R. Alexander Pyron

R. Alexander Pyron

Robert F. Griggs Assistant Professor of Biology
Lisner Hall 414
Phone: 202-994-6616

Systematics of reptiles and amphibians; Theory and practice of statistical phylogenetics.

Current Research

My research focuses on theoretical and applied methods in statistical phylogenetics, using reptiles and amphibians as model groups. In an organismal context, I study the factors that drive speciation at local geographic scales, and the evolutionary forces responsible for broad-scale macroecological patterns in the distribution and diversity of extant species. I am also interested in statistical and analytical methodologies for divergence time estimation and phylogenetic inference using multi-locus datasets.


I am looking for motivated undergraduates, graduate students, and post-doctoral researchers to join my lab. I invite students to develop their own fully-fledged, independent research projects. Please contact me if you are interested.

The Pyron Lab at the George Washington University seeks a doctoral student for the Fall of 2016 who is interested in historical biogeography, phylogeography, and the theory and practice of systematics. This position is available under the new NSF Genealogy of Life project "VertLife Terrestrial: A complete, global assembly of phylogenetic, trait, spatial and environment characteristics for a model clade." The position will be based in the Biological Sciences Department at the George Washington University (http://www.gwu.edu).

I am looking for a student with an interest in macroevolution and macroecology, and with superior skills in phylogenetic analysis and models of trait evolution and diversification. Additional background in spatial analysis and informatics tools development is highly welcome. This position will primarily focus on reptiles and amphibians.


B.S., Piedmont College, 2004.
PhD., MS., MPhil., The City of New York University, 2009


Pyron, R.A. 2015. Post-molecular systematics and the future of phylogenetics. Trends in Ecology and Evolution 30(7):384-389.

Fry, B.G, Sunagar, K., Casewell, N., Kochva, E., Scheib, H., Wuster, W., Vidal, N., Young, B., Burbrink, F.T., Pyron, R.A., Vonk, F.J., Roelants, K., and T.N.W. Jackson. 2015. The origin and evolution of the Toxicofera reptile venom system. Chapter 1 in Venomous Reptiles And Their Toxins: Evolution, Pathophysiology And Biodiscovery (B. G. Fry, ed.). Oxford University Press, Oxford. 576p.

Betancur-R, R., Orti, G., and R.A. Pyron. 2015. Fossil-based comparative analyses revealancient marine ancestry erased by extinction in ray-finned fishes. Ecology Letters 18(5):441-450.

Longrich, N.R., Vinther, J., Pyron, R.A., Pisani, D., and J.A. Gauthier. Biogeography of worm lizards (Amphisbaenia) driven by end-Cretaceous mass extinction. Proceedings of the Royal Society B, Biological Sciences 282(1806): 20143034.

Arcila, D.K., Pyron, R.A., Tyler, J.C., Orti, G., and R. Betancur-R. 2015. An evaluation of fossil tip-dating versus node-age calibrations in tetraodontiform fishes (Teleostei: Percomorphaceae). Molecular Phylogenetics and Evolution 82(A):131-145.

Ohler, A., Amarasinghe, A.A.T., Andreone, F., Bauer, A., Borkin, L., Channing, A., Chuankern, Y., Das, I., Deuti, K., Fretey, T., Matsui, M., Pyron, R.A., Rodel, M.O., Segniagbeto, G.H., Vasudevan, K., and A. Dubois. 2014. DICROGLOSSIDAE Dubois, 1987 (Amphibia, Anura): proposed conservation. Bulletin of Zoological Nomenclature 71(4): 244-249.

Guo, P., Zhu, F., Liu, Q., Zhang, L., Li, J. X., Huang, Y. Y., and R.A. Pyron. 2014. Cryptic diversity and taxonomic revision of the Asian keelback snakes, genus Amphiesma (Serpentes: Colubridae: Natricinae). Zootaxa 3873(4): 425-440.

Pyron, R.A., Hendry, C.R., Chou, V.M., Lemmon, E.M., Lemmon, A.R., and F.T. Burbrink. 2014. Effectiveness of phylogenomic data and coalescent species-tree methods for resolving difficult nodes in the phylogeny of advanced snakes (Serpentes: Caenophidia). Molecular Phylogenetics and Evolution 81(1): 221-231.

Fenker, J., Tedeschi, L.G., Pyron, R.A., and C. Nogueira. 2014. Phylogenetic diversity, habitat loss and conservation priorities in South American pitvipers (Crotalinae: Bothrops and Bothrocophias). Diversity and Distributions 20(10): 1108-1119.

Pyron, R.A. 2014. Temperate extinction in squamate reptiles and the roots of latitudinal diversity gradients. Global Ecology and Biogeography 23(10): 1126-1134.

Pyron, R.A. 2014. Biogeographic analysis of amphibians reveals both ancient continental vicariance and recent oceanic dispersal. Systematic Biology 63(5): 779-797.
Pyron, R.A., Reynolds, R.G., and F.T. Burbrink. 2014. A taxonomic revision of boas (Serpentes, Boidae). Zootaxa 3846(2): 249-260.

Pyron, R.A., and V. Wallach. 2014. Systematics of the blindsnakes (Serpentes: Scolecophidia: Typhlopoidea) based on molecular and morphological evidence. Zootaxa 3829(1): 1-81.

Pyron, R.A., and F.T. Burbrink. 2014. Ecological and evolutionary determinants of species richness and phylogenetic diversity for island snakes. Global Ecology and Biogeography 23(8): 848-856.

Hendry, C.R., Guiher, T.J., and R.A. Pyron. Ecological differentiation and sexual selection drives sexual size-dimorphism in New World pitvipers (Crotalinae). Journal of Evolutionary Biology 27(4): 760-771.

Ruane, S., Bryson, R.W. Jr., Pyron, R.A., and F.T. Burbrink. 2014. Coalescent species delimitation in Milksnakes (genus Lampropeltis) and impacts on phylogenetic comparative analyses. Systematic Biology 63(2): 231-250.

Cooper, W.E. Jr., Pyron, R.A., and T.J. Garland Jr. 2014. Island tameness: living on islands reduces flight initiation distance. Proceedings of the Royal Society B, Biological Sciences 281(1777):20133019.

Pyron, R.A., and F.T. Burbrink. 2014. Early origin of viviparity and multiple reversions to oviparity in squamate reptiles. Ecology Letters 17(1): 13-21.

Pyron, R.A., and F.T. Burbrink. 2013. Phylogenetic estimates of speciation and extinction rate for testing ecological and evolutionary hypotheses. Trends in Ecology and Evolution 28(12): 729-736.

Pyron, R.A., and J.J. Wiens. 2013. Large-scale phylogenetic analyses reveal the causes of high tropical amphibian diversity. Proceedings of the Royal Society B, Biological Sciences 280(1770): 20131622.

Guo, P., Liu, Q., Zhang, L., Li, C., Pyron, R.A., Jiang, K., and F.T. Burbrink. 2013. Lycodon and Dinodon: one genus or two? Evidence from molecular phylogenetics and morphological comparisons. Molecular Phylogenetics and Evolution 68(1): 144-149.

Pyron, R.A., Burbrink, F.T., and J.J. Wiens. 2013. A phylogeny and updated classification of Squamata, including 4161 species of lizards and snakes. BMC Evolutionary Biology 13:93.

Abraham, R.K., Pyron, R.A., Zachariah, A., Ansil, B.R., and A. Zachariah. 2013. Two new genera and one new species of treefrog (Anura: Rhacophoridae) highlight cryptic diversity in the Western Ghats of India. Zootaxa 3640(2): 177-199.

Garda, A.A., Wiederhecker, H.C., Gainsbury, A.M., Costa, G.C., Pyron, R.A., Vieira, G.H.C., Werneck, F.P., and G.R. Colli. 2013. Microhabitat variation explains local-scale distribution of terrestrial Amazonian lizards in Rondônia, western Brazil. Biotropica 45(2): 245-252.

Pyron, R.A., Kandambi, H.K.D., Hendry, C.R., Pushpamal, V., Burbrink, F.T., and R. Somaweera. 2013. Genus-level molecular phylogeny of snakes reveals the origins of species richness in Sri Lanka. Molecular Phylogenetics and Evolution 66(3): 969-975.

Chen, X., Huang, S., Guo, P., Colli, G.R., Montes de Oca, A.N., Vitt, L.J., Pyron, R.A., and F.T. Burbrink. 2013. Understanding the formation of ancient intertropical disjunct distributions using Asian and Neotropical hinged-teeth snakes (Sibynophis and Scaphiodontophis: Serpentes: Colubridae). Molecular Phylogenetics and Evolution 66(1): 254-261.

Classes Taught

BISC 6211 - Biogeography

BISC 6214 - The Phylogenetic Basis of Comparative Biology