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.

Biodiversity Conservation is Urgent and Important, Now and for the Future

In a recent OpEd (22 Nov 2017) in the Washington Post, I attempted to lay out an overview of the 5 mass extinctions in relation to the present-day Sixth Extinction, and relate the lessons from the past to a vision of the future of conservation and a recovery from the anthropogenic degradation of Earth. In the brief space of 1,900 words, I failed to make my views sufficiently clear and coherent, and succumbed to a temptation to sensationalize parts of my argument. Furthermore, I made the mistake of not showing the piece to my colleagues at GWU first; their dismay mirrored that of many in the broader community. As I’ve explained to them, and now I wish to explain to the field at large, my views and opinions were not accurately captured by the piece, and I hope the record can now be corrected. In particular, the headlines inserted for the piece for publication said "We don't need to save endangered species," and that "we should only worry about preserving biodiversity when it helps us." I did not write these words, I do not believe these things, and I do not support them.

I attempted to integrate multiple fields and viewpoints from evolution, ecology, and conservation, some of which I have the expertise to discuss in depth, and others of which I do not. Therefore, I cavalierly glossed over several complex issues in a way that did not represent them accurately or enhance a robust, consequential debate. Regardless of particular arguments I made regarding when and where biodiversity conservation is necessary or appropriate, I fully support both legislative and scientific efforts for conservation and preservation of biodiversity. I have researched the effects of climate change and extinction risk on reptiles and amphibians for over a decade. I am saddened by the fragmentation of habitat and the decline of the planet's amazing biodiversity at the numerous field sites I have visited. In no way do I condone extinction, or the exploitation of the natural environment, for short-term gain. Researchers engaged in biodiversity conservation have been some of my closest friends and colleagues, and their reaction to the piece and the perceived insult and attack on their work saddens me immensely.

What I intended to express and to bring to the public consciousness, is a merging of the timescales: getting people to think from the distant past into the vague future at the geological scale of evolutionary time, and across the ecological time that affects us as humans. There will likely come a day when there are no longer humans on earth, during this decline the remaining biodiversity will likely blossom again as it has done repeatedly through time. Then, there will likely be a Seventh Extinction, an Eighth, a Ninth. This is a powerful perspective, and one that contextualizes the drastic need for short-term conservation efforts, so that humanity does not go extinct as a result of our short-sighted exploitation of the biosphere.

The other point I tried to lay bare is the inevitability of more anthropogenic extinctions; many, many more species will go extinct soon, despite our best efforts, and this is an eventuality with which we have to deal. Our impacts in the short term are vast and negative. Therefore, in the face of inexorable extinction from a combination of factors including habitat loss and existentially threatening climate change, both of which we are causing, it is imperative that we engage in conservation to create a biodiverse, stable world, for ourselves and for future generations. The conclusion that I attempted to draw from this is that from the coming billions of people soon to be added, more habitat conversion, more ecological impact, more global change, more extinction will take place. This is whole-scale unstoppable although we may be able to make some impacts. I don't want species to go extinct, nobody does, but many will. So, how are we to deal with this?

I tried to conclude by illustrating the pressing need to focus on what we can control: emissions, pollution, renewable energy, sustainable agriculture, etc.. Initiatives like the ESA, CBD, and CITES have made great strides to protect imperiled biodiversity worldwide. Numerous areas of the world provide hopeful models for future ecological stability and sustainability, such as Costa Rica, running on ~100% renewable energy. Much of Europe, the United States and Canada, Australia and New Zealand, or Japan, with high environmental security (relatively speaking) and standards of living, represent a vision for the future for both humanity and biodiversity. Achieving these standards won’t be easy, and will require great financial and logistical commitments and technological innovation, as our lifestyles in the developed world represent huge amounts of resource consumption. Darker implications of things such as conservation triage, development vs. protection, and the "acceptability" of extinction are omnipresent and endemic to the world we live in, and will continue to be hotly debated.

My own view, embraced wholeheartedly and backed up by my lifetime's scientific work, is that there is a clear and pressing need for the comprehensive conservation of biodiversity. The process of extinction may be amoral (at least, extinctions not caused by humans), but I didn't intend to state that we had no moral obligation to our environment. Biodiversity conservation is needed so that the greatest possible amount of the biosphere is preserved intact through the Sixth Extinction, for two reasons. First is to support a burgeoning global population of humans over the next few centuries, while technologies for sustainability and renewable energy are enhanced, and ecologically stable co-existence is brought to the fore. Every human being deserves a safe, stable, secure, and happy life. Second is to promote the inevitable long-term recovery from the Sixth Extinction that will occur over millions of years in the future, either in the presence of a sustainable human population, or in the eventuality that humanity goes extinct.

My intent was to add shape and perspective from a long-term evolutionary viewpoint to the discussions on effective conservation actions and priorities for public policy, not to undermine them. I humbly ask that my intentions be judged by pointing to my scientific research, steeped in biodiversity discovery and analysis, with many publications on direct conservation topics and many more to come on the global threats affecting reptiles and amphibians. Many readers found a nihilistic viewpoint in my piece, but I deeply believe in and promote a philosophy of global compassion for the biosphere and humanity, that holds hope for prosperity and diversity in the future, transcending the inevitable degradation that our short-term impacts are causing. Ultimately, life will continue on in some way, with or without us. Life itself is unlikely to end in the Sixth Extinction. We can work now to ensure the best possible outcome of this tenuous and unstable passage. As I stated at the end: The Tree of Life will continue branching without us, even if we prune it back. The question is: how will we live in the meantime?



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