Diversification of North American natricine snakes

Abstract

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.

Female‐biased gape and body‐size dimorphism in the New World watersnakes (tribe: Thamnophiini) oppose predictions from Rensch's rule

“…We used the function phylosig in the R package "phytools" (Revell, 2012) with the standard 1,000 simulations for the random test to yield enough power to determine significance. We used the most recent dated species tree of Thamnophiini (Data S2) from McVay et al (2015) to account for phylogenetic independence. We used the most recent dated species tree of Thamnophiini (Data S2) from McVay et al (2015) to account for phylogenetic independence.…”

“…We removed phylogenetic nonindependence using phylogenetic independent contrasts (PIC) in the R package (R Core Team, 2018) "Ape" (Paradis, Claude, & Strimmer, 2004). We used the most recent dated species tree of Thamnophiini (Data S2) from McVay et al (2015) to account for phylogenetic independence. To examine relationships between traits for testing SSD, we used the model II reduced/standardized major axis regression, reviewed in Smith (2009), which was used to study allometry with Rensch's rule in Wu, Jiang, Huang, and Feng (2018) in the R package "smatr" (Warton et al, 2012).…”

“…These snakes have been well-studied ecologically, behaviorally, morphologically, and phylogenetically and are a prominent feature of the snake fauna of North America (Burbrink, Chen, Myers, Brandley, & Pyron, 2012;Gibbons & Dorcas, 2004;Guo et al, 2012;McVay, Flores-Villela, & Carstens, 2015;Rossman, Ford, & Seigel, 1996), though the evolution of SSD across this group is unknown. Using a phylogenetic approach, we determine if SSD is concentrated in specific clades of watersnakes or if they are randomly distributed across the tree.…”

“…Using a phylogenetic approach, we determine if SSD is concentrated in specific clades of watersnakes or if they are randomly distributed across the tree. These snakes have been well-studied ecologically, behaviorally, morphologically, and phylogenetically and are a prominent feature of the snake fauna of North America (Burbrink, Chen, Myers, Brandley, & Pyron, 2012;Gibbons & Dorcas, 2004;Guo et al, 2012;McVay, Flores-Villela, & Carstens, 2015;Rossman, Ford, & Seigel, 1996), though the evolution of SSD across this group is unknown. Our results help understand if increases or decreases in SSD follow Rensch's rule, are associated with reproduction, and are reveal shared changes in particular groups of these snakes.…”

To what extent do new fossil discoveries change our understanding of clade evolution? A cautionary tale from burying beetles (Coleoptera:Nicrophorus)

“…We investigated whether lineages diversified rapidly in their early stage, and secondly reached an equilibrium meaning that diversity is saturated at the Present as niches become occupied and diversification rates slowed down (McVay, Flores-Villela & Carstens, 2015;Peña et al, 2015). We used the method of Etienne et al (2012) to explore the effect of diversity on speciation and extinction rates.…”