DOI: 10.5061/dryad.bc507
title: Data from: Ecological and phylogenetic variability in the spinalis muscle of snakes

description: Understanding the origin and maintenance of functionally important
 subordinate traits is a major goal of evolutionary physiologists and
 ecomorphologists. Within the confines of a limbless body plan, snakes are
 diverse in terms of body size and ecology, but we know little about the
 functional traits that underlie this diversity. We used a phylogenetically
 diverse group of 131 snake species to examine associations between habitat
 use, sidewinding locomotion, and constriction behavior with the number of
 body vertebrae spanned by a single segment of the spinalis muscle, with
 total numbers of body vertebrae used as a covariate in statistical
 analyses. We compared models with combinations of these predictors to
 determine which best fit the data among all species and for the advanced
 snakes only (N = 114). We used both ordinary least squares models and
 phylogenetic models in which the residuals were modeled as evolving by the
 Ornstein-Uhlenbeck process. Snakes with greater numbers of vertebrae
 tended to have spinalis muscles that spanned more vertebrae. Habitat
 effects dominated models for analyses of all species and advanced snakes
 only, with the spinalis length spanning more vertebrae in arboreal species
 and fewer vertebrae in aquatic and burrowing species. Sidewinding
 specialists had shorter muscle lengths than non-specialists. The
 relationship between prey constriction and spinalis length was less clear.
 Differences among clades were also strong when considering all species,
 but not for advanced snakes alone. Overall, these results suggest that
 muscle morphology may have played a key role in the adaptive radiation of
 snakes.
description: Appendix S1:
 Phylogenetic tree file, PDIThis file (spinal_1.pdi)
 of the phylogenetic tree (shown in Fig. 1) was produced in the DOS
 PDTREE.EXE program (Garland et al., 1999; Garland & Ives, 2000). The
 two-letter codes correspond to the “PDICode” column in the raw data file
 (Appendix S4).spinal_1.pdiAppendix S2: Phylogenetic tree file, DSCThis phylogenetic tree in DSC format (SPINAL_1_DSC_out_from_Excel.dsc), which was input to the RegressionV2.m program in Matlab for our analyses. The order of the columns and rows corresponds to the order of species in our data files (Appendices S4-6). The file was originally created in the DOS PDDIST.EXE program (Garland & Ives, 2000), from the file spinal_1.pdi (Appendix S1), with headers, then edited in Excel to verify the order and to remove headers.SPINAL_1_DSC_out_from_Excel.dscAppendix S3: Full model comparisonFull tables (AppendixS3_3_Tonini.xlsx) of alternate regression models showing all possible models (including those with zero support based upon criteria described in the Methods) for all species (N = 131) in one sheet and for caenophidians only (N = 114) in the other. † Evidence Ratios greater than 10,000AppendixS3_3_Tonini.xlsxAppendix S4: Raw dataRaw data used for the analysis (data_raw_JLT_8.xlsx).data_raw_JLT_8.xlsxAppendix S5: Data file for analysis of all speciesThis text file of data for all species (data_Matlab_JLT_8.txt) was input to the RegressionV2.m program in Matlab for our analyses. The order species corresponds to the order in the DSC phylogeny file (Appendix S2).data_Matlab_JLT_8.txtAppendix S6: Data file for analysis of Caenophidia onlyThis text file of data for the Caenophidia only (data_Matlab_JLT_8_Caenophidia.txt) was input to the RegressionV2.m program in Matlab for our analyses. The order species corresponds to the order in the DSC phylogeny file (Appendix S2).data_Matlab_JLT_8_Caenophidia.txt