Diversification of North American natricine snakes JOHN D. MCVAY 1 *, OSCAR FLORES-VILLELA 2 and BRYAN CARSTENS 3 1 Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA 2 Facultad de Ciencias, Museo de Zoologia, Universidad Nacional Autonoma de Mexico, Circuito Extrior de CU, Mexico, DF, 04510, Mexico 3 Department of Evolution, Ecology and Organismal Biology, The Ohio State University, 318 W. 12th Avenue, Columbus, OH, 43210-1293, USA Received 14 November 2014; revised 31 March 2015; accepted for publication 31 March 2015 The phylogeny of thamnophiine snakes has not been fully resolved, largely because previous phylogenetic estimates have been based on incomplete taxon sampling or relied solely on mitochondrial sequence data. To address this deficiency, we collected data from multiple autosomal loci collected from 50 taxa before estimating the most robust phylogeny of Thamnophiini to date. Our findings clarify the relationships of taxa not previously included in molecular analyses and also lend evidence to previously recommended taxonomic revisions. Differences in topological estimates between competing models of evolution were minimal and not strongly supported; however, a multispecies coalescent model of evolution was highly favoured over a concatenated model based on marginal likelihood estimates. Additionally, we estimated the timing of divergence among the three major lineages to have occurred during the Miocene period (approximately 11–14 Mya), followed by a decline in speciation rates in all major lineages. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 116,1–12. ADDITIONAL KEYWORDS: Bayes factors – multilocus nuclear – path sampling – Thamnophiini. INTRODUCTION Although molecular phylogenetic estimates provide vital data pertaining to the relationships among organisms, the utility of phylogenetic work is enhanced when the phylogenies are incorporated into downstream analyses. For example, comparative methods (i.e. the optimization of organismal features on the phylogenetic estimate) can provide insights regarding phenotypic evolution, particularly when phylogenetic independent contrasts (Felsenstein, 1985) are utilized. Understanding the timing of evolu- tion by tracking rates of cladogensis can improve our understanding of species diversification. In addition to providing a historical context for interpreting the evolution of organismal features, phylogenies aid the researcher in understanding branching patterns and identifying the factors that promoted diversification. When combined, analytical tools that track character state evolution and the diversification of lineages through time improve our comprehension of both the pattern and process of evolutionary diversification. In the present study, we apply these tools to the thamno- phiine snakes, a group of vertebrates that have diver- sified into a variety of feeding niches, aiming to learn about the timing of the radiation and the evolution of feeding specialization in this group. Within the macrostomatan snakes, Thamnophiini (58 currently recognized species) represents the natr- icine subfamily of colubrid snakes in the Western hemisphere. This large radiation is traditionally clas- sified (based largely on morphology) into nine genera that span from Canada to Costa Rica and occupy a variety of montane to estuarine habitats. Many thamnophiine snakes are diet specialists, including those whose prey choice is restricted to soft prey, such as earthworms and slugs, and those that prefer hard prey, such as crayfish. Most species are closely associated with water, either as their primary habi- tat or as a source of prey for both aquatic and terres- trial foragers (Gibbons & Dorcas, 2004; Rossman, Ford & Seigel, 1996). Molecular phylogenetic data not only support many previously hypothesized clades, but also suggest that several of the clades inferred from morphological data are paraphyletic. Notable examples of paraphyly include the inclusion *Corresponding author. E-mail: johndmcvay@gmail.com 1 © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 116, 1–12 Biological Journal of the Linnean Society, 2015, 116, 1–12. With 3 figures. Downloaded from https://academic.oup.com/biolinnean/article/116/1/1/2447903 by guest on 02 July 2022