DOI: 10.5061/dryad.fd0gb
title: Data from: Environmental constraints on the compositional and phylogenetic beta-diversity of tropical forest snake assemblages

description: The ongoing biodiversity crisis increases the importance and urgency of
 studies addressing the role of environmental variation on the composition
 and evolutionary history of species assemblages, but especially the
 tropics and ectotherms remain understudied. In regions with rainy summers,
 coexistence of ectothermic species may be determined by the partitioning
 of the climatic niche, since ectotherms can rely on water availability and
 thermoregulatory behaviour to buffer constraints along their climatic
 niche. Conversely, ectotherms facing dry summers would have fewer
 opportunities to climatic niche partitioning and other processes rather
 than environmental filtering would mediate species coexistence. We used
 218 snake assemblages to quantify the compositional (CBD) and phylogenetic
 (PBD) beta-diversity of snakes in the Atlantic Forest (AF) hotspot. We
 identify two AF regions with distinct climatological regimes: dry summers
 in the northern-AF and rainy summers in the southern-AF. While accounting
 for the influence of multiscale spatial processes, we disentangle the
 relative contribution of thermal, water-related, and topographic
 conditions in structuring the CBD and PBD of snake assemblages, and
 determine the extent in which snake assemblages under distinct
 climatological regimes are affected by environmental filtering. Thermal
 conditions best explain CBD and PBD of snakes for the whole AF, whereas
 water-related factors best explain the structure of snake assemblages
 within a same climatological regime. CBD and PBD patterns are similarly
 explained by spatial factors but snake assemblages facing dry summers are
 more affected by spatial processes operating at fine to intermediate
 spatial scale whereas those assemblages in regions with rainy summers have
 a stronger signature of coarser-scale processes. As expected,
 environmental filtering plays a stronger role in southern-AF than
 northern-AF, and the synergism between thermal and water-related
 conditions is the key cause behind this difference. Differences in
 climatological regimes within the tropics may affect processes mediating
 species coexistence. The role of broad-scale gradients (e.g. temperature,
 precipitation) in structuring tropical ectothermic assemblages is greater
 in regions with rainy summers where climatic niche partitioning is more
 likely. Our findings highlight the potential stronger role of biotic
 interactions and neutral processes in structuring ectothermic assemblages
 facing changes towards warmer and dryer climates.
description: R-scriptThis is the R-script needed to reproduce the analysis of drivers of compositional and phylogenetic beta-diversity in Atlantic Forest snake assemblages.Moura_et_al_Supporting_Information_Appendix.RRaw dataThis csv file contains all raw data needed to run the R-script provided in this digital repository. Briefly, the first row of this file is the heading, and the next 218 rows correspond to the values of geographic coordinates (decimal degrees), species richness (integer), phylogenetic diversity (numeric), dissimilarity matrices (based on Simpson Index and PhyloSor-sim), number of survey methods (integer), number of sampling period (integer, years), survey methods (eigth dummy variables), bioclimatic space (factor, northern-AF = 1; southern-AF = 2), environmental variables (12 predictors related to thermal, water, and topographic conditions), spatial filters (58 distance-based Moran's Eigenvector Maps), and phylogenetic structure (mean pairwise phylogenetic distance within snake assemblages).Moura_et_al_Supporting_Information_Appendix.csv