Never underestimate the power of phylogenetics: macroevolution of New World pitviper venom

Rautsaw, Rhett

rrautsa@g.clemson.edu

Parkinson, Chris

Department of Biological Sciences

Clemson University

Clemson, SC 29634

Competition is a critical selective force for diversification; however, empirical studies on its role in promoting differentiation of adaptive phenotypes have largely been limited to small spatial and taxonomic scales. Here, we test the effect of competition on the evolution of pitviper venoms – a cross-continental radiation of venomous snakes each with tens to hundreds of individual toxins varying in expression, composition, and overall complexity among species. Using our novel phylogenomic reconstruction and >500 venom gland transcriptomes, we reveal that venom phenotypes diverge when multiple species coexist in a given area through time. Furthermore, we find that pitviper communities have evolved to maximize functional diversity despite comparatively low phylogenetic diversity, suggesting an evolutionary response of venom rather than communities accumulating phylogenetically diverse species. Together, these findings support competition as a likely selective pressure driving venom diversification in pitvipers.