coordinates of tortoises from these surveys, along with coordinates obtained from online databases were used with environmental predictors to model habitat suitability for the species using ArcGIS and Maxent. I found that there are some patches of habitat in the eastern range that could potentially support the species. In addition, some areas of suitability exist outside the species range. For the second chapter of my thesis, a population genetics study was carried out using tortoise samples, found outside its current and historic range, to determine genetic diversity and population structure using microsatellite loci. I found that selected tortoises likely belong to the same population, although some loci have a relatively high amount of genetic diversity. Both of my chapters attempt to explain the poorly understood factors of habitat suitability and aid in genetic diversity research for the Texas tortoise. This in turn will allow for better management and conservation of the species throughout its range.


    Bio: Anjana was born in a land far, far away (also known as Chennai, India) and obtained her Bachelor’s degree in Zoology from Stella Maris College, Chennai, in 2011. She spent a year working on coastal issues, crocodiles and Olive Ridley Sea turtles, and volunteered for various other organizations. Anjana then moved to Texas, joined the Masters program in Wildlife Ecology at Texas State University in January of 2013, and has been trying to do awesome science ever since. 


     

  • Thesis Defense


    THE EFFECTS OF WATER VELOCITY AND SEDIMENT COMPOSITION ON COMPETITIVE INTERACTIONS BETWEEN NATIVE AND INVASIVE MACROPHYTE SPECIES IN A SPRING FED RIVER


    Jacob N. Bilbo


    Major Advisor: Dr. Thomas B. Hardy             

    Committee Members: Dr. Paula S. Williamson & Dr. Weston H. Nowlin  

    Friday, April 24, 2015, 1:30 PM FAB 130


    Abstract:  Hydrilla (Hydrilla verticillata) is an invasive species that is problematic globally and also in the San Marcos River where it competes with native species. Hydrilla has been described as the “perfect aquatic weed” because it is able to propagate under a wide range of environmental conditions including low nutrient and variable light conditions (Langeland 1996). Treatment methods for control of non-native aquatic plants can be restricted due to the co-occurrence of native endangered species, requiring an integrated approach of several methods for restoration, including removal by hand, and manipulating environmental factors to encourage growth of native species. I conducted a competition study to determine if native species can out-compete non-native species under a set of environmental conditions. The experiment was conducted within Spring Lake at the headwaters of the San Marcos River, Hays Co. Texas between 03/28/2014 and 05/21/2014. I used a three-factor replacement design: (water velocity, substrate type, and competitive pressure) to assess competitive interaction between a native and non-native aquatic macrophyte. Illinois pondweed (Potamogeton illinoensis) and hydrilla were potted in monoculture (intraspecific competition) and mixtures (interspecific competition) using sand or silt sediment, and high or low velocity for a period of seven weeks. Above- and belowground dry biomass, total stem length, and number of stems were measured. Across all treatments, pondweed demonstrated significantly (P<0.05) higher growth rates than hydrilla. Substrate type and monocultures were not statistically significant factors in plant growth, however growth indices indicated that total dry biomass of both plants was slightly higher in sand substrate and high velocity. I also found intraspecific competition was greater than interspecific competition for both species, and that both species produced more biomass when in monoculture and at lower ratios in mixtures. Therefore, data from this study suggests optimal growing conditions for Illinois pondweed to out-compete hydrilla are in sand substrate and high velocity conditions. Continued research is required to further understand the competitive interactions of native and non-native macrophyte species in the San Marcos River.


    Bio:  Jacob Bilbo is originally from El Paso, TX where he earned his B.A in Interdisciplinary Studies at the University of Texas at El Paso. He became interested in aquatic biology after researching arctic zooplankton community dynamics for his senior thesis. While pursuing his M.S. in Aquatic Resources at Texas State University, he has worked as a consultant for the Southeastern Aquatic Resources Partnership. He then worked as a graduate research assistant at the Meadows Center for Water and the Environment conducting habitat restoration in the San Marcos River.


    Thesis Defense


    Small mammal communities and urban land cover associations in

    San Marcos, Hays County, TX


    Lauren Cody


    Major Advisor: Dr. Thomas R. Simpson            

    Committee Members: Dr. M. Clay Green and Dr. Ivan Castro-Arellano

    April 17, 2015 1:00 PM SUPP 153-A


    The importance of understanding small mammal diversity in urban areas is multifaceted. Small mammals affect predator population dynamics, habitat structure, and the spread of zoonotic diseases. Small mammal populations can help evaluate habitat fragmentation and quality and can potentially delineate habitat management strategies. My objectives were to determine the composition and diversity of small mammal communities within the city of San Marcos, and to evaluate relationships between composition and diversity by meteorological seasons and land cover type. I surveyed 20 sites within urban San Marcos between August 2013 and May 2014 for a total of 11,590 trap nights over 4 seasons. A total of 280 small mammals among 12 species were captured; the hispid cotton rat (Sigmodon hispidus) had the highest relative abundance overall (46.1%), in all seasons, and in all land cover types except urban developed, where the house mouse (Mus musculus) was most abundant. The northern pygmy mouse (Baiomys taylori) was also significantly more abundant than other captured species. Grassland sites showed the highest trap success (7.7%). The highest diversity index (1.39) and species richness (n = 5) were found in Speck Parking Lot, an urban developed site. Bicentennial Park, classified as forest/woodland, yielded no captures over the entire survey period. The Lower Purgatory Greenspace area, a grassland site, had the highest relative abundance (n = 87) and trap success (15.9%). While I did not find a significant difference in species diversity based on land cover type or season, more surveys should be conducted to gain a clearer picture of the small mammal communities of this area. Many sites did not yield any captures during some or all seasons, potentially deflating species diversity indices. I also saw fewer captures in the spring season, most likely due to the extreme cold winter season experienced by the San Marcos area. Two of the forest/woodland sites had large stands of privet trees (Ligustrum spp.), which likely account for lower relative abundance in those areas. Now that areas with high abundance and diversity of small mammals have been identified in San Marcos, these sites can provide opportunities for future surveys and projects, and can be used to assess and monitor the habitat quality of this urban area.


    Bio:  Lauren Cody was born in Fort Sill, OK, but quickly moved to Texas. She grew up in San Antonio and received her B.A. in Biology from the University of Texas at Austin in 2007. After working in environmental testing for a pharmaceutical company in North Austin, she decided to pursue higher education. While working towards her M.S. in Wildlife Ecology here at Texas State University, she has volunteered with Austin Water Quality and Plateau Land and Wildlife Management, and has been an IA for Functional Biology labs.


    Thesis Defense


    INFLUENCE OF LIGHT AND TEMPERATURE ON DENSITY OF SWALLOW NESTS


    Lorissa Di Giacomo


    Major Advisor: Dr. M. Clay Green          

    Committee Members: Dr. Ivan Castro-Arellano & Dr. Thomas R. Simpson  

    Monday, April 13, 2015, 12:00 PM Supple 153-A


    Habitat parameters that affect survival and reproduction can be enhanced or degraded from human activities including disturbance and development. While the development of human-made structures can obviously degrade (e.g. loss of habitat) a species’ ability to survive and reproduce, human structures can also promote population growth through a species use of these structures for basic life history requirements, such as nesting and roosting. My study examined the overlap (spatially and temporally) of Cliff Swallows and Cave Swallows during the nesting season as well as the seasonal use of 5 bridges in Central Texas by both species. Specifically, I examined spatial isolation between swallow species and investigated the influence of temperature and ambient light properties on nest site selection. For both years of this study, Cliff and Cave Swallows were present during our surveys; while the numbers were variable between years and among bridges, in general Cliff Swallows were the dominant species present. In contrast, Cave Swallows were only recorded at two of the five sites: B2-Plum Creek, and B5- Blanco State Park during both years. I found no significant interaction between bridges and probe (F = 0.901, P = 0.493) for mean temperature (°C) but the three bridges (B2, B3, B5) did significantly differed in mean temperature with B2 significantly warmer than B3 and B5 (F = 15.104, P <0.001). For mean light (Lux), I found a significant interaction between bridge and probe (F = 63.75, P <0.001) with all bridges receiving less light within the interior spans then the outer spans and the bridges differing significantly in overall ambient light; in order of decreasing light: B2, B3 and B5. Cave Swallows were found only within the interior spans of bridges (i.e. darker areas) and at the two bridges that received the less light. However, Cave Swallows did not appear to be influenced by temperature as Cave Swallows occupied the hottest (B2) and coolest (B5) bridges. Based on my results, it appears Cave Swallows are selecting bridge site that are relatively dark but not influenced as much by temperature at the nest site. Future studies are warranted to continue investigating the nest site selection of Cave Swallows as they continue to expand their range into the south western United States.  


    Bio:  Lorissa Di Giacomo earned a B.A. in Biology from Texas Lutheran University in 2012. While in college, she worked at the San Antonio Zoo as a Playleader. As a Population and Conservation Biology Master’s student at Texas State University, she was funded to do her research from Texas Department of Transportation. Upon graduation, Lorissa hopes to work for TPWD but until that time she will remain at the San Antonio Zoo, where she has been a part of for the past 11 years.


    Dissertation Proposal Defense

     

    Investigating Population Structure and Evolutionary History of Three Focal Taxa

    in the Edwards – Trinity Aquifer System Using Integrative Systematic Methods


    Emrah Ozel


    Major Advisor: Dr. Michael R. J. Forstner             

    Committee Members: Dr. David R. Butler, Dr. Benjamin F. Schwartz, Dr. Chris Nice, Dr. Marshal Hedin

    Monday, April 13, 2015, 9:00 AM, Supple 257A


    Caves are fascinating environments that harbor many obligate and facultative organisms. In general, these species share a set of troglomorphic characters at various degrees depending on their life cycles. Darkness, relative climatic stability and significant humidity lead the convergent evolution of subterranean lineages. Three focal taxa (Asellidae, Stenasellidae, Cirolanidae; Order: Isopoda / Ceuthophilus; Order: Orthoptera / Cambala, Speodesmus; Class: Diplopoda) in the Edwards – Trinity Aquifer system are selected to investigate the influence of these physical and climatic habitat features on subterranean evolution and population structure. Studies showed that morphological analysis can easily be deceived by the convergent nature of subterranean evolution. On the other hand, molecular techniques provide deeper insights on phylogeny and population structure; however, it is still a controversial idea to use molecular methods solely for defining species boundaries. Integrative systematics is a recent trend in biology aims to utilize various data sources for species delimitation process. In this study, I will seek to use high resolution three-dimensional morphological data, molecular genetic data including nuclear, mitochondrial and anonymous DNA markers and basic climatic data to infer species boundaries. In addition to this, taxon sampling will allow assessing colonization histories, habitat connectivity and inter/intra-cave variations. Also, using these analytical methods, some other parameters such as strength of convergent evolution and the effect of UV radiation can be estimated. Lastly, my research will be one of the few studies that follows an integrative approach to evaluate subterranean evolution in the Edwards – Trinity aquifer system of Central Texas.


    Bio: Emrah Ozel earned a BSc. degree in Biology from Hacettepe University, Ankara, Turkey. In 2010, he received a MSc. in Zoology from Hacettepe University, Turkey. He entered the Ph.D. program in the Department of Biology at Texas State University in Fall 2011. As a Ph.D. student, he has been employed as an instructional assistant for Genetics lab.


    Thesis Defense


    RIO GRANDE BEAVER (Castor canadensis mexicanus)  SURVEY IN

    BIG BEND NATIONAL PARK


    Howland J. Reich IV


    Major Advisor: Dr. Thomas R. Simpson

    Committee Members: Dr. Floyd W. Weckerly, Texas State University & Dr. M. Clay Green, Texas State University

    Thursday, April 9, 2105, 2:00 PM, LBJ 3-3.1


     The Rio Grande River and its tributaries are home to the southwestern subspecies of North American beaver, Castor canadensis mexicanus. National Park Service biologists and biologists of protected areas in Mexico are concerned with the status of beaver populatons in this area. The last survey for the Rio Grande beaver, sometimes known as the Mexican beaver, in Big Bend National Park was conducted in 1981 by P. Strong and J. Bissonette. My objectives were to document centers of beaver activity and estimate the beaver population in Big Bend National Park. I surveyed 130 km of Rio Grande River with kayaks and canoes from the mouth of Terlingua Creek to the mouth of Boquillas Canyon during several trips from February 2013 to May 2014. I recorded water depth, type of vegetation, sign of active beaver colonies (dens, beaver tracks, scat, and cuttings), and ranked the amount of beaver activity within each colony as high, medium or low.  From these data, I created a map in ArcGIS showing bathymetry of the river, vegetation profiles, and sites of active beaver sign. I delineated a total of 98 active beaver colonies in the study area. Analysis of water depth with respect to den locations indicated that colonies were located in the deeper pools along the Rio Grande.  I conducted camera surveys on 11 colonies to estimate the number of beaver in each colony.  With camera survey data and activity ranking of each colony, I estimated a population of 185 beaver occupying the 98 colonies. This represents a 38% increase in the beaver population along the Rio Grande since the 1981 survey.


    Bio:  Howland J. Reich IV (Joey) earned a B.S. in Wildlife Biology from Texas State University- San Marcos in 2013.  While in college, he worked as a wildlife biologist for a private landowner in the Texas hillcountry.  As a Wildlife Ecology Master’s student at Texas State University, he taught functional biology labs, worked as a wildlife biologist for All Out Ranch Improvements, and held an RA position conducting surveys of the Rio Grande beaver in Big Bend National Park.  Upon graduation, Joey will continue to work as a wildlife biologist for All Out Ranch Improvements.


    Thesis Defense


    Nutrient Limitation of Algae and Heterotrophic Bacteria in Reservoir Ecosystems:
    Implications for Pelagic Competition along a Trophic Gradient


    Amelia Everett


    Major Advisor: Dr. Weston Nowlin       

    Committee Members: Dr. Alan Groeger, Texas State University & Dr. Dittmar Hahn, Texas State University

    Wednesday, April 8, 2015, 1:00 PM, FAB 130


    In low productivity pelagic ecosystems with low concentrations of inorganic nutrients, bacteria have been shown to play a relatively greater role in C and nutrient cycling and the importance of bacteria is thought to decline as productivity and dissolved inorganic nutrients increases.  Plankton ecologists have proposed several mechanisms which lead to this pattern, but it is generally thought that bacteria should exhibit a competitive advantage over algae in unproductive systems with relatively high concentrations of dissolved inorganic C (DOC) and low concentrations of dissolved inorganic nutrients. However, there is a limited amount of data examining if the intensity of competition between algae and bacteria for inorganic nutrients varies with ecosystem productivity.  My thesis focused on examining the potential for competition between heterotrophic bacteria and algae across a productivity gradient in a group of 19 Texas and Ohio reservoirs. Across reservoirs, DOC:dissolved inorganic nutrient ratios decreased with increasing productivity, signifying a shift in the dominant forms of available nutrients for algae and bacteria along a trophic gradient. The N and P content of algal and bacterial cells (i.e., C:N and C:P) follow a similar pattern of increasing cellular nutrient content with increasing productivity. Concurrent nutrient limitation assays indicated that algae across reservoirs were equally likely to be primarily limited by N or P, whereas bacteria were most frequently primarily limited by P and rarely limited by C. The magnitude of nutrient limitation responses (i.e., a response ratios) were greater overall with P addition over N or C, likely due to competition for inorganic nutrients. Both algae and bacteria exhibited heightened response ratios to P than with N or C comparatively due to low concentrations of P found within unproductive systems, thus an important limiting nutrient in these reservoirs studied.


    Bio:  Amelia Everett earned a B.S. in Environmental Science- Marine and Coastal Resources from Texas A&M University- Corpus Christi in 2012. While in college, she worked as a research field technician for the Conrad Blucher Institute for Surveying and Science. As an Aquatic Resources Master’s student at Texas State University, she taught general ecology labs and held an RA position conducing water quality analyses for the San Marcos River in 2014. Upon graduation, Amelia will work as a GLOBE intern for the Nature Conservancy assisting in stewardship of private lands surrounding the Pedernales and Blanco River watersheds.


    Dissertation Defense


    Biological and Environmental Influences on Developmental

    Variation of Ungulates in Variable Environments


    Daniel M. Wolcott


    Major Advisor: Dr. Floyd W. Weckerly             

    Committee Members: Dr. R. Terry Bowyer, Dr. Paul L. Leberg, Dr. Thomas R. Simpson, and Dr. M. Clay Green

    Friday, April 3, 2015, 12:00 PM, Supple 116


     Fundamental to lifetime fitness is the amount of body development that occurs during the life of an individual. This is especially apparent in long-lived species in which age-structured populations and sexual dimorphism affect breeding success among individuals. A considerable amount of research has been conducted on ungulates in order to understand factors that affect developmental variation within populations. However, much of this work has been conducted in regions in which metabolism - and subsequently body development - is influenced by photoperiod and environmental seasonality. Recently, several studies have demonstrated that increasing environmental heterogeneity at high latitudes has negatively affected ungulate population dynamics. My dissertation focused on understanding factors that influence skeletal and somatic development of ungulates across variable environments. Specifically, I addressed developmental variation at critical life stages (natal to adulthood) and highlight new findings on body development in two species of new world cervids (Capreolinae). My dissertation demonstrated that seasonal limitations to body development, considered pervasive in ungulate populations, are less present in populations that experience benign winter conditions and higher degrees of environmental stochasticity. The new insights gleaned from this dissertation are beneficial in understanding how populations of these biologically and economically important species may adapt to changes in local climate.


    Bio: Daniel M. Wolcott was born in Daytona Beach, Florida, and raised in Memphis, Tennessee. He earned a B.S. in Biology with a pre-med emphasis from The University of Memphis in 2007. He continued his education by enrolling in the M.S. program at The University of Memphis with an emphasis in ecology under the advisement of Dr. Michael L. Kennedy. Upon receiving his M.S. in 2011, he began his Ph.D. in the Aquatic Resources program at Texas State University under the advisement of Dr. Floyd W. Weckerly. His research interests are largely focused around understanding factors that affect the diversity and distribution of species. He enjoys teaching and anything related to the outdoors and family. He is thankful to his wife of 8 years, Amy, and their two children Emma (7) and Millie (2) who have been supportive throughout his education. 


    Dissertation Defense


    Quantification of frankiae in soil


    Suvidha S. Samant

    Major Advisors: Dr. Dittmar Hahn, Department of Biology, Texas State University


    Committee Members: Dr. Jeffrey O. Dawson, University of Illinois at Urbana-Champaign, Dr. Mark Paschke, Colorado State University, Fort Collins, Dr. Michael Forstner, Department of Biology, Texas State University,  Dr. Bob McLean, Department of Biology, Texas State University

     

    Friday, April 3, 2015, 8:00 AM, Supple 257


    The genus Frankia represents nitrogen fixing bacteria that form root nodules with more than 200 actinorhizal plant species. In nature, Frankia is found in soil and in root nodules of specific host plants. Due to their low abundance in soil and difficulties to isolate them, most studies on Frankia focus on populations in root nodules, which are a natural locale of enrichment for Frankia. As a consequence, little is known about the ecology of Frankia in soil. This PhD. dissertation work therefore focuses on two basic objectives: (1) to develop molecular detection and quantification methods for the analyses of Frankia populations in soils, and (2) to elucidate the effects of environmental conditions on the fate of frankiae in soils. Initial work on the first objective resulted in the development of two SYBR Green based qPCR methods, using either rRNA gene sequences or nifH gene sequences as targets for the detection of all frankiae or specific subgroups in soils. Both qPCR methods are currently refined, and will finally be used to analyze Frankia populations in two studies: (1) to compare the abundance of indigenous Frankia populations in soils beneath alder and birch from 4 sites in Illinois to assess the effects of plant species and sampling location (rhizosphere, crown cover, no plant impact) on the abundance and diversity of indigenous Frankia strains, and (2) to determine variables that affect growth and abundance of specific indigenous Frankia populations in soil microcosms over time as a function of plant species and carbon resource supply. Overall, this dissertation will result in the development and application of molecular tools that will be used to increase our understanding of the fate of specific Frankia populations in soils.


    Suvidha (Suvi) Samant earned a BSc. in Zoology from Carmel College, Goa, India. In 2005, she received a MSc. in Marine Biotechnology from Goa University, India, and later earned an M.S. in Biological Sciences from Wichita State University, Kansas. She entered the Ph.D. program in the Department of Biology at Texas State University in Fall 2011. As a Ph.D. student, she has been employed as an instructional assistant for Microbiology and Microbial Ecology labs.



    Dissertation Proposal Defense


    Population Dynamics and Habitat Conservation for the Golden-cheeked Warbler (Setophaga chrysoparia)


    Adam Duarte

    Major Advisor: Dr. Floyd W. Weckerly and Dr. Jeff S. Hatfield                 

    Committee Members: Dr. James D. Nichols, Dr. Michael R. J. Forstner, and Dr. M. Clay Green

    Friday, March 13, 2015, 2:00 PM, Supple 116


     Central to wildlife conservation and management is the ability to forecast how species will behave and persist under future environmental conditions. To accomplish this, biologists must have a deep understanding of factors that impact population dynamics for a species of interest at a variety of spatial and temporal scales. During this seminar, I will discuss my dissertation research, which is centered on updating and extending our knowledge on golden-cheeked warbler (Setophaga chrysoparia) population dynamics and habitat conservation at multiple spatial scales. Specifically, I will present papers that examine warbler habitat change, survival, immigration, productivity, and population dynamics using a variety of contemporary statistical and geospatial analyses. Using Landsat imagery, I provided quantitative evidence for a large-scale reduction in total warbler breeding habitat, which became more fragmented across the warbler’s breeding range. I estimated survival probabilities using 20 years of capture-resight data that suggest previous warbler population models were overly optimistic with respect to adult survival. Further, I found no strong evidence for spatial variation in survival or temporal patterns in survival that relate to observed warbler population dynamics. Using long-term monitoring data, I found immigration was important to stabilize local warbler populations, indicating conservation and management plans need to be implemented at a larger spatial scale. Lastly, I used these estimates to program a range-wide, spatially explicit population model to project warbler population and habitat dynamics into the foreseeable future. The model results indicated population viability could be achieved under current conditions, and that increasing the amount of protected lands would have a substantial impact on warbler carrying capacities at the end of a 50-year simulation. Overall, this research will help guide conservation decision making for the golden-cheeked warbler, at the local and range-wide scale.


    Adam Duarte was raised in Wichita Falls, Texas. He earned a BS in Wildlife and Fisheries Sciences from Texas A&M University in May 2009, while simultaneously serving in the U.S. Marine Corps Reserve. In Fall 2009 he enrolled in the Wildlife Ecology MS program at Texas State University and joined Butch Weckerly’s lab. Upon completion of his Masters in May 2011 he joined the PhD program in Aquatic Resources at Texas State University, working with Butch Weckerly (Texas State University) and Jeff Hatfield (USGS Patuxent Wildlife Research Center). His research interests are focused on contributing to the effective conservation and management of natural resources through the application of modern statistical methods and geospatial analyses.



    Dissertation Proposal Defense


    RODENT ASSEMBLAGE STRUCTURE AND ECOLOGICAL FACTORS AFFECTING HANTAVIRUS PREVALENCE AT VARYING SPATIAL SCALES


    Matthew T. Milholland

    Major Advisor: Dr. Iván Castro-Arellano           

    Committee Members: Dr. Joe Veech,Texas State University, Dr. Rodney Rohde, Texas State University, Dr. Tom Lee, Abilene Christian University, Dr. Gerardo Suzán Azpiri, Universidad Nacional Autónoma de México

    Friday, February 27, 2015,11:00 AM, Supple 257


     Zoonotic pathogens are the dominant cause of novel and reemerging infectious diseases.  Hantaviruses (family Bunyaviridae) and their associated human diseases occur globally and differ according to their geographic distribution and type of illness exhibited in humans.  Prevention of these diseases requires surveillance of seroprevalence in animal populations.  Hantaviruses occur in close association with particular rodent, bat, and shrew reservoir hosts.  Small mammal assemblage structure and species richness are suggested as strong drivers for the maintenance and spread of hantavirus infections.  Climatic factors, such as precipitation, can influence reservoir density and abundance by increasing available food resources.  These fluctuations in rodent assemblage structure can contribute to the maintenance or reduction of hantavirus seroprevalence.  Dominance indices of competent hosts and assemblage characteristics may predict disease risk.  The research objectives of the dissertation are to:  1) to determine the ecological correlates of hantavirus prevalence in small mammal assemblages at the site, region, continental, hemisphere, and global levels; 2) to compare and contrast differences in prevalence found in sylvan and disturbed habitats; 3) investigate the relationship between phylogenetic diversity and seroprevalence; 4) to develop predictive models for hantavirus prevalence in small mammal assemblages using defined ecological correlates; and 5) to quantify transmission events and seroconversions between naïve and infected rodents.  Preliminary results suggest a relationship between the weighted site seroprevalence and the relative species abundance, observed species richness, and phylogenetic relatedness of species within the assemblage.   Current research regarding hantavirus disease dynamics usually follows outbreaks of hantaviral disease in localized areas.  My research aims at understanding the small mammal assemblage components and climatic factors influencing hantavirus prevalence, and developing a means of preventative surveillance. 


    Matthew T. Milholland received his B.S. in biology in 1996 from Abilene Christian University and studied integrative physiology at The University of North Texas Health Science Center at Fort Worth before obtaining his M.S. in wildlife ecology from Texas State University in 2005.  He was a lead biologist studying the impacts of windfarms on bat and bird mortalities in Abilene, TX.  He has also worked as a contract biologist throughout Texas and as an adjunct instructor at Cisco College before beginning the Ph.D. Aquatic Resources program at Texas State in January 2013.  He and his wife of 19 years, Megan, have two children, Noah (9) and Posey (7), of whom he is very proud.


  • Dissertation Proposal Defense


    Characterization of chromatin dynamics under biotic stress in Arabidopsis


    Name: Yogendra Bordiya

    Major Advisor: Dr. Hong-Gu Kang        

    Committee Members: Dr. Nihal Dharmasiri,Texas State University, Dr. Sunethra Dharmasiri,Texas State University, Dr. Daniel F. Klessig, Cornell University, Dr. Ping He, Texas A&M University

    Friday, January 16, 2015, 10:00 AM, Supple 257-A


    A genetic screen for components involved in resistance (R) protein-mediated immunity in Arabidopsis led to isolation of crt1 (compromised recognition of TCV). CRT1/MORC1 was shown to be a MORC ATPase that physically interacts with multiple immune components. While MORC1 is mainly located in endosome-like vesicles in the cytoplasm, a subpopulation resides in the nucleus, which increases after infection. The combined findings that MORC1 i) is an endonuclease, ii) is localized to heterochromatin, and iii) is implicated in epigenetic regulation, including suppression of heterochromatic transposable elements (TEs), suggest that MORC1 has an important nuclear function(s). To gain insight into the role of MORC1 in the nucleus, genome accessibility in response to Pseudomonas syringae pv. tomato (Pst) in Arabidopsis and its MORC1-associated mutants were assessed. DNase-seq, a genome-wide inspection of DNase I hypersensitive site (DHS), identified 29,450 DHS in twelve different combinations of genotypes and treatments including Pst infection. Characterization of the DHS differentially present among these different combinations revealed that genomic regions associated with signal transduction and (a)biotic stress are over-represented, under pathogen challenge. TEs were also significantly over-represented in Pst infection-induced- and MORC1 mutant-associated differential DHS (dDHS). Interestingly, these TE-associated dDHS were primarily in heterochromatic region for the MORC1 mutants but genome-wide for Pst infection-induced dDHS. Interestingly, chromatin immunoprecipitation of MORC1 showed that, while MORC1 indeed interacted with these heterochromatic TE-associated dDHS, it interacted with Pst infection-induced TE-associated dDHS that are located in well-characterized defense marker genes including PR-1 during pathogen infection. These results suggest that infection drives dynamic changes in the genome and that MORC1 plays important roles in modulating accessibility to these genomic regions. 


    Yogendra received his bachelor’s degree in Agriculture from University of Agricultural Sciences, Bangalore, India in 2009 and master’s in Crop Science and Biotechnology in 2012 from Seoul National University, Seoul, South Korea. In 2012 Fall, Yogendra entered into Ph.D. program at Texas State University.



    Thesis Defense


    DEVELOPMENT OF 2-D AND 3-D PAPER-BASED MICROFLUIDIC DEVICES FOR THE DETECTION OF CRYPTOSPORIDIUM AND GIARDIA


    Shalini Madadi

    Major Advisor: Dr. Shannon Weigum

    Committee Members: Dr. Rohde, Dr. McLean

    Monday, December 8, 2014 10:00 AM - Norris Conference Room


    In developing countries, morbidity due to infectious diseases such as diarrheal illness can cause major deterioration of physical and cognitive impairment in young children under the age of five and individuals with poor immune system. In such regions, proper diagnosis and treatment can help in changing the mortality and morbidity rates. Current tests used to detect diarrhea-causing pathogens are often expensive, time consuming, require a well-maintained centralized laboratory with continuous power supply, highly skilled laboratory personnel and good bio-safety practices, which are often limited in resource poor settings in both developed and developing countries. Real-time PCR, immunoassays (ELISA, or EIAs, lateral-flow test strips), microscopy, and flow cytometry are few examples of traditional tests available. The goal of this project was to develop a paper-based microfluidic device for detection of Cryptosporidium and Giardia, two protozoan pathogens that cause persistent to chronic diarrhea worldwide that is inexpensive and easy to use. Toward this goal, we have designed and optimized a wax-printing technique to create microfluidic channels in paper that direct fluid flow via capillary action in defined patterns for colorimetric immunoassay detection of individual and multi-plexed pathogens. Initial results suggest that a minimum printed width of 300 µm is necessary to form an impermeable barrier in chromatography paper when heated at 95oC for 10 min, while a minimum channel width of 1500 µm is necessary to wick fluids through the microfluidic channels. Next, we performed a concentration series of immunolabeled Cryptosporidium oocysts and Giardia cysts to determine the lowest detectable number of oocysts in an enzyme-based colorimetric assay. Our results indicate that as few as 250 oocysts are detectable for Cryptosporidium and 2000 cysts for Giardia. We further fabricated 3- dimensional (3-D) paper-based devices with a size-selective filter that excludes the use of cumbersome pre-labeling protocol and expensive equipment to remove unbound-free antibodies by retaining enzyme-bound pathogens and measuring the amount of enzyme that reaches the bottom layer. Tests for size-selective membrane and 3-D retention assay using in-line filter holder proved that cellulose acetate membrane with 1.2 µm pore size had shown to retain Cryptosporidium oocysts of size 4-6 µm. Follow-up assays for detection of cryptosporidium in paper devices using enzyme retention assay showed potential for further improvement in development of paper-based microfluidic devices. This research supports the use of paper-based microfluidic assays for colorimetric detection of infectious pathogens with high sensitivity that use low cost materials and simple fabrication techniques


    Bio:  Shalini Madadi was born and raised in Hyderabad, India where she pursued her bachelor’s degree in biotechnology in 2010. Coming from a developing country, she has seen the poverty and limited access to health care resources in remote areas where infectious diseases are prevalent, which inspired her to pursue a degree in master’s under the supervision of Dr. Weigum. Her research aims towards developing inexpensive and easy-to-use diagnostics that can identify infectious diseases, such as pathogens causing diarrhea, using simple colorimetric assays.


    Thesis Defense

     

    EFFECTS OF LANDSCAPE CHARACTERISTICS ON NESTING ECOLOGY OF CAVITY-NESTING BIRDS


    Sara E. Harrod

    Major Advisor:  Dr. Clay Green             

    Committee Members: Dr. Floyd “Butch” Weckerly, Dr. Thomas “Randy” Simpson

    Friday, November 21, 2014 - 3:30 PM, SUPP 153A


    I studied the effects of landscape characteristics on nesting success and nest site selection of native cavity-nesting birds utilizing nest boxes at the Freeman Center, San Marcos, Texas from 2013 to 2014.  Nest checks were conducted twice weekly from February to July of each year.  Landscape analyses were conducted using ArcGIS and FRAGSTATS and habitat measurements were collected on site to examine the landscape characteristics surrounding each box.  I used the Mayfield Method to estimate nest success of each nesting pair.  For each year, Principal Components Analyses (PCA) were conducted to assess characteristics of each nest box, and Canonical Correspondence Analyses (CCA) were conducted to assess relationships between habitat features surrounding nest sites and species nesting success. 

    Four species utilized the nest boxes in 2013, followed by six in 2014.  In 2013, Eastern Bluebirds (Sialia sialis) (15% occupancy) and Ash-throated Flycatchers (Myiarchus cinerascens) (5% occupancy) were most successful in grassland and shrubland habitats, respectively.  Bewick’s Wrens (Thryomanes bewickii) (77.5% occupancy) were generalists; their nesting success showed no association for any habitat variable.  Sites of Black-crested Titmice (Baeolophus atricristatus) (12.5% occupancy) nests were associated with areas of little herbaceous or woody vegetative cover while no difference in landscape characteristics were found between successful and failed nests.  In 2014, bluebird (20% occupancy) success and failure were associated with large grassland patches.  Flycatcher (11.7% occupancy) success was not associated with any measured habitat variables, while failure occurred in sites with large shrubland patches.  Titmouse (38.3% occupancy) success and failure were not correlated with any measured habitat variables, while wren (71.7% occupancy) success was most likely to occur in sites with large woodland patches.  To maximize nesting success, wildlife managers utilizing nest boxes to manage for a given species should consider not only habitat types but patch characteristics such as density and area when considering where to erect nest boxes. 


    Bio:  Sara Harrod was born in Wichita Falls, Texas, on October 05, 1989.  Her interest in wildlife began at a young age and led to a passion for bird-watching.  After graduating from high school, she attended Texas A&M in College Station, Texas, and began her undergraduate work.  She received a Bachelor of Science in Zoology in May of 2012.  The following fall, she began her work on her Master’s at Texas State University.  In the future Sara hopes to study the effects of anthropogenic activity on passerines and the conservation of at-risk populations. 


    Thesis Defense


    RELATIONSHIP BETWEEN BASE FLOW MAGNITUDE AND SPRING FISH COMMUNITIES


    Cody A. Craig

    Major Advisor:  Dr. Timothy H. Bonner     

    Committee Members:  Dr. Christopher Taylor (UTPA), Dr. Floyd Weckerly (TxState)

    Friday, November 21, 2014 - 10:00 AM,  FAB 130


    Base flow is the portion of stream flow attributed to groundwater, and few studies quantify the pure effects of base flow reductions on stream fish communities. Spring complexes within the karst terrains of the Edwards Plateau Region of central Texas offer a unique opportunity to test hypothesized relationships between base flow and stream fish communities. Spring complexes are numerous within the Edwards Plateau, providing multiple independent observations, stable hydrographs dominated by base flow conditions, similar groundwater sources, and support endemic fishes that are associated with the spring complexes (i.e., spring-associated fishes).  Primary objectives of this study were to assess spring-associated fish richness, relative abundances, and densities across a gradient of base flow magnitudes with predictions that metrics of spring-associated fish communities would linearly decrease with reductions in base flow.  To control potential confounding variables, additional objectives were to test for the presence and strength of parapatry that is hypothesized to exist between spring-associated fishes and riverine-associated fishes (i.e., fishes with distributions not typically associated with spring complexes).  Patterns in richness, relative abundances, and densities indicated parapatric distribution between spring-associated and riverine-associated fishes.  Strength of parapatry depended upon base flow magnitude.  Correspondingly, differences in spring-associated fish richness, relative abundances, and densities along a base flow gradient were detected, but only densities were linearly related to base flow.  Richness and relative abundances of spring-associated fishes were non-linearly related to base flow, suggesting that spring complexes have a level of buffering capacity against base flow reductions.  The relationship between spring-associated fish communities and base flow gradient was used to support the reported parapatry between spring-associated fishes and riverine-associated fishes with in the area and to highlight the conservation value of spring complexes to regional fauna.  Predictive models generated in this study can be used to evaluate spring-associated fish community integrity within the Edwards Plateau Region and to predict future changes in Edward Plateau spring complexes related to increases in groundwater extraction.


    Bio:  Cody Craig was raised in Longview, TX.  He attended Texas Tech University for his B.S. in Wildlife Fisheries Management.  Continuing his undergraduate research, he joined the graduate program at Texas State for a M.S. in Aquatic Biology.  After graduation, he would like to continue his educational pursuit with a Ph.D. with an ultimate goal of continuing research in the field of aquatic ecology.  


    Thesis Defense


    OCCURRENCE AND AMOUNT OF MICROPLASTICS INGESTED BY FISHES IN WATERSHEDS OF THE GULF OF MEXICO


    Melissa B. Phillips

    Major Advisor:  Dr. Timothy H. Bonner (Biology)

    Committee Members:  Dr. Gwendolyn Hustvedt (Fashion Merchandising), Dr. Joseph A Veech (Biology)

    Thursday, November 20, 2014 - 10:00am, FAB 130


    Occurrence and types of microplastics in the digestive system of freshwater fishes could be an emerging environmental crisis because of the proliferation of plastic pollution in aquatic environments.  Recent studies report increasing amounts of microplastics in marine systems and in the gut tracts of marine fishes.  To date, only one study has reported percent occurrence of microplastics (12%) in the digestive system of freshwater fishes.  Purposes of this study were to quantify occurrences and types of microplastics ingested by fishes within the western freshwater drainages of the Gulf Mexico and an estuary of the Gulf of Mexico.  My study objectives were (1) to enumerate and identify microplastics from fishes taken from 10 sites and nine freshwater drainages of Texas and harbor, bay, and gulf sites within or near the Laguna Madre of southeast Texas, (2) to compare percent occurrence of microplastics among habitat and trophic guilds of fishes, and (3) to compare percent occurrence of microplastics between urbanized and non-urbanized streams and thus test the hypothesis that fishes from urbanized streams will have greater percent occurrence of microplastics than fishes from non-urbanized streams.  Among 535 fishes examined in this study, percent occurrence of microplastics was 8% in freshwater fishes and 10% in marine fishes.  Plastic types included polyester, polystyrene, polypropylene, acrylate, and nylon. Percent occurrence of microplastics ingested by fishes in non-urbanized streams (5%) was less than that of one urbanized streams (Neches River; 29%).  Percent occurrence by habitat (i.e., benthic, pelagic) and trophic guilds (herbivore/omnivore, invertivore, carnivore) were similar.  Percent occurrences of microplastics reported herein are similar for freshwater fishes and towards the lower end of the range of microplastic ingestion in marine fishes (range: 8 - 33%).  Occurrences of microplastics in the fishes pose several environmental concerns.  For fish health, microplastics absorb toxins and can be passed through the digestive system, into the circulatory system, and accumulate in tissue.  Long-term effects are unknown for the fish or the effects on human consumers. 


    Bio: Melissa Phillips was raised in London, England.  She attended the University of Leeds for her B.A. in Sociology.  After raising enough funds to she took a one way flight to Honduras where she certified as a Divemaster and dived her way around Central and South America.  Upon returning to London she worked in Marine Conservation and web development.  She enrolled in the MS-Sustainability Studies program to further a career in marine conservation, specifically to reduce the amount of plastic pollution in our marine environments.  


    Dissertation Defense

     

    Freshwater turtles as a renewable resource: using red-eared slider

    (Trachemys scripta elegans) as a model species


    Ivana Mali


    Major Advisor: Dr. Michael R.J. Forstner            

    Committee Members: Dr. Thomas R. Simpson, Dr. Floyd W. Weckerly, Dr. Scott K. Davis, Dr. Hsiao-Hsuan Wang

    Thursday, November 20, 2014 - 2:00 pm LBJ 3-9.1


     Freshwater turtles have a long history of being utilized by humans. For centuries, turtles have been used as a protein resource and in traditional medicine, playing an important role in cultures across the globe. Wild turtle harvests have historically and currently been unsustainable. While some regulatory regimes have been implemented in different regions, many taxa remain unprotected and there is a need for improvement. The objective of this work was to assess the problem of unsustainable wild freshwater turtle harvest and commercial trade in the United States of America (US), focusing first on the entire southeast region and specifically on the Texas harvest paradigm. I also evaluated solutions, such as commercial turtle farming as an alternative to wild population harvest. The results provide evidence of large, unsustainable exports of freshwater turtles continuing out of the US, despite recently implemented restrictions on turtle harvest in several states of the Southeast US. Moreover, I provide evidence of the negative consequences from non-uniform harvest regimes across the Southeast US. Turtle harvest regulations in Texas are based on assumptions regarding the overland movement patterns of adult red-eared slider ( Trachemys scripta elegans) on the landscape. To test these assumptions, I developed a novel method to monitor movements, achieving a higher resolution than what has been previously reported and allowed me to evaluate the source-sink harvest paradigm applied to Texas freshwater turtle populations. The results illustrate flaws in the current management regulations, but also provide direction for future studies to help improve management. Finally, by modeling biological data alongside economic information on farming red-eared sliders in Louisiana, I demonstrated the economic challenges of farming red-eared sliders for meat markets. While it gives a perspective of how the future market may develop, it highlights some of the difficulties to achieving sustainability with the commercial trade of turtles for meat.

    Bio: Ivana Mali was born in Novi Sad, Serbia on February 25 1983 to Ljiljana and Petar Mali. She obtained her Bachelors of Science in Biology at Henderson State University in May 2008. She enrolled at Texas State University in 2008 and earned her Masters of Science in Wildlife Ecology in August 2010. She entered the Aquatic Resources doctoral program in 2010 focusing on chelonian population sustainability. She has been a Flowing Waters teaching fellow (2011-2013) and is the current president of the Texas Herpetological Society. Her research topics include freshwater turtle reproductive ecology, testing field sampling assumptions and biases, movement ecology, but also global freshwater turtle sustainability under anthropogenic pressures such as road mortality and commercial harvest.


    Dissertation Proposal Defense


    Biodiversity Research using Hierarchical Models in a Bayesian Framework


    Katherine Bell


    Major Advisor: Dr. Chris Nice       

    Committee Members: Dr. James Fordyce, Dr. Darrin Hulsey, Dr. Noland Martin, and Dr. James Ott

    November 13, 2014 - 9:00 am, LBJ Student Center 3-9.1


    Biological systems are structurally complex, but hierarchical modeling allows these multiple levels of structure to be examined simultaneously. The research I propose explores the use of hierarchical models in three different biodiversity research projects: 1.) I will investigate the population genomics and genomic architecture of jaw morphology in a trophically polymorphic species of cichlid. Here a hierarchical approach will be used to model uncertainty, which results from next generation sequencing techniques, and to test for associations between phenotype and genotype. 2.) Next, I will examine the response of British butterflies to climate change.  For this question a hierarchical model will enable the simultaneous estimation of both species- and community-level responses to climate change. 3.) The third project explores the fitness surface of chemical sequestration using the pipevine swallowtail butterfly as a model system. This project will include lab and field studies which will provide data used to develop a hierarchical model that accounts for costs and benefits in fitness to both predators and prey. 


    Bio: Katherine was born in Dorset, England. She received a BSc HONS in Zoology from Queen Mary, University of London in 2009. In 2010 she enrolled at Texas State University and joined the Population and Conservation Biology program, as a part of Chris Nice’s lab. Upon completion of her Masters in 2012 she joined the PhD program in Aquatic Resources at Texas State University and continued her work with Chris and the Nice lab group.


    Thesis Defense

     

    DIETARY ANALYSIS OF OVERWINTERING POPULATIONS OF BRAZILIAN
    FREE-TAILED BATS (TADARIDA BRASILIENSIS) IN

    CENTRAL TEXAS, UNITED STATES


    Lynsey Ramirez


    Major Advisor:  Dr. Thomas R. Simpson           

    Committee Members: Dr. Clay Green, Dr. Chris Nice

    Monday, November 10, 2014 - 9:00 am, Norris Conference Room


    Brazilian free-tailed bats (Tadarida brasiliensis) overwinter in south and central Mexico and migrate north each spring to form large breeding colonies in northern Mexico and the southwestern United States; however, there are recent observations of increasing populations of free-tailed bats overwintering in central Texas.  It is possible that climate change has led to warmer winters in northern sections of their range with increased insect productivity forming a sustainable food resource for the bats.  Dietary analysis using the dissecting microscope methodology show their summer prey includes adults of several Lepidopteran species in the family Noctuidaie and species of beetles in the order Coleoptera.  In this study I used traditional methodology of dissecting guano pellets to identify insect fragments through the use of various keys, guides and experienced entomologists, and gather information on the dietary habits of overwintering free-tails.  Pellets were collected from roosting sites at three different locations across central Texas: the Chiroptorium, Old Tunnel, and D’hanis Bridge, and then dissected in the lab.  Orders of the insects and in some cases, families, were identified which determined a glimpse of what free-tailed bat colonies are eating to survive winter months in central Texas.  Diptera, Hemerobiidae, and Lepidoptera composed the greatest percent composition of diet with significant differences between sites based on a particular food category.  Differences could be due to diverse vegetation and habitats at each sampling site.  Winter diets will begin to be established and understanding the factors that control migratory dynamics and alterations expected with continuing climate changes can be gained.


    Bio:  Lynsey Martinez Ramirez was born in Alamogordo, New Mexico on August 13, 1987 to Jose and Patricia Martinez and raised in San Antonio, Texas.  She graduated with a B.S. in Biology at the University of Texas at San Antonio May of 2010 and enrolled at Texas State University-San Marcos to pursue a Master’s of Science degree in Wildlife Ecology.  Lynsey was married in 2011 and had two baby girls in 2012 and 2013.  During the course of her graduate career, she was actively involved with Hermandad de Sigma Iota Alpha, Incorporada and earned a hunting scholarship with Conservation Leaders for Tomorrow.  She was also an Instructor’s Assistant for Freshman Biology (non-majors) and a member of TriBeta National Biological Honor Society and the Texas Academy of Science.  Lynsey hopes to use her degree to pursue work in conservation biology and restoration projects.


    Thesis Defense


    EXAMINATION OF A DNA APTAMER (TLS11a) AS A CANCER-SPECIFIC

    TARGETING AGENT WITHIN CULTURED MEAR LIVER CANCER CELLS


    Melissa D. Sutton

    Major Advisor:  Dr. Shannon Weigum     

    Committee Members:  Dr. Tania Betancourt, Dr. Dana García

    Friday, November 7, 2014 - 10:00 am,  RFM 4233


    Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death worldwide, particularly in regions where chronic Hepatitis B and C infections are common.  Early detection of HCC remains challenging due to the lack of existing biomarkers with adequate sensitivity and specificity for screening high-risk patients.  Nanoparticle assemblies that incorporate high-affinity aptamers which specifically bind malignant hepatocellular carcinoma cells could be useful for targeted drug delivery or enhancing contrast with existing ablation therapies.  The in vitro interactions of a tumor-specific aptamer, TLS11a, were characterized in a hepatoma cell line via live-cell fluorescence imaging, SDS-PAGE and Western blotting techniques.  Cell surface binding of the aptamer-AlexaFluor®546 conjugate was found to occur within 20 minutes of initial exposure, followed by internalization and localization to late endosomes or lysosomes using a pH-sensitive LysoSensor Green dye and confocal microscopy. In an effort to characterize the TLS11a target protein, the TLS11a/AlexaFluor-546 conjugated aptamer was used in place of primary antibody in a conventional Western blot following electrophoresis and transfer of proteins extracted from various cellular components.  Prominent bands appeared just over 21 kilodaltons (kDa) in the cell surface protein fraction, the cytosolic hydrophilic protein fraction and in whole cell lysates; no TLS11a-bound protein bands were apparent in the hydrophobic membrane fraction.  Aptamer-functionalized polymer nanoparticles containing poly(lactic-co-glycolic acid) (PLGA) and poly(lactide)-b-poly(ethylene glycol) (PLA-PEG) were then prepared by nanoprecipitation and passively loaded with the chemotherapeutic agent, doxorubicin, yielding spherical nanoparticles approximately 50 nm in diameter.  Targeted drug delivery and cytotoxicity was assessed using live/dead fluorescent dyes and a MTT colorimetric viability assay with elevated levels of cell death found in cultures treated with either the aptamer-coated and uncoated polymer nanoparticles.  Identification and characterization of the cell surface protein epitope(s) recognized by the TLS11a aptamer are ongoing along with nanoparticle optimization, but these preliminary studies support continued investigation of this aptamer and functionalized nanoparticle conjugates for targeted labeling and drug delivery within malignant hepatocellular carcinomas.


    Bio:  Melissa Sutton was raised in Virginia Beach, Va. and moved to Texas in 2008.  She briefly attended Austin Community College where she received her A.S. in Chemistry, before transferring to Texas State for her B.S. in Microbiology.  Continuing her undergraduate research, she joined the graduate program at Texas State for a M.S. in Biology.  After graduation, she would like to have a career in industry, either working in a lab or a research facility.


    Thesis Defense

     

    Effects of diel cycle and turbidity on antipredator response to multiple cues of predators by Eurycea nana and Eurycea sosorum.


    Kristina Zabierek

    Major Advisor:  Dr. Caitlin Gabor           

    Committee Members: Dr. Jim Ott, Dr. Kristen Epp

    Friday, October 31, 2014 - 1:30 pm, SUPP 153-A


    Predation is an influential force in many ecological communities. Prey often exhibit antipredator behaviors which minimize risk of predation. However, antipredator behavior may be costly by reducing time spent foraging or mating. I wanted to determine whether Eurycea nana, the San Marcos salamander, is able to minimize costs of antipredator behavior by responding to chemical cues of predators based on the diel cycle of the predator. I studied response of salamanders to a diurnal predator, green sunfish (Lepomis cyanellus) and a nocturnal predator, red-swamp crayfish (Procambarus clarkii) during the daytime and nighttime to determine if salamanders were able to respond in a risk-sensitive manner. I found that salamanders exhibited increased antipredator behavior in response to green sunfish, but not to crayfish. I also found that diel cycle did not affect antipredator behavior, suggesting they do not respond in a threat sensitive manner based on the foraging cycle of their predator.

                Anthropogenic influences can have effects on predator-prey interactions. Increased turbidity is a growing problem for aquatic systems and can affect the ability of prey to respond to predators. I studied the effect of turbidity on antipredator behavior in Eurycea sosorum, the Barton Springs salamander, by comparing their response to cues from green sunfish predators, Lepomis cyanellus, and green-throat darter non-predators, Etheostoma lepidum. I wanted to determine whether multimodal cues are important in predator detection, therefore cue treatments included a fully crossed design including both chemical and visual cues of the predator and non-predator across two vision levels; clear (0 NTU) and low turbidity (~20 NTU). I found that E. sosorum significantly increased antipredator behavior to predator chemical cues compared to non-predator chemical cues but did not respond to visual cues. This suggests multimodal cue use is not a major factor in predator detection. We also found that E. sosorum had decreased antipredator behavior in turbid conditions compared to clear conditions. This has significant conservation implications for the already endangered salamander.


    Bio: Kristina was raised in Brooklyn, New York and received her B.A. in Biology at CUNY Queens College in 2012. During her time there she worked in a research laboratory studying costs of pesticide resistance in the Colorado potato beetle. She spent a summer on a farm in Ithaca, NY studying organic farming methods to attract natural predators of the Colorado potato beetle. Interested in conservation, Kristina also had an internship with the NYC Parks Department monitoring piping plovers. Always being interested in amphibian biology, Kristina joined the Population & Conservation Biology under Dr. Gabor in 2013. During her graduate education Kristina participated in projects examining anthropogenic effects on stress hormones (CORT) in Eurycea nana and Eurycea tonkawae. After completion of her M.S. degree, Kristina plans to dedicate herself to pursuing knowledge about insect-amphibian interactions and to conservation education.


    Thesis Defense

     

    The impact of human disturbance on the foraging ecology of Green Herons (Butorides virescens)


    Amanda A. Moore     

    Major Advisor:  Dr. M. Clay Green

    Committee Members: Dr. David Huffman, Dr. Thomas “Randy” Simpson

    Friday, October 31, 2014 - 10:00 am, RFM 4233


    As the trend towards urbanization continues, natural areas can become highly urbanized and recreational use of these natural areas may also increase. Waterbirds use areas that are generally subject to elevated levels of human disturbance and consequently are often considered highly susceptible to disturbance. In 2013 and 2014, I assessed the effects of human recreational disturbance on Green Herons (Butorides virescens) through the use of focal observations. I collected behavioral data over 154 observations along the headwaters of the San Marcos River located in Central Texas; the river varies in its degree of human recreational activity and thereby disturbance varied across sites. I built 15 linear regression models to assess the potential influence of human disturbance as well as potential influence of habitat differences between study sites on each of the response variables (4 foraging behaviors and foraging efficiency).

    Using AIC model selection, I found that differences in habitat provided the best explanation for the observed variation in 4 of the 5 response variables measured. These results suggest that Green Heron foraging behavior is not significantly affected by human recreational disturbance but influenced more by differences in habitat. It is possible that the birds are habituated to disturbance and tolerant of humans at certain locations and perhaps only modify their foraging technique in order to maximize their foraging efficiency to suit their locale. These finding are noteworthy in that it is important to be able to distinguish cases where human disturbance impacts a species from cases where it does not in an ongoing effort to strike a balance between the needs of waterbird species and human recreational use of aquatic systems.


    Bio: Amanda Moore was raised in Bloomingdale, Illinois and moved to Texas in 2001. She received a B.A. in Arts & Technology from U.T. Dallas in 2005. After graduation, Amanda worked out in the “real world” for about 5 years before deciding to change paths and move to San Marcos to join the Texas State Wildlife Ecology graduate program. She hopes her next “real world” career involves conservation, fieldwork, and birds.


    Thesis Defense


    Floral Scent Production in the Carrion Flower Genus Stapelia (Apocynaceae)

    Johann Souss

    Major Advisor: Dr. David Lemke             

    Committee Members: Dr. Michael A. Huston, Dr. Garland Upchurch

    Thursday, October 30, 2014 - 1:00 pm, Norris Conference Room


                Floral scent plays an important role in the reproductive biology of many flowering plants, often serving as a pollinator attractant. In a majority of species, floral scent is a diffuse product of the epidermis, especially that of the corolla. In some groups, however, the production and emission of the volatile substances responsible for fragrance is localized to specialized glands, temed osmophores. This study examined the composition of floral fragrance in the genus Stapelia, a group of succulent perennial herbs native to the drier regions of South Africa. Volatile compounds produced by flowers were collected using headspace-solid phase microextraction. Component separation and identification were achieved using gas chromatography-mass spectrometry. A diversity of organic compounds was found among members of the genus, including various terpenoids, organic acids, sulfur compounds, and nitrogenous compounds. Among the most common compounds identified were dimethyl disulfide, dimethyl trisulfide, hexanal, and trimethylamine. Although osmophores were originally described from the petals of other members of the milkweed family, this study has demonstrated, using a combination of vital staining, histological examination, and gas chromatography, that among Stapelia species the production of volatile compounds appears to be a function of the corona, the often elaborate set of appendages situated between the corolla and androecium.


    Bio: Johann Souss received his B.S. in zoology from University of Florida in 2008.  Upon completing his undergraduate degree he worked as a resident naturalist in Costa Rica.  He joined the Texas State biology graduate program in 2010.  He moved to Oregon in 2012, where he spent most of his time exploring his interests in coffee and hospitality.  Johann will be departing for Tanzania in February 2015 to work on sustainable agriculture and environmental education projects as a Peace Corps Volunteer.

     


    Thesis Defense


    Examining the effects of urbanization on the occurrence of mammal species

    in natural areas of the eastern Edwards Plateau

     


    Matt Haverland

    Major Advisor:  Dr. Joe Veech           

    Committee Members: Dr. Butch Weckerly, Dr. Jennifer Jensen (Geography)

    Thursday, October 30, 2014 - 10:30 am, Norris Conference Room


    Central Texas is experiencing urbanization at an unprecedented rate. This anthropogenic conversion of land is due in part to a rapidly growing population in the Austin and San Antonio metro areas and the development of infrastructure and resources needed to support that growth. Urban parks, greenspaces, and preserves can mitigate the impact of land development by serving as habitat for local wildlife populations. To maximize the potential of this habitat, we must assess how urbanization influences species across a landscape. Mesocarnivores act as top-tier predators in an ecosystem almost completely devoid of large predators and thus they could influence abundance of other species. I surveyed 72 sites (point locations) across nine different study areas throughout the eastern Edwards Plateau ecoregion of central Texas for fourteen survey occasions during 2013. Using occupancy modeling, I examined the influence of ten different urban covariates on mesocarnivore occurrence. Generalist species, such as raccoons and opossums, had an increased probability of occurrence at sites with higher urban influence and were most likely to occur in smaller more urban study areas. Ringtails and grey foxes appeared to be unaffected by urbanization and were equally likely to occur across all sites. Results for other species, such as the coyote and skunk, were inconclusive. Most species had very low probability of detection with only the raccoon and fox having a probability greater than 0.1.  Knowledge of the effect of urbanization on wildlife could assist us in evaluating current preserves as well as devising strategies to conserve species in any planned future preserves.


    Bio: Matthew Haverland was raised in College Station, Texas and received his B.S.  in Marine Fisheries at Texas A&M University-Galveston in 2007. During his time in Galveston, he worked as a student research assistant for the NOAA Fisheries Ecology Lab aiding biologists in studies on benthic marsh communities in Texas and Louisiana. After graduation, Matt joined the NOAA Fisheries Service as a temporary fisheries observer collecting data on bluefin tuna spawning in the Gulf of Mexico and later joined the Pelagic Observer Program as a full time fisheries observer where he worked for several years. After a renewed interest in terrestrial biology, Matt joined the Texas State Wildlife Ecology graduate program in 2012. During his graduate education, Matt has participated in several ecological studies including work as a seasonal field technician conducting bobwhite quail surveys. After completion of his M.S. degree, Matt plans to seek employment as an ecologist examining vertebrate communities and ways to mitigate the impact of human development.


    Dissertation Proposal Defense

     

    Probiotic regulation of fat-storage via Angiopoietin-like 4 (ANGPTL4)


      Priscilla Pham


      Major Advisor:  Dr. Bob McLean           

      Committee Members: Dr. Dana García,  Dr. Shannon Weigum, Dr. Dhiraj Vattem,

      Dr. Jennifer Spinler, Dr. Vatsala Maitin

      October 17, 2014 - 11:00 am, SUPP 153-A


    Gut bacteria have been shown to influence diet-related obesity, mediated in part via ANGPTL4, a       circulating lipoprotein lipase inhibitor that modulates fat-storage in the adipose tissue. Modulating the gut microbiota to exert stimulatory activity towards ANGPTL4 may thus serve a protective function against diet-related obesity. I have screened several commonly used probiotic strains for enterocytic ANGPTL4-modulation in vitro and observed significant increases in ANGPTL4 protein levels in response to secreted factors from Bifidobacterium longum. An initial characterization of these bioactive factors indicated them to be secreted B. longum proteins. The objective of the proposed study is to further elucidate the mechanism of ANGPTL4-regulation by B. longum and its impact on fat storage, and investigate if dietary enrichment of Bifidobacterium in the gut can enhance ANGPTL4 in human subjects.


    Bio:  Priscilla Pham is from Houston, Texas and received her BS in Human Nutrition and Foods from Prairie View A&M University. In 2010, she entered the Master’s in Human Nutrition Program at Texas State University and began her research in the Molecular and Cellular Nutrition Laboratory under Dr. Vatsala Maitin. As a PhD student, she is continuing her research work under the advisement of Dr. Bob McLean.


    Thesis Defense


    Species traits versus environmental properties as factors

    influencing species abundance


    Stephanie Miller

    Major Advisor:  Dr. Joe Veech           

    Committee Members: Dr. Jim Ott, Dr. Ivan Castro-Arellano

    Tuesday, October 21, 2014 - 12:30 pm, SUPP 257-A


    A longstanding goal in ecological research is to explain the abundance of a species found in a particular place and time. To do so, researchers identify factors that influence species abundance and attempt to describe their relationships quantitatively. The main objective of my study was to compare the relative effects of intrinsic species traits (morphological, physiological, behavioral and life history attributes) and extrinsic environmental properties (climatic, biotic and geographic aspects) on species abundance. From a literature search, 915 independent abundance observations were compiled for 83 species from 170 survey locations distributed throughout the western United States. Besides abundance information, data on species traits associated with body size, reproductive capacity, diet, and geographic range were acquired along with properties of each survey location including climatic, spatial, and biotic (number of other rodent species and individuals) variables. To make the comparison, four composite variables (an intrinsic ecological variable, intrinsic geographic variable, extrinsic abiotic variable and extrinsic biotic variable) were created using Principal Components Analysis (PCA), and a fifth variable that was the distance between each species location (occurrence in a particular survey) and the center of that species geographic range was also included. Model comparison and model-averaging procedures were then conducted using all 31 possible linear regression models of the five predictor variables with standardized abundance (corrected for extraneous design variables) as the response variable. For the dataset consisting of all species, the intrinsic ecological variable was found to have the greatest influence on abundance (N=915, βeco = 0.116, SE= 0.042). For datasets limited to certain genera (Dipodomys, Neotoma, Perognathus, and Peromyscus), different variables were identified as most influential. These results indicate that environmental properties and species traits can influence abundance independently and in combination with one another. Moreover, there is no single combination of extrinsic and intrinsic variables that most influences abundance in all genera. Nonetheless, the distinction between intrinsic and extrinsic variables is a useful dichotomy in studying the factors affecting species abundance.


    Bio: Stephanie received her Bachelors of Science from the University of Florida in 2010, with a major in Zoology and a minor in Wildlife Ecology and Conservation. During her undergraduate career she worked in a physiology lab studying the response of snake kidneys to salinity changes and an animal behavior lab that studied the effects of predation on cichlid parenting structure. Upon completing her undergraduate degree, Stephanie acquired a field technician position working for a Clemson University Ph.D. student examining the habitat use of coyotes and raccoons on Yawkey Wildlife Preserve. Now after completing her Masters at Texas State University in Population and Conservation Biology, she plans to continue her education studying topics at the intersection of community ecology, species distribution, and biodiversity conservation.


    Dissertation Proposal Defense


    Personality, predation, and competition in a changing environment


    Chelsea Blake


    Major Advisor: Caitlin Gabor , Biology Department, Texas State University             

    Committee Members: Dr. Andrea Aspbury, Biology Department, Texas State University, Dr. Alison Bell, University of Illinois-Champagne-Urbana, Dr. Brian Langerhans, North Carolina State University, Dr. Chris Nice, Biology Department, Texas State University  

    Sept 4, 2014 - 12:00 noon, HPB 145


     In order to explore the effects of anthropogenic environmental change on the behavioral ecology of native species, I propose four studies which will examine a range of predatory and competitive relationships. I present a study examining how personality of native prey individuals influences their behavior and survival of several different predator species, including native, novel, and invasive predators. In a second study, I will examine the relationship of behavioral traits to body shape traits associated with predator escape ability, and plasticity of behavior in response to morphological changes. I will also explore how personality of prey may relate to predator recognition in response to a novel predator. In the final study I will explore how environmental changes like rising turbidity can interact with competitive and predatory relationships among native species. The goal of the experiments presented is to add to our understanding of how behavior interplays with anthropogenic changes to shape outcomes for native species in shifting ecological landscapes.


    Bio: Chelsea Blake grew up in the heart of the Midwest. Chelsea double majored in Art and Biology at Earlham, a Quaker liberal arts college in Indiana. After gaining teaching, field work, and research experience in Maryland, Oregon, Georgia, and South Carolina, she moved to Texas in 2011 and entered the Aquatic Resources PhD program at Texas State. She received a National Science Foundation Graduate Research Fellowship in 2013 to support her dissertation work. She lives in Austin with a houseful of pets, roommates, and her husband. She legally married her partner (and best field assistant) while in New York this summer.

     


  • Thesis Defense

     

    The effect of indole production on the growth of Escherichia coli when co-cultured with Enterococcus faecalis


    Shelly L. Pringle


    Major Advisor: Dr. Robert JC McLean

    Committee Members: Dr. Gary Aron, Department of Biology, Dr. Dittmar Hahn, Department of Biology, Dr. William Coons, Department of Biology, Victoria College

    July 11, 2014 - 2:00 pm, SUPP 257-A


    In nature, bacteria live in dynamic communities surrounded by a vast number of other bacterial species. Recent studies indicate that one mechanism by which Escherichia coli thrives within such a multitude is via production of the molecule indole. Evidence indicates that indole thwarts the quorum sensing system of acyl-homoserine lactone (AHL) producing bacteria such as Pseudomonas aeruginosa, Chromobacterium violaceum, and Pseudomonas aureofaciens. Impeding the signaling system of these bacteria ultimately leads to a lowering of toxic secretions such as pyocyanin and proteases. The aim of this research was to determine if the production of indole by E. coli increases its competitive fitness with Enterococcus faecalis. E. faecalis is a Gram positive, non-AHL producing bacteria which is found alongside E. coli as normal flora in the human intestine, as well as  in a number of mixed culture infections. E. faecalis has increasingly become a concern as it is now a leading cause of hospital-acquired infection and has developed resistance to “last-line” antibiotics such as Vancomycin. Colony counts and turbidity of ΔtnaA (the E. coli mutant incapable of degrading tryptophan and thus deficient in indole production) were measured in mixed culture with E. faecalis. Indole was then reintroduced at physiologically relevant concentrations. Contrary to previous research, in competition with E. faecalis the population size of E. coli is inhibited and indole has a further inhibitory effect.


     

    Shelly Pringle attended the University of Texas where she received a Bachelor of Arts in Biology in 2003.  Upon receiving her degree she worked as a high school science teacher, teaching Biology, Chemistry, and Integrated Physics and Chemistry. In the fall of 2012, Shelly was admitted to Texas State University–San Marcos to pursue a Master of Science in Biology.


    Thesis Defense


    Seasonal diets of the collared peccary (Pecari tajacu)

    In the Llano uplift ecological region of Texas


    Meredith Hominick

    Major Advisor: Dr. Thomas R. Simpson             

    Committee Members: Dr. M. Clay Green, Department of Biology, Dr. James F. Gallagher, Department of Biology

    July 07, 2014 –1:00 pm, SUPP 153-A


    I investigated the seasonal diets of the collared peccary (Pecari tajacu) at Mason Mountain Wildlife Management Area from June 2013 to April 2014 using microhistological analysis of fecal material.  Eighty fecal samples were collected from summer 2013 to spring 2014.   I identified and quantified 36 plant species consumed by the collared peccary. Prickly pear was consumed in all seasons with seasonal use of forbs, grasses and mast.   Annually, the bulk of the diet was comprised of browse (including prickly pear) 37.1%, forbs 32.8%, mast 22.4% and grasses 7.8%.  Primary browse species included prickly pear (Opuntia spp.) and live oak/blackjack/post oak (Quercus spp.).  Forbs, especially silver bladderpod (Lesquerella argyraea) and prickly fanpetals (Sida spinosa), were highly utilized as well.  Vegetational surveys were conducted using the Daubenmire method to sample herbaceous species and line intercept method to sample woody species.  Results of log-likelihood chi-square tests with Bonferroni corrected confidence intervals established that there were statistically significant differences between plant use and availability (P<0.001). Additionally, Manly’s alpha preference indices indicated that collared peccaries foraged selectively on silver bladderpod in spring. Prickly pear was a selected food plant in the summer. Peccaries selectively foraged on live oak/blackjack/post oak and prickly pear in the fall and selected prickly fanpetals during winter.


    Meredith received a B.S. in Biology and a minor in Environmental Science from University of the Incarnate Word in 2012. She began her studies at Texas State in the fall of 2012, and completed internships with Texas Parks and Wildlife Department as well as Bayou Land Conservancy.


    Thesis Defense

     

    Detection of Borrelia burgdorferi sensu lato Infection in Rodents
    From Disturbed and Sylvan Assemblages Across Texas


    Troy J. Maikis


    Major Advisor: Dr. Iván Castro-Arellano, Department of Biology, Texas State University

    Committee Members: Dr.Thomas R. Simpson, Department of Biology, Texas State University, Dr. Maria Esteve-Gassent, Department of Veterinary Pathobiology, Texas A&M University

    July 3, 11:00  Norris Room, Supple Science Building


    Lyme disease, caused by the bacterium Borrelia burgdorferi, affects tens of thousands of Americans each year.  Most of the research in the United States is conducted in the northeastern portion of the country.  Texas represents an under-studied area with low incidences of annual human infection.  Studying the bacterium in an area of low incidence could answer questions about why it has a greater prevalence in other parts of its range.  The present study investigated tick loads on rodents and Borrelia prevalence in disturbed and sylvan habitats at five sites in Texas across three seasons.  At four of the sites investigated, rare and relatively large bodied species that were only captured in sylvan habitats had  higher tick load than the rest of the species collected at the site.  Borrelia prevalence was found to vary seasonally, with larger numbers of infected individuals being captured in the fall.  Future studies are needed to determine if the results described herein represent a consistent pattern, but this work represents a positive step toward investigating LD in the southern portion of its range.


    Bio:  In 2006, Troy Maikis graduated with a B.S. in Ecology and Evolutionary Biology from The University of Arizona.  After receiving his degree, Troy went on to work all across the western U.S. for multiple government agencies, non-profits, and private contracting firms.  In the fall of 2012, he began his M.S. research at Texas State University.  Following the first presentation of a portion of his M.S. research, Troy was awarded the William B. Davis award by the Texas Society of Mammalogists.


    Thesis Defense


    Reliability Analysis of Rainwater Harvesting in Three Texas Cities


    Name: Dustin Lawrence

     

    Major Advisor: Dr. Vicente L. Lopes, Dept. of Biology             

     

    Committee Members: Dr. Walter Rast, Dept. of Biology, Dr. Ronald R. Hagelman, Dept. of Geography

    July 2, 2014 10:00am FAB 130


    Population growth and a prolonged drought have raised concerns about the sustainability of water resources in Texas. Recent state legislation has made financial assistance available towards the development of water supplies. The purpose of this research is to inform decision makers at state and local levels, as well as property owners about the amount of water that can be supplied by rainwater harvesting systems in Texas so that it may be included in any future planning. Reliability of a rainwater tank is a concern as people want to know to what degree a source of water can be depended on. Performance analyses were conducted on 3 cities under different climate conditions and multiple scenarios to demonstrate the importance of optimizing rainwater tank design. This was accomplished using a daily water balance model and running simulations on a range of tank sizes appropriate for rainwater harvesting at the household level. Reliability curves were produced and reflect percentage of days in a year that water can be supplied by a tank. Operational thresholds were reached in all scenarios and mark the point at which reliability increases by only 2% or less with an increase in tank size. Maximum thresholds were also reached in some scenarios and indicate a tank size that provides the maximum achievable reliability. Additional simulations considered several average years of rainfall for each city under a single scenario to determine an average ideal tank size. A payback period analysis was conducted on these tank sizes to determine the amount of time it would take to recoup the cost of installing a rainwater harvesting system.


    Bio: Dustin Lawrence was raised in New Braunfels, Texas.  After serving for 4 years in the United States Army, he received a B.S. in Geography with a minor in Biology from Texas State University in 2010. He was accepted into the Aquatic Resources program at Texas State University as a Master’s Candidate in 2011. While working towards his graduate degree, he taught 2 semesters of biology labs, interned with the Texas Commission on Environmental Quality, and started a family. He currently works full-time as a laboratory technician for New Braunfels Utilities conducting various tests to maintain water quality standards.


    Thesis Defense


    Validating environmental flow recommendations:

    drifting coarse particulate matter, invertebrates, and larval fishes


    Christopher R. Vaughn


    Major Advisor: Dr. Timothy H. Bonner, Department of Biology

    Committee Members: Dr. Floyd W. Weckerly, Department of Biology, Dr. Archis Grubh, Texas Parks & Wildlife

    July 3, 2014 – 1:00 PM, Freeman Aquatic Building (FAB) 130


    Water quantity management in Texas and elsewhere is currently managed under the theory of the Natural Flow Paradigm, which states that sound ecological riverine environments are dependent upon the dynamic character of flow.  Water quantity recommendations and standards prescribe a multi-tier flow regime, consisting of subsistence, base, and high-flow pulses, with magnitudes of each based on long-term averages of site-specific hydrographs.  The next step in water quantity management is to validate that the recommended flow regimes are sufficient to maintain a sound ecological environment, although validation methodologies are rarely incorporated into water quantity management plans.  Purposes of this study were to develop methodologies for validating flow recommendation and standards that are transferable and replicable and to quantify the value of flow tiers relating to organic drift.  Objectives of this study were to assess drift biomass of coarse particulate matter (CPM) and drift rates of invertebrates and larval fishes related to flow tiers (i.e., subsistence, base, two per season high flow pulse, one per season high flow pulse, and one per year high flow pulse) across four sites and two rivers (i.e., San Antonio and Guadalupe rivers).  A priori predictions were that CPM, invertebrates, and larval fishes were in greater biomass or densities at higher flow tiers, though at some point flows would be sufficiently high and induce a washout effect.  Findings were generally inconsistent with the predications.  Biomass of CPM did not differ among flows ranging from subsistence to two per season high flow pulse events, and densities of macroinvertebrate did not differ among flows ranging between base and one per season events.  However, densities of fluvial specialist Neoperla (Order Pelcoptera) were positively correlated with flow as a continuous variable rather than a categorical variable.  Densities of larval fishes were greatest at subsistence, base, and two per season high flow pulses and decreased at 1 per season flow pulses.  It is uncertain if a washout effect occurred or if survival of larval fishes was decreased at a higher flow pulses.  With a validation methodology in place, replications from other sites and river basins can be added to the existing model to improve statistical power and inference, along with other flow-dependent variables, in order to fully assess the value of multi-tier flow regimes.    

    Christopher Vaughn is from Arlington, Texas.  He attended Texas A&M University where he received a Bachelor of Science in Wildlife and Fisheries Sciences with an emphasis in Fisheries Ecology and Conservation in December 2011.  Immediately upon graduation, Christopher came to Texas State University to earn his Masters of Science degree in Aquatic Resources.  His primary area of research is in instream flow, water quantity management, and the effects that deviant flows have on instream biota, in particular, drifting organics.


    Thesis Defense

     

    Atmospheric Carbon Dioxide and its Relation to Carbon Cycle Perturbations during Ocean Anoxic Event 1d: A High Resolution Record from Dispersed Plant Cuticle


    Name: Jon D. Richey


    Major Advisor: Dr. Garland R. Upchurch

    Committee Members: Dr. David E. Lemke, Dept. of Biology, Dr. Noland H. Martin, Dept. of Biology, Dr. Marina B. Suarez, Dept. of Geological Sciences, University of Texas – San Antonio  

     July 3, 2014 10:00am Supple 153-A


    Past geological greenhouse intervals are associated with Ocean Anoxic Events (OAEs), which result from an increase in marine primary productivity and/or an increase in the preservation of organic matter. The end point is widespread black shale deposition combined with a long-term atmospheric positive δ13C excursion from an increase in the burial of 12C. Some OAEs show a negative δ13C excursion preceding the positive excursion, indicating a perturbation in the global carbon cycle prior to the initiation of these events.

    The Rose Creek Pit (RCP) locality, southeastern Nebraska, is currently the only known terrestrial section that preserves OAE1d (Cretaceous, Albian-Cenomanian Boundary) and has abundant plant organics. These features allow for a combined analysis of carbon isotopes and stomatal index (SI) to determine changes in the cycling between carbon pools and their relation to inferred paleo-CO2. To do this, RCP SI data were calculated from the cuticle of Pandemophyllum kvacekii (an extinct laurel) and related taxa, and fitted to δ13C curves derived from fossil gymnosperm charcoal and lignitized wood, as well as other published δ13C profiles from RCP and nearby sediment cores. Absolute values of CO2 were estimated using three published transfer functions based on species of extant Lauraceae.

    SI indicates changes in CO2 coincident with changes in δ13C.  Near the bottom of RCP, pCO2 was relatively low (330−615ppm). At the same level, this study records a negative δ13C shift of ~2.8−2.96‰ compared to pre-excursion samples collected near RCP, similar to that of other RCP δ13C curves (~2.14−2.4‰). All RCP δ13C curves show that the negative excursion lasts through ~3.3m of the section. During this negative excursion, pCO2 increases from the pre-excursion values to a high of ~380−800ppm. After the negative excursion, all RCP δ13C curves and pCO2 values show a slow return to pre-excursion values. Despite the finer sampling intervals of this study compared to other RCP δ13C curves, δ13C curves from fossil gymnosperm charcoal and lignitized wood do not record the positive excursion recorded in carbonate δ13C curves during OAE1d. This study confirms that δ13C of fossil wood, whether coalified or charcoalified, and SI from dispersed cuticle can reliably capture carbon cycle perturbations and changes in atmospheric CO2 around OAEs.


    Bio: Jon D. Richey was raised in Tyler, TX. After a long break from higher education, he received a B.S. in Biology from Texas State University – San Marcos in 2011, and entered into the Master’s program in Biology that same year. Jon received a National Science Foundation Graduate Research Fellowship in 2013 and a Texas State Thesis Support Fellowship in 2014. He will enter the Ph.D. program in Earth and Planetary Sciences at the University of California – Davis Fall 2014.


    Thesis Defense


    Variation in rumen-reticulum fill in white-tailed deer (Odocoileus virginianus)


    Meredith R. E. Aiken

     

    Major Advisor: Floyd W. Weckerly            

    Committee Members:Dr. Thomas R. Simpson, Department of Biology, Dr. M. Clay Green, Department of Biology

    June 24, 2014 – 11:00 AM, Supple 153


    Understanding variation in rumen-reticulum fill allows us to predict how ruminants will accommodate fluctuations in food supplies and animal production demands. Studies suggest rumen-reticulum fill increases with lower quality diets (low crude protein-CP, high acid detergent fiber-ADF) and browse diets compared to pelleted diets. Rumen-reticulum fill presumably fluctuates with the demands of antler growth and access to females during the mating season, in male white-tailed deer, and during late gestation and lactation in females. Previous research has mainly examined the relationship between rumen-reticulum fill and body mass; however, multiple factor may be influencing rumen-reticulum fill. Herein, I examined the influences of nutrition (ADF and CP), diet type (pelleted or browse), reproductive demands (males in rut vs. males outside of rut, lactating vs. non-lactating) as well as body mass, rump fat, age, and sex on wet and dry rumen-reticulum fill. I collected white-tailed deer (122 males, 152 females) from Kerr Wildlife Management Area, Texas (pen-raised, free ranging) and a private ranch in south Texas. I built models and used Akaike Information Criteria to select competing models to understand which hypotheses explained rumen-reticulum fill dynamics. The only prediction that was not falsified was that lactating females had greater fill. In regards to nutrition, wet fill decreased, as ADF increased. This is likely because of chemostatic factors that regulate food intake and diet quality when dietary fiber is ‘low’. Deer consuming a pelleted diet had greater wet and dry rumen-reticulum fill than deer consuming a browse diet. My findings indicate that scaling relationships between body mass and rumen-reticulum fill were allometric. Additionally, rumen-reticulum fill is influenced by a wide variety of factors.


    Meredith received a B.S. in Wildlife and Fisheries Science from Texas A&M University in 2009. She began her studies at Texas State in the fall of 2012, and was recently awarded the Leadership Scholarship from the Max McGraw Wildlife Foundation and Wildlife Management Institute.

     


    Thesis Defense


    Current velocity and flow mediated diets of larval fishes


    David S. Ruppel


    Major Advisor: Dr. Timothy H. Bonner

    Committee Members: Dr. Floyd W. Weckerly, Department of Biology, Dr. Alan W. Groeger, Department of Biology

    June 12, 2014 – 12:30 PM, FAB 130


    Purposes of this study were to test two theories relating to food consumption of larval stream fishes.  Flow-pulse feeding theory states that larval fish food consumption will be greater following nutrient-rich flow pulses.  Drift-feeding theory states that larval fishes enter the drift at night to consume food items under the protection of darkness.   Objectives of this study were to quantify gut fullness and occurrence and abundances of food items consumed among larval fishes taken during subsistence flow, base flow, and several high flow pulse tiers (e.g., one per season, one per year) and between larval fishes taken during the day in slackwater habitats and larval fishes taken during the night in swift water habitats.  During one year period of observation among four sites and two rivers, mesolarval of obligate riverine taxa (i.e., Cyprinidae, Catostomidae, Percidae) had greater gut fullness within 28 d following a 1 per season flow event than those taken within 28 d following subsistence flow, base flow, 2 per season flow event.  Greater gut fullness during a 1 per season flow event was attributed to greater numbers of copepods and organic detritus consumed.  However, gut fullness and occurrences and abundances of food items consumed by metalarvae were independent of flow.  Among mesolarvae and metalarvae collectively and among taxa, gut fullness was greater during the day for fishes taken in slackwater habitat than those taken at night from swift water habitats.  Larval fishes within lowland rivers of western gulf slope drainages of Texas conformed only partially to larval fish feeding theories.  Drift-feeding theory likely is not a mechanism to explain larval drift at night, and the value of flow pulses to larval fish feeding and subsequent recruitment was not consistent among larval life stages.   Nevertheless, this study documents for the first time larval fish food consumption in lowland rivers and establishes a process to quantify the value of flow tiers relevant to the stream fish community.


    David received a B.S. in Zoology from Northern Michigan University in May 2012. David began his studies at Texas State University in Summer 2012 and was recently awarded the Certificate of Excellence in Spring 2014.  David currently serves as President of the Aquatic Biology Society and is a member of the Texas Chapter of the American Fisheries Society. 


  • Thesis Defense
     

    INVASIVE HETEROPHYID TREMATODES AND THEIR NATIVE AQUATIC HOSTS IN TEXAS


    Daniel C. Huston

    Major Advisor:
    Dr. David G. Huffman

    Committee Members:
    Dr. Ivan Castro-Arellano, Department
    Dr. Kenneth G. Ostrand, U.S. Fish and Wildlife Service

    May 8, 2014 – 1:00 PM, Supple 116


    Centrocestus formosanus and Haplorchis pumilio are invasive Heterophyid trematodes which have been introduced to Texas via introductions of their first intermediate snail hosts. Second intermediate hosts for both of these trematodes include multiple species of freshwater fishes, which become infected when exposed to free-swimming trematode cercariae. Centrocestus formosanus cercariae encyst in the gills of their fish hosts, whereas H. pumilio cercariae penetrate the epidermis and encyst in the head and tissues of the fin insertions. Though mortalities in fish hosts have been attributed to these trematodes in artificially confined systems such as fish culture, there are no reported fish kills attributed to these trematodes in the wild. We speculate that many fish species restricted to stable spring-fed systems would experience increasing parasite burdens of these trematodes over time. High metacercarial intensities in the gills could lead to reduced respiratory efficiency, while high metacercarial intensities in the fin insertions could reduce swimming performance. In order to test this hypothesis and estimate the impact of these parasites, we developed a methodology for the artificial infection and swimming endurance testing of small fish hosting various intensities of trematode metacercariae. We found we were able to induce a wide range of metacercarial intensities in our fish using wild caught Melanoides tuberculata infected with either C. formosanus or H. pumilio, and that we could test the swimming endurance of these fish with a specially constructed swim tunnel. This methodology has laid the groundwork for the development of a mathematical model of the impact of these parasites at various metacercarial intensities. In addition, we utilized artificial infection methods to examine host specificity for C. formosanus. Though C. formosanus has previously been reported to infect frogs and toads in Asia, the potential for Texas amphibians to become infected has been ignored. We exposed adult San Marcos salamanders (Eurycea nana) and larval leopard frogs (Lithobates berlandieri) to the cercariae of C. formosanus. We found that while the neotenic E. nana was refractory to infection, L. berlandieri tadpoles were susceptible. We believe that the active respiratory rhythm of the tadpoles when compared to the passive respiratory system of the salamander may account for this observation. Lastly, we examined host breadth and built a preliminary second intermediate host list for H. pumilio in Texas. Haplorchis pumilio has been known to occur in Texas for over a decade, and has been reported infecting snails in multiple spring-fed systems throughout the state. However, no second intermediate fish hosts have been reported hosting H. pumilio metacercariae in Texas, or the U.S.A. We examined the federally listed fountain darter (Etheostoma fonticola), Devils River minnow (Dionda diaboli), Pecos gambusia (Gambusia nobilis), Comanche Springs pupfish (Cyprinodon elegans); Texas protected Rio Grande darter (Etheostoma grahami) as well as the largemouth bass (Micropterus salmoides). With the exception of C. elegans, all species examined were positive for H. pumilio. We conclude that H. pumilio is likely present in many systems where their snail hosts have become established, and these finding present concern for human and wildlife health. 



    Daniel Huston was born in Corpus Christi, TX. Daniel Received a B.S. in wildlife biology from Texas State University in 2011, and began an M.S. in biology in 2012. He has worked for the U.S. Fish and Wildlife Service throughout his graduate career, and enjoys topics pertaining to invertebrate biology.
     

    Dissertation Defense
     

    Wetlands, birds, and changing landscapes: examining avian communities
    at multiple spatial extents


    Suzanne Whitney



    Major Advisor:
    Dr. Joseph Veech

    Committee Members:
    Dr. Floyd Weckerly, Department of Biology
    Dr. Weston Knowlin, Department of Biology
    Dr. Erica Fleishman, University of California - Davis
    Dr. Curt Flather, USDA – Forest Service, Fort Collins, CO


    May 9, 2014 – 9:00 AM, SUPPLE 116



    Destruction and impairment of wetlands has been extensive throughout the conterminous United States, resulting in the loss of both crucial ecosystem functions and productive habitat for a wide variety of organisms. Over the last few decades, efforts to protect, restore, and create wetlands have led to increases in wetland area and improvements to wetland quality in many locations. However, wetlands are difficult to create or restore, and whether these initiatives will lead to wetland function that approaches historical levels remains unclear. My research focuses on how the diverse bird communities that rely on wetlands might be affected by changes to their primary habitat and the surrounding landscape. I utilized data from the North American Breeding Bird Survey (BBS) and the National Land Cover Database (NLCD) to develop a set of spatially-explicit abundance models for each of 24 species of wetland-breeding birds. Independent variables in these models included combinations of three different aquatic habitats as well as other land cover types that could potentially influence species abundance. I compared the models in an information-theoretic framework to determine which cover types most influenced species abundance. All species were positively associated with one or more types of aquatic cover, and when considered in the broad spatial context of entire landscapes, other cover types likely affect abundances of many species as well. I also used data from the BBS and the NLCD to develop an inventory describing the characteristics of wetland bird communities and the composition of the landscape (including how these factors have changed over time) within several Bird Conservation Regions. The data included in this inventory indicate that wetlands and the bird communities associated with these systems have continued to experience substantial regional changes in recent years. Further, a review of previously published studies on avian use of anthropogenic wetlands suggests that while created and restored wetlands do support substantial bird communities, these assemblages are typically dissimilar from those at natural wetlands.



    Suzanne graduated from California Lutheran University with a B.S. in Biology in 2004 and received her M.S. in Environmental Studies from the College of Charleston in 2008. She taught environmental education and worked on various ecological research projects in Oregon, California, Massachusetts, Puerto Rico, Mississippi, and South Carolina before moving to Texas. Suzanne entered the Aquatic Resources Ph.D. program at Texas State University in the fall of 2009 and has been supported as an Instructional Assistant for Organismal Biology and as a National Science Foundation GK-12 fellow with Project Flowing Waters.
     


     



     

    Dissertation proposal Defense

    Role of IBR5 in modulating SCF ubiquitin ligase mediated protein degradation in plant hormone response


     

    Thilanka Jayaweera

     

    Major Advisor:
    Dr. Nihal Dharmasiri, Department of Biology, Texas State University.


    Committee Members:
    Dr. HongGu Kang, Department of Biology, Texas State University
    Dr. Sunethra Dharmasiri, Department of Biology, Texas State University
    Dr. Alan Lloyd, MCDB, University of Texas at Austin
    Dr. William Gray, Department of Biology, University of Minnesota

     

    May 9, 2014 – 2:00 pm Supple 153



    The SCF (Skp1, Cullin, F-box) ubiquitin ligase dependent protein degradation is a common mechanism that regulates protein abundance of both plants and animals. This mechanism is involved in many cellular processes such as cell cycle, signaling cascades, and developmental processes. Several plant hormone signaling pathways such as auxin, gibberellic acid, ethylene, and jasmonic acid use the SCF dependent ubiquitin-proteasome pathway to regulate gene expression. In auxin signaling, auxin promotes the interaction between Aux/IAAs and SCFTIR1/AFBs and thereby enhances the ubiquitination and degradation of Aux/IAA repressors through 26S proteasome. The degradation of Aux/IAAs relieves the repression on ARFs leading to the modulation of gene transcription. Dual specificity phosphatase, IBR5 was identified as a protein involved in auxin signaling. Unlike in many other auxin insensitive mutants, Aux/IAA proteins are not stabilized, but rather degrade faster in ibr5-1 compared to the wild type suggesting that IBR5 negatively regulates Aux/IAA degradation. Also, the loss of ABP1 auxin receptor function leads to rapid Aux/IAA degradation similar to ibr5-1, suggesting that ABP1 and IBR5 function in a common signaling pathway to regulate SCFTIR1/AFBs dependent Aux/IAA degradation.

    Overall goal of this study is to understand the molecular mechanism by which IBR5 regulates SCF ubiquitin ligase mediated protein degradation. Three ibr5 mutant alleles, ibr5-1, ibr5-4 and ibr5-5 as well as alternatively spliced IBR5.1 and IBR5.3 will be used to further understand the function of IBR5 in the above process. Also, experiments will be carried out to understand the interaction between ABP1 and IBR5, hypothesizing that IBR5 links ABP1 and TIR1/AFBs dependent auxin signaling pathways.



    Thilanka Jayaweera was raised in Kandy, Sri Lanka and received his BS degree in Molecular Biology and Biotechnology from University of Peradeniya, Sri Lanka in May 2009. Then he entered the graduate College of Texas State University and earned his MS degree in Biology in fall, 2011. Thilanka entered the aquatic biology PhD program in spring 2012 to continue his research focused on auxin signaling in plants development. During his stay at Texas State he won several awards including Biology colloquium award, Colene Drace Cell Biology award, Graduate college scholarship and Dorothy Coker Research Fellowship.

    Thesis Defense


    Factors Affecting Phosphorus Uptake in Karstic Rivers of the Edwards Plateau, Central Texas


    Aaron P. Swink
     
     
    Major Advisor:   
    Dr. Weston Nowlin
     
    Committee Members:
    Dr. Benjamin Schwartz, Department of Biology
    Dr. Alan Groeger, Department of Biology
     
     
    April 23, 2013 – 1:00 PM, FAB 130


    Phosphorus (P) is a limiting nutrient for microbial primary producers in many aquatic systems and thus an overabundance of it via urban and agricultural runoff has led to eutrophication of waterways across the globe. There are a variety of ways to study nutrient dynamics, but nutrient spiraling theory is often used as a measure of efficiency and limitation in lotic ecosystems. However, the consistency, accuracy, and utility of the traditional metrics are questionable, especially as the discharge and hydrologic complexity of a stream or river increases. Thus, there is a relative dearth of knowledge on nutrient uptake in larger rivers, especially in spring-fed rivers. Recent improvements in methodology (i.e., pulsed tracer addition experiments) have allowed nutrient uptake length measurements to be performed in larger rivers in which it was cost-prohibitive to perform more traditional uptake methods (i.e., short-term steady state injection or isotope additions).
    The purpose of this study was to quantify P uptake and examine the factors that influence P uptake in relatively larger discharge riverine ecosystems, specifically, in karstic, spring-fed rivers of the Edwards Plateau, in central Texas.

    We utilized a pulsed tracer addition method to measure P uptake in 7 rivers and coupled these estimates with measurements of a diversity of in-stream and reach-level variables which are likely to exhibit influences on P uptake and retention in lotic ecosystems
    We found that levels of chlorophyll-a and particulate P in benthic biofilms were significant predictors of uptake rates. In general, there was a high degree of covariance between benthic chlorophyll-a, benthic particulate P, water column SRP and dissolved mineral load indicating that biological and physicochemical factors are highly interrelated and work in concert to affect P cycling in these systems. Our results indicate that P uptake rates for the rivers in this study are rapid when compared to similarly sized non-karst rivers due to (1) the low availability of dissolved phosphate in the river, (2) abundance of algae-dominated biofilms, and (3) interaction with dissolved minerals (especially Ca2+), presumably resulting in precipitation of insoluble mineral forms of P. We have also shown that pulsed tracer additions can be a simple and effective tool for studying nutrient dynamics in streams and rivers.


    Aaron Swink is from Kapaa, Hawaii. He attended Texas A&M University where he received a Bachelor of Science in Bioenvironmental Science in 2009. He has since worked for invasive species eradication projects in Hawaii and has done water quality monitoring for the San Marcos Observing System (SMOS) and the San Marcos Habitat Conservation Plan (SMHCP). In 2012, he was admitted to Texas State University to pursue a Master of Science in Aquatic resources. His primary areas of research interest are in freshwater biogeochemistry and karst hydrogeology and geomorphology.

    Thesis Defense
     

    Mating behavior and the effects of turbidity on association preferences in the fountain darter, Etheostoma fonticola.


    Sophia L. DeColo

     

    Major Advisor:
    Dr. Caitlin R. Gabor

    Committee Members:
    Dr. Andrea Aspbury, Department of Biology
    Dr. Kenneth Ostrand, USFWS


    April 10, 2014 – 10:00 AM, Supple Norris Room



    Anthropogenic activities such as industrial pollution, aquatic recreation, and increased groundwater withdrawal pose serious threats to aquatic ecosystems. Rising levels of turbidity as a result of these threats have serious consequences for aquatic organisms as turbidity degrades visual communication. The federally endangered fountain darter, Etheostoma fonticola, is endemic to the clear spring-fed headwaters of the San Marcos and Comal Rivers in central Texas. Here we tested the impact of simulated turbidity on association preferences in E. fonticola. We examined whether male and female E. fonticola exhibit preferences for larger over smaller individuals across two vision levels; clear and impaired (simulated low turbidity). We found that both female and male E. fonticola do not exhibit association preferences for larger over smaller individuals of the opposite sex or the same sex. Simulated low turbidity levels affected the total amount of time both female and male E. fonticola spent associating with individuals of the opposite sex. Reducing the amount of time spent associating with the opposite sex may reflect a reduction in the amount of time spent evaluating potential mates, thereby weakening sexual selection for traits important in mate choice. These results indicate that compromised vision hampers association preferences in E. fonticola, which may be of concern for the conservation and management of this endangered species.


    Additionally we investigated the mating behavior of E. fonticola. Association preferences in E. fonticola did not reveal female or male mate preferences for size in this species. However, male-male interactions may influence mating behavior in E. fonticola and larger and smaller males may experience variation in mating success regardless of female preferences for size. Here we examined whether larger and smaller male E. fonticola exhibit differences in agonistic behavior and mating success. We found that larger males exhibited higher rates of aggressive behaviors and smaller males in turn exhibited more defensive behaviors. However, differences between larger and smaller males in male-male interactions were not correlated with differences in spawning success. These results suggest that male size influences dominance relationships in E. fonticola but not mating success. Combined with the results from our previous study, body size is not an important male trait for evaluating or choosing potential mates in female E. fonticola. As changing environmental conditions and anthropogenic activities threaten this endangered species, further understanding of the mating behavior of E. fonticola may be critical for their conservation and persistence.



    Sophia DeColo was born in Boston, Massachusetts. She attended Northeastern University where she received a B.S. in Biology in 2010. While at Northeastern, she conducted undergraduate research in vertebrate paleontology and had the opportunity to work in the penguin colony at the New England Aquarium. Since then she has pursued various outlets to engage in animal husbandry and aid in conservation efforts. In 2012, Sophia entered Texas State University to pursue a Master of Science in Population and Conservation Biology.

    Thesis Defense


    Influence of a population irruption by Roosevelt elk on a vegetation index


    Heath D. Starns

     

    Major Advisor:
    Dr. Floyd W. Weckerly

    Committee Members:
    Dr. M. Clay Green, Department of Biology
    Dr. Thomas R. Simpson, Department of Biology

     

    April 4, 2014 – 11:00 AM, SUPP 257



    Understanding the factors that influence population growth is central to the study of any species. Large herbivores can influence their food supplies through herbivory. Over 23 years just before and throughout an irruption by a Roosevelt elk population I assessed temporal and spatial patterns of the Normalized Difference Vegetation Index (NDVI). My objectives were to determine if elk herbivory was associated with NDVI and whether the plant community foraged by the irruptive population was tolerant or resistant to elk grazing. Using Landsat 5 Thematic Mapper imagery, I obtained estimates of NDVI for three areas of Redwood National and State Parks, each inhabited by distinct populations of Roosevelt elk. Each population exhibited a different pattern of growth through the time series of the study. One population underwent the irruptive growth pattern while the other two populations did not. Using piece wise regression, I detected temporal changes in NDVI for the area used by the irruptive population that suggested a decline in forage biomass during the end of the dry season but I detected no decline in NDVI at the peak of the growing season. My findings suggest that the area used by the irruptive elk population may have undergone changes in plant community composition favoring plants that were resistant to elk grazing.



    Heath received a B.S. in Wildlife Ecology and Management from Texas A&M University in August 2008. After graduating, he worked as assistant manager on a wildlife-focused ranch in south Texas for three years. Heath began his studies at Texas State in the Fall of 2012, and was recently awarded the Thesis Research Support Fellowship in Spring of 2014.

    Thesis Defense
     

    OCULAR HISTOLOGY IN THREE SOUTH CENTRAL TEXAS PAEDOMORPHIC SALAMANDER SPECIES (EURYCEA SOSORUM, EURYCEA NANA AND EURYCEA RATHBUNI) AND COMPARATIVE OCULAR DEVELOPMENT OF TWO MORPHOTYPES


    Ruben U. Tovar


    Major Advisor:
    Dr. Dana García

    Committee Members:
    Dr. Caitlin Gabor, Department of Biology, Texas State University
    Dr. Glenn Longley, Department of Biology, Texas State University


    April 2, 2014 – 10 am, Supple 153



    The recent focus on conserved genes expressed through development has allowed for great headway in understanding the molecular mechanisms responsible for the variation seen among organisms. Understanding the expression of these integral developmental genes has implications with respect to evolutionary processes. The south central Texas Eurycea clade presents a unique continuum of karst phenotypes, having representative species of both subterranean and above ground morphotypes. By describing the adult ocular morphology and the developmental pathways leading to it, I hope to lay the foundation for better understanding the underlying molecular mechanisms responsible for subterranean phenotypes in a karst salamander system.
    I am interested in exploring the evolution of developmental mechanisms that has resulted in the divergent ocular morphologies seen between the subterranean Texas blind salamander (Eurycea rathbuni) and the above ground Barton Springs salamander (Eurycea sosorum). To better understand the developmental processes of ocular reduction, a description of adult ocular histology was done first. The adult histology revealed an underdeveloped eye in the subterranean species E. rathbuni and well-developed eyes in the above ground species E. nana and E. sosorum. To understand how differences in gene expression influence the divergent outcomes of eye development between the two morphotypes, expression of genes involved in ocular development (pax6 and shh) was examined in E. rathbuni embryos and E. sosorum embryos. Pax6 and Shh are conserved across all animals and share similar expression patterns through development in species in which their expression has been examined. I found that both E. rathbuni and E. sosorum express Pax6 and Shh,butthe time course and location of Pax6 and Shh expression in the developing eye of the blind salamander differed from that in the sighted salamander. Furthermore, I observed unexpectedly that the lens, which functions in inducing development of the retina in other organisms, persists in the Texas blind salamander into the latest embryonic stages. I conclude that these salamanders present an ideal system in which to study the evolutionary and developmental mechanisms that lead to the variation in morphotypes seen in the Eurycea clade.



    Ruben Tovar was born in San Antonio, Texas. He received a B.S. in Interdisciplinary Studies with a minor in Biology from the University of Texas, Arlington in 2010. His research interests lie broadly in herpetology, but his question of interest is in the subdiscipline of evolutionary developmental biology.

    Dissertation Proposal
     

    Predicting Future Range Expansion of Whooping Crane (Grus americana) Winter Habitat Using Long-Term Census and Remotely Sensed Data


    Nicole A. Davis

     

    Major Advisor:
    Dr. Thomas Hardy, Department of Biology, Texas State University

    Committee Members:
    Dr. Clay Green, Department of Biology, Texas State University
    Dr. Susan Schwinning, Department of Biology, Texas State University
    Dr. Jennifer Jensen, Department of Geography, Texas State University
    Dr. Elizabeth Smith, International Crane Foundation


    April 1, 2014 – 3:30 pm Supple 112



    Individual-based models (IBMs) have been utilized to explain various ecological processes. Examples include the influence of winter range carrying capacity on migrating bird survival, habitat choice in relation to range distribution, and changes in population dynamics from habitat degradation. The aim of my dissertation is to develop a spatially-explicit individual-based model to examine how behavioral patterns in wintering whooping cranes (Grus americana) influence territorial expansion and, most importantly, if these patterns may potentially limit territorial expansion below the seemingly available habitat. Whooping cranes have remained an endangered species since 1967, with only one wild-population remaining; the Aransas-Woods Buffalo population. Current conservation strategies regarding land protection for the Aransas-Woods Buffalo population within their wintering grounds along the Texas coast are limited by the uncertainty of future distribution as the population increases. I will develop winter range habitat suitability models for subadult and adult whooping cranes for inclusion in the individual-based model. The overall goal of the final IBM is to mimic past distributions of the Aransas-Woods Buffalo population within their wintering grounds along the Texas coast. The IBM could then be used as a conservation strategy tool to aid in future protection of the endangered Aransas-Woods Buffalo whooping crane population by producing predictions of winter distribution as the population increases.



    Nicole received a B.S. in Biology from the University of Texas at San Antonio in December 2007 and a M.S. in Biology from Texas A&M University-Corpus Christi in May 2011. While attending Texas A&M-Corpus Christi, she was a NOAA Environmental Cooperative Science Center fellow and received the Teresa Heinz Scholar for Environmental Research Scholarship. Nicole joined the Aquatic Resources PhD program at Texas State University-San Marcos in the spring of 2012. She has remained an intern with the International Crane Foundation since joining Texas State and recently received a research grant from the Coypu Foundation.

  • Dissertation Proposal Presentation

    Influence of Brain-Derived Neurotrophic Factor and Family History of Alcohol Dependence on Alcohol Consumption Characteristics of Healthy Social Drinkers


    Shobhit Sharma

    Major Advisor:
    Dr. Natalie Ceballos, Department of Psychology, Texas State University

    Committee Members:
    Dr. Brett Ginsburg, Department of Psychiatry, UTHSCSA
    Dr. Dana Garcia, Department of Biology, Texas State University
    Dr. Michelle Lane, Department of FCS, Texas State University
    Dr. Shannon Weigum, Department of Biology, Texas State University


    October 30, 2013 – 1:00 pm, LBJSC 3-11.1



    Studies in animal models have suggested that decreased brain-derived neurotrophic factor (BDNF) levels may also be related to a genetic propensity for problem drinking. Studies in human participants have confirmed this relationship by examining presence vs. absence of the Val66Met single-nucleotide polymorphism (rs6265 SNP) of the BDNF gene, a genotype associated with decreased activity-dependent release of BDNF. Research suggests that BDNF may play a significant role in the reinforcing and rewarding effects of alcohol consumption and may be linked to genetic vulnerability to alcohol dependence. The proposed study will have following specific aims. Aim 1: will examine potential differences in salivary BDNF profiles among healthy social drinkers (aged 18-27) with and without a family history of alcohol dependence (FH), and the relationship of BDNF levels to alcohol use characteristics in these groups. Hypothesis 1: BDNF profiles are expected to be related to alcohol use characteristics such as quantity/frequency of alcohol consumption (the Val66Met polymorphism and lower BDNF associated with higher drinking levels), age of first drink and age of first drunken episode (lower BDNF associated with earlier initiation of alcohol use and drinking to excess), and binge drinking habits (lower BDNF associated with higher frequency and greater severity of binge drinking) compared negative controls (e.g., Val66Val). Aim 2: will examine the relationship between BDNF polymorphisms and 16-hour cortisol levels. Hypothesis 2: Previous studies have shown that carriers of the met-allele exhibit significantly attenuated HPA-axis activity. Similarly, individuals who are family history positive for alcohol dependence have also been shown to have attenuated HPA responses to stress. Preliminary data suggest a trend toward alcohol use differences between BDNF groups. The second step in the project, 16-hour cortisol levels, is currently underway in the existing genotyped participants. Based on this research, it is proposed that a synergistic effect of BDNF genotype and family history status may occur, such that family history positive participants with the BDNF Val66Met variant will show a differential effect on diurnal variation of cortisol levels as compared to all other groups.



    Shobhit earned an MS in Biology from Texas State University in 2011 and entered the Ph.D. programin the Department of Biology at Texas State University in fall 2011. As a Ph.D. student, he has been employed as an instructional assistant for Anatomy and Physiology labs. In April 2013, Shobhit was awarded John P. McGovern Fellowship for his research from the Texas Research Society on Alcoholism in 2012. He also presented his research work at the Experimental Biology 2013 meeting.

    Dissertation Defense
     

    THE TROPHIC ECOLOGY OF PHREATIC KARST AQUIFERS


    Benjamin T. Hutchins



    Major Advisor:
    Dr. Benjamin Schwartz

    Committee Members: 
    Dr. Timothy Bonner, Department of Biology, Texas State University-San Marcos
    Dr. Weston Nowlin, Department of Biology, Texas State University-San Marcos
    Dr. Annette Engel, Department of Earth & Planetary Sciences, University of Tennessee-Knoxville
    Dr. Stephen MacAvoy, Department of Biology, American University


    Nov. 1, 2013 – 1:00 PM, Supple 116



    Food web complexity is closely tied to nutrient availability which is often assumed to be severely limiting in subterranean ecosystems. However, this is assumption is largely based on studies in relatively shallow habitats dependent on allochthonous, photosynthetic detritus. The Edwards Aquifer of Central Texas provides an interesting opportunity to examine food web structure in a deep, phreatic setting because 1) it has an unusually diverse faunal assemblage and 2) both allochthonous detritus and autochthonous, chemolithoautotrophic organic matter are supplied to the aquifer in spatially isolated regions. Both of these nutrient sources are spatially and temporally variable within the aquifer, and both are consumed by metazoan taxa. However, the relative contribution of allochthonous and autochonous organic matter to consumers varies within the aquifer as a function of hydrologic proximity to organic matter sources. The presence of two disparate food resources promotes niche partitioning among sympatric species, and this trophic specialization is reflected in morphologic adaptations. Horizontal trophic diversity (primary consumers feeding on multiple resources) increases biomass available to higher level consumers, resulting in a food web longer than any previously reported from a groundwater habitat. A meta-analysis of groundwater foodweb studies suggests that ecosystem age, ecosystem size, and predator-prey mass ratios also affect trophic length in groundwater foodwebs. These data suggest that the prevailing paradigm of food web structure in subterranean ecosystems is overly simplistic.



    Benjamin Hutchins was born in Louisville, KY and received a B.S. in Biology from Western Kentucky University in 2005. He then attended American University in Washington DC, earning a M.S. in Biology in 2007. Ben has acted as a biological consultant on several projects, and he and his wife Carrie served 2 years as Peace Corp volunteers in Morocco prior to his entry into the Aquatic Resources Ph.D. program in the fall of 2009.

    Thesis Defense
     

    Prevalence of Batrachochytrium dendrobatidis in amphibian communities of Central Texas and Tamaulipas, Mexico


    Andrea Villamizar Gomez

     

    Major Advisor:
    Dr. Michael Forstner

    Committee Members:
    Dr. Dittmar Hahn, Dept. Biology
    Dr. Ivan Castro Arellano, Dept. Biology


    November 05, 2013 – 8:00 am Norris Room, Supple 376-A.



    Batrachochytrium dendrobatidis (Bd), a fungus that causes chytridiomycosis on infected amphibians, and has been implicated as a potential causative agent in the amphibian population declines of the past 50 years. This study seeks to assess the prevalence of Bd in amphibian communities in Central Texas and the state of Tamaulipas, Mexico. In Central Texas two counties were evaluated during the spring of 2012, and for the Tamaulipas assessment samples of 18 amphibian species were collected between 2004 and 2008 at 16 different localities that ranged from 100-2900 meters in elevation. All the samples were obtained from non-consumptive toe clippings and swabs. The presence of the pathogen was assessed by using a Taqman quantitative real time PCR (qPCR) assay in a highly sensitive approach to detection. Interestingly, there is a low prevalence for Bd in Central Texas in comparison with previous studies conducted in this area. All samples tested from Tamaulipas were negative for the presence of the pathogen. This study implies that monitoring the pathogen in both southern Texas and northern Mexico requires explicit changes to normal surveys protocols. To better understand the dynamics of the fungus in these environments, will require increased efforts during periods that accommodate pathogen thermal preferences. Further exploration in this regions and adjacent areas will help to inform of the prevalence, widespread and epidemiology of Bd and would help prioritize conservation efforts.



    Andrea Villamizar Gomez, was born in Bogota, Colombia. She completed the degree of Bachelor in Veterinary Medicine at UDCA University in Bogota. After graduating with a Bachelor’s degree in 2008, she practiced for 3 years before starting her Master’s program in Wildlife Ecology at Texas State University-San Marcos under the supervision of Dr. Michael Forstner during August 2011.

  • Spring 2018