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Noland Martin, Ph.D.

Dr. Martin taking a photo in front of an iced over lake, with mountains in the background.

Noland Martin, Ph.D.

Associate Professor
nm14@txstate.edu
512.245.3317
Curriculum Vitae (PDF)

Ph.D., 2004, Duke University
M.S., 2000, University of Oregon
B.S., 1996, University of Texas

Courses

Genetics (BIO 2450)
Evolution (BIO 4301)

Research Interests

The primary focus in the lab centers around the ecological genetics of speciation and natural hybridization. How are populations transformed into new species? What are the evolutionary consequences of natural hybridization? These are two of the most fundamental and interrelated questions in evolutionary biology, and with new ecological, molecular and statistical genomic techniques, answering them is a distinct possibility. The evolution of new species is generally thought to be a consequence of genetic divergence between populations ultimately resulting in complete reproductive isolation. However, reproductive isolation is often incomplete and hybridization may occur between genetically divergent taxa. While the mere existence of hybrids often fuels debate as to the usefulness of long-standing species concepts, naturally hybridizing taxa provide unique opportunities to study speciation "as it happens" before the process has been completed. To understand hybridization and speciation in both a genetic and ecological context, I use large-scale field studies, greenhouse experiments, and genomic-scale analyses in a variety of plant and animal study systems. Evolutionary biology requires the integration of diverse types of data, and my research program illustrates the potential for using these data to ask a broad range of questions about the origin of species and the long-term consequences of natural hybridization.

One of the study system that we work on is Louisiana Iris. The Louisiana Iris species complex consists of three geographically widespread species: Iris brevicaulis, Iris, fulva, and Iris hexagona. All species are found sympatrically in southern Louisiana where natural hybrid zones can frequently be encountered. We are interested in the consequences of such natural hybridization, which can include adaptive introgression and even hybrid speciation. We have utilized QTL mapping to examine the genetic architecture of reproductive isolating barriers between Louisiana Iris species, which has also resulted in the identification of genomic regions responsible for adaptive introgression. We are also using high-throughput “next-generation” sequencing technologies to quantify introgression patterns and perform admixture mapping in natural hybrid zones.

We are actively examining natural hybridization in another plant system, Mahonia, as well. Mahonia trifoliolata (a.k.a Agarita) is a widespread shrub that thrives throughout much of the arid southwestern North America. A congener, Mahonia swaseyi is endemic to the Balcones Escarpment of Central Texas where both species exist in sympatry. Where the species co-occur locally, hybrids form, and the lab has initiated new projects examining the ecological and evolutionary dynamics of local hybridization in these two taxa.

Natural hybridization can not only evolutionary consequences but conservation implications as well. We are actively working with a variety of state and local agencies to assess the conservation status of a number of taxa by performing population genetic and ecological work in fish (Macrhybopsis), and mussel populations as well. For instance, we have found evidence of natural hybridization in Macrhybopsis to be associated with ecological gradients and have published on the potential conservation implications of such natural hybridization.

Selected Publications

Zalmat, A.S., V.A. Sotola, C.C. Nice, and N.H. Martin. 2021. Genomic population structure in the Louisiana Iris complex reveals patterns of current and historical introgression. Accepted minor revisions American Journal of Botany.  

Sotola, V.A., K. Sullivan, B. Littrell, N.H. Martin, D.S. Stich, and T.H. Bonner. 2021. Short-term responses of freshwater mussels to floods in a southwestern U.S.A. river estimated using mark–recapture sampling. Freshwater Biology 66: 349-361. DOI: 10.1111/fwb.13642  

Sotola, V.A., D.L. Ruppel, T.H. Bonner, C.C. Nice, and N.H. Martin. 2019. Asymmetric introgression between fishes in the Red River basin of Texas is associated with variation in water quality. Ecology and Evolution. 9: 2083-2095. DOI: 10.1002/ece3.4901. 

Sung, Cheng-Jung, K.L. Bell, C.C. Nice, and N.H. Martin. 2018. Integrating Bayesian genomic cline analyses and association mapping of morphological and ecological traits to dissect reproductive isolation and introgression in a Louisiana Iris hybrid zone. Molecular Ecology 27(4) 959-978. DOI:10.1111/mec.14479 

Shaw, J.P., S.J. Taylor, M.C. Dobson, and N.H. Martin. 2017. Pollinator isolation in Louisiana iris: legitimacy and pollen transfer. Evolutionary Ecology Research 18: 429-441. 

Martin, N.H. and S.J. Taylor. 2013. Floral preference, flower constancy, and pollen transfer efficiency of the ruby-throated hummingbird (Archilochus colubris) in mixed arrays of Iris nelsonii and Iris fulva. Evolutionary Ecology Research 15: 783-792.  

Taylor, S.J., L.D. Rojas, S.W. Ho, N.H. Martin, 2013. Genomic collinearity and the genetic architecture of floral differences between the homoploid hybrid species Iris nelsonii and one of its progenitors, Iris hexagona. Heredity 110 (1): 63-70. 

Benedict, B.G. Modliszewski, J.L., A.L. Sweigart, N.H. Martin, and J.H. Willis. 2012. Mimulus sookensis (Phrymaceae), a new allotetraploid species derived from Mimulus guttatus and Mimulus nasutus. Madroño 59: 29-43. 

Ballerini, E.A., A.N. Brothers, S. Tang, S.J. Knapp, A. Bouck, S.J. Taylor, M.L. Arnold and N.H. Martin. 2012. QTL mapping reveals the genetic architecture of loci affecting pre- and post-zygotic isolating barriers in Louisiana Iris. BMC Plant Biology 12: 91. 

Taylor, S.J., K.J. AuBuchon, and N.H. Martin. 2012. Identification of floral visitors of Iris nelsonii. Southeastern Naturalist: 11: 141-144.  

Dobson, M.C., S.J. Taylor, M.L. Arnold and N.H. Martin. 2011. Patterns of herbivory and fungal infection in experimental Louisiana Iris hybrids. Evolutionary Ecology Research 13: 543-552.  

Taylor, S.J., R.W. Willard, J.P. Shaw, M.C. Dobson, and N.H. Martin. 2011. Differential response of the homoploid hybrid species Iris nelsonii (Iridaceae) and its progenitors to abiotic habitat conditions. American Journal of Botany 98: 1309-1316. 

Martin, N.H. and J.H. Willis. 2010. Geographic variation in postzygotic isolation and its genetic basis within and between two Mimulus species. Philosophical Transactions of the Royal Society B: Biological Sciences 365: 2469-2478.  

Tang, S., R.A. Okashah, S.J. Knapp, M.L. Arnold, and N.H. Martin. 2010. Reproductive isolation in Louisiana Irises: transmission ratio distortion. BMC Plant Biology 10: 48.  

Arnold, M.L. and N.H. Martin. 2010. Hybrid fitness across time and habitats. Trends in Ecology and Evolution 25: 530-536.  

Taylor, S.J., M.L. Arnold, and N.H. Martin. 2009. Genetic architecture of reproductive isolation in Louisiana Irises: hybrid fitness in nature. Evolution 63: 2581-2594.  

DeVries, P. J., G.T. Austin, and N.H. Martin. 2009. Estimating species diversity in a guild of Neotropical skippers (Lepidoptera: Hesperiidae) with artificial lures is a sampling problem. Insect Conservation and Diversity 2: 1-10.  

Arnold, M.L., S. Cornman, and N.H. Martin. 2008. Genetic exchange and the origin of adaptations – Prokaryotes to primates. Philosophical Transactions of the Royal Society B: Biological Sciences 363: 2813-2820. 

Martin, N.H., Y. Sapir, and M.L. Arnold. 2008. The genetic architecture of reproductive isolation in Louisiana Irises: pollination syndromes and pollinator preferences. Evolution 62: 740-752.  

A.L. Sweigart, N.H. Martin, and J.H. Willis, 2008. Hybrid origin of a new Mimulus species. Molecular Ecology 17: 2089-2100.  

P.J. DeVries, G.T. Austin, and N.H. Martin. 2008. Patterns of diversity and temporal activity in a mega-diverse community of rainforest skipper butterflies. Biological Journal of the Linnean Society 94: 723-736. 

Martin, N.H., A.C. Bouck, and M.L. Arnold. 2007. The genetic architecture of reproductive isolation in Louisiana Irises: Flowering Phenology. Genetics 175: 1803-1812. 

Martin, N.H. and J.H. Willis. 2007. Ecological divergence associated with mating system causes nearly complete reproductive isolation between sympatric Mimulus species. Evolution61: 68-82. 

Martin, N.H., A.C. Bouck, and M.L. Arnold. 2006. Detecting adaptive trait introgression between Iris fulva and Iris brevicaulis in highly-selective field conditions. Genetics 172: 2481-2489. 

Martin, N.H. 2004. Flower size preferences of the honeybee (Apis mellifera) foraging on Mimulus guttatus (Scrophulariaceae). Evolutionary Ecology Research 6: 777-782.