Molecular Systematics of the Leptodeirini (Colubroidea: Dipsadidae) Revisited: Species-tree Analyses and Multi-locus Data
Cat-eyed snakes (Leptodeira) were thought to be closely related to nightsnakes (Hypsiglena and Pseudoleptodeira) based on morphology and immunological data, which allied these genera with blunt-headed vine snakes (Imantodes) and the Cloud Forest Snake (Cryophis hallbergi ). We collected sequence data from six protein-encoding nuclear loci (SLC30A1, ZEB2, FSHR, NTF3, DNAH3, and PNN; 4149 bp) and additional mtDNA data (nad5; 955 bp) added to published cob and nad4 (total 2387 bp mtDNA) from these and other rear-fanged, mildly venomous snakes that prey on vertebrates (frogs and lizards) and from several other dipsadine genera (Dipsas, Sibon, and Atractus) that prey on invertebrates (goo-eaters). We analyzed relationships using concatenation and a coalescent species-tree method. When analyzed separately, using either concatenation or coalescent methods, nuclear data support a different overall topology from the mtDNA data. Like the mtDNA data, the nuclear data support the Leptodeira + Imantodes relationship, but instead place this clade more closely to the goo-eaters, with the nightsnakes as the basal divergence in the group. When the data are combined in concatenation analyses, the more variable mtDNA data appear to overwhelm the nuclear data, but not under the coalescent model.Abstract
Likelihood analyses for each nuclear locus. Cladograms are shown and bootstrap support values on nodes >50% are indicated; phylograms are shown in the lower left because short branch lengths obscured visualization of the structure. Using “ladderise” right standardized tree order within each tree.
Phylogenies based on nuclear loci (SLC30A1, ZEB2, FSHR, NT3, DNAH3, and PNN; 2387 bp) using: (A) Concatenated analyses with MrBayes; and (B) Coalescent analyses with BEST. Clade names: L = Leptodeirini, N = nightsnakes, G = goo-eaters. Posterior probability (Pp) values >0.50 are shown above the node/bar. Node with solid circle is referred to in text.
Phylogenies based on mtDNA and nuclear data combined using: (A) Concatenated Bayesian analyses of the mtDNA data (cob, nad4, nad5; 2387 bp) combined with the nuclear loci (SLC30A1, ZEB2, FSHR, NTF3, DNAH3, PNN; 4149 bp; ttl. = 6536 bp). When analyzed separately, the mtDNA revealed a nearly identical topology; the asterisk identifies a polytomy where topologies differed. Pp values >0.50 are shown above the node/bar for the mtDNA only, and below the node/bar for the combined analyses; nodes labeled with one value received Pp = 1.0 for both analyses. (B) Coalescent analyses with BEST of the combined mtDNA and nuclear data. Clade names: L = Leptodeirini, N = nightsnakes, G = goo-eaters, and Pp values >0.50 are shown. Solid circle identifies clade referred to in text.
Simplified cladograms based on mitochondrial data (A), and mtDNA and nuclear data combined (B). Tree B is a strict consensus between the concatenated likelihood and Bayesian analyses, and the BEST analyses. Numbers above generic names indicate estimated number of species if more than one, dashed lines indicate inferred placement for dipsadine genera that were not included in this study, dentition and diet traits are mapped on the trees (following Mulcahy, 2007). Clade names used throughout this study: L = Leptodeirini, N = nightsnakes, G = goo-eaters.
Contributor Notes
Associate Editor: T. W. Reeder.