Phylogenetics of the lizard genus Tropidurus (Squamata: Tropiduridae: Tropidurinae): direct optimization, descriptive efficiency, and sensitivity analysis of congruence between molecular data and morphology.

By use of the technique of direct optimization the phylogenetics of the cis-Andean lizard genus Tropidurus were examined on the basis of both molecular (ca. 1.04 kb of sequences from 12S rDNA, valine tDNA, and 16S rDNA) and morphological (93 characters) data. Although equal weighting of all parsimony cost functions logically must maximize descriptive efficiency and explanatory power of all evidence, a sensitivity analysis demonstrated that equal weighting of indels, transitions, transversions, and morphological change provided the most congruent solution between the molecular and the morphological data partitions. The position of Uranoscodon is resolved as the sister taxon of the remaining members of the Tropidurinae. Plica, Uracentron, and Strobilurus, previously considered synonyms of Tropidurus, are resurrected; the group of these three genera form the sister taxon of the former Tropidurus nanuzae group (herein named Eurolophosaurus) plus Tropidurus sensu stricto (composed of the T. bogerti, T. semitaeniatus, T. spinulosus, and T. torquatus groups, herein diagnosed).

The role of habitat shift in the evolution of lizard morphology: evidence from tropical Tropidurus.

We compared morphology of two geographically close populations of the tropical lizard Tropidurus hispidus to test the hypothesis that habitat structure influences the evolution of morphology and ecology at the population level. T. hispidus isolated on a rock outcrop surrounded by tropical forest use rock crevices for refuge and appear dorsoventrally compressed compared with those in open savanna. A principal components analysis revealed that the populations were differentially distributed along an axis representing primarily three components of shape: body width, body height, and hind-leg length. Morphological divergence was supported by a principal components analysis of size-free morphological variables. Mitochondrial DNA sequences of ATPase 6 indicate that these populations are closely related relative to other T. hispidus, the rock outcrop morphology and ecology are derived within T. hispidus, and morphological and ecological divergence has occurred more rapidly than genetic divergence. This suggests that natural selection can rapidly adjust morphology and ecology in response to a recent history of exposure to habitats differing in structure, a result heretofore implied from comparative studies among lizard species.

Molecular homology assessment and phylogeny in the lizard family opluridae (Squamata: Iguania).

The effect of utilizing secondary structure on multiple alignment and phylogeny reconstruction was examined for the mitochondrial 12S ribosomal RNA and valine transfer RNA genes in the lizard family Opluridae. Computer-generated multiple alignments were performed under parsimony using gap costs of 1-10 both with and without reference to secondary structure. Alignments performed without secondary structure resulted in disruption of positional homology in some stems at all gap costs. Number of misaligned stem positions increased with gap cost. Phylogenetic analyses of multiple alignments without secondary structure recovered a well-supported morphological tree for five gap costs, and this was the single most parsimonious tree only for a gap cost of 1. Computer-generated multiple alignments using secondary structure to maintain positional homologs in stems recovered the morphological tree over all gap costs, and this was the single most parsimonious tree for 8 of 10 gap costs. The combined morphological and molecular data produced a single most parsimonious oplurid tree that was congruent with the morphological tree over all gap costs. Chalaradon madagascariensis is the sister taxon of Oplurus, which itself contains two clades: one with the arboreal Oplurus cuvieri and Oplurus cyclurus and the other with the saxicolous Oplurus grandidieri, Oplurus fierinensis, Oplurus quadrimaculatus, and Oplurus saxicola.