DOI: 10.5061/dryad.crjdfn3g7
title: Different drivers of diversification for body elongation and limb reduction in convergently snake-like lizards

description: This dataset includes numbers of digits, phalanges, and presacral
 vertebrae for 1386 species of squamate reptiles gathered from the
 literature. Each species also has clade and habitat classifications. From
 the manuscript: Convergence is the evolution of similar phenotypes often
 due to similar selective pressures or constraints limiting evolutionary
 options. Snake-like morphologies, characterized by elongated bodies and
 reduced limbs, have evolved repeatedly among vertebrates, including
 numerous times in squamate reptiles (lizards and snakes). It has been
 suggested that elongation facilitates locomotion through substrates while
 limb reduction typically occurs in clade-specific patterns, but this has
 not been tested. We compared the fit of a series of habitat-specific and
 clade-specific models for the evolution of digits, phalanges. and trunk
 vertebrae in lizards. We found that species inhabiting fossorial and
 cluttered habitats differed in numbers of vertebrae, digits, and phalanges
 from species in other habitats. A model with habitat-specific rates fit
 best for vertebral evolution, with sand swimmers, litter dwellers, and
 burrowers having higher rates of vertebral evolution than non-fossorial
 taxa. However, we found digits and phalanges evolved in a clade-specific
 manner, with higher rates of limb evolution in certain clades. This
 suggests that limb reduction in snake-like lizards is dictated by
 clade-specific constraints. In contrast, fossoriality appears to relax
 functional constraints on vertebral number, facilitating body form
 diversification. These results suggest that the relaxation of constraints
 may be an additional mechanism for convergent evolution.
description: # Different drivers of diversification for body elongation and limb
 reduction in convergently snake-like squamate reptiles Dataset DOI:
 [10.5061/dryad.crjdfn3g7](10.5061/dryad.crjdfn3g7) ## Description of the
 data and file structure Numbers of digits, phalanges, and trunk vertebrae
 for species of squamate reptiles were collected from the literature. ###
 Files and variables #### File:
 Snake-like\_Convergence\_Dataset\_Final.xlsx **Description:** A Microsoft
 Excel worksheet containing three tabs. 'Dataset' tab includes
 species names, clade and habitat classifications, and numbers of digits,
 phalanges, and trunk vertebrae. A column is provided to list the sources
 where morphological information came from, and another column for any
 changes made to the Zheng & Wiens (2016) phylogeny to fit species in
 the dataset. 'References' tab includes the full APA format
 citations for each source used for the dataset. 'Readme' tab
 includes descriptions of the data in each column of the
 'Dataset' tab. ##### Variables * Species * Clade (14):
 Classification for the full 14 clade models. Includes 14 squamate clades
 and an "Ancestral" group. Clades are: Dibamidae, Gekkota,
 Xantusiomorpha, Acontiinae, 'Scincinae1',
 'Scincinae2', 'Lygosominae1',
 'Lygosominae2', Gymnophthalmoidea, Amphisbaenia, Lacertidae,
 Anguimorpha, Iguania, and Serpentes. * Clade (7): Classification for the
 reduced 7 clade models. Includes 7 squamate clades and an
 "Ancestral" group. Clades are: Dibamidae, Gekkota, Scincomorpha,
 Lacertoidea, Anguimorpha, Iguania, and Serpentes. * Habitat (5):
 Classification for the full 5 habitat models. Habitat classifications are
 based on Rodda (2020). Habitats are: Arboreal, Terrestrial, Litter
 Dweller, Sand Swimmer, and Burrower. * Habitat (4): Classification for the
 reduced 4 habitat models. Habitat classifications are based on Rodda
 (2020). Habitats are: Arboreal, Terrestrial, Litter Dweller, and
 Fossorial. * Digits: Number of digits, ranging from 0 to 10. Entries
 marked "n/a" did not have digits data collected for this study.
 * Phalanges: Number of phalanges, ranging from 0 to 37. Entries marked
 "n/a" did not have phalangeal data collected for this study. *
 Presacrals: Number of presacral vertebrae, ranging from 14 to 293. Entries
 marked "n/a" did not have vertebral data collected for this
 study. * Morphology Sources: References for morphological data. * Changes
 to Zheng & Wiens (2016): Changes made to phylogeny to fit species from
 the dataset.