DOI: 10.5061/dryad.qz612jm8z
title: Local versus broad scale environmental drivers of continental beta diversity patterns in subterranean spider communities across Europe

description: Macroecologists seek to identify drivers of community turnover
 (β-diversity) through broad spatial scales. Yet, the influence of local
 habitat features in driving broad-scale β-diversity patterns remains
 largely untested, due to the objective challenges of associating
 local-scale variables to continental-framed datasets. We examined the
 relative contribution of local- versus broad-scale drivers of continental
 β-diversity patterns, using a uniquely suited dataset of cave-dwelling
 spider communities across Europe (35–70° latitude). Generalized
 dissimilarity modeling showed that geographical distance, mean annual
 temperature, and size of the karst area in which caves occurred drove most
 of β-diversity, with differential contributions of each factor according
 to the level of subterranean specialization. Highly specialized
 communities were mostly influenced by geographical distance, while less
 specialized communities were mostly driven by mean annual temperature.
 Conversely, local-scale habitat features turned out to be meaningless
 predictors of community change, which emphasizes the idea of caves as the
 human accessible fraction of the extended network of fissures that more
 properly represents the elective habitat of the subterranean fauna. To the
 extent that the effect of local features turned to be inconspicuous, caves
 emerge as experimental model systems in which to study broad biological
 patterns without the confounding effect of local habitat features.
description: We compiled what we believe to be the first continental-scale geo-referenced dataset of subterranean spider communities across Europe. The dataset comprises data from 475 caves from 27 European countries, and covers a latitudinal range from 35° to 70°. In constructing the dataset, we deliberately choose caves for which we deemed the spider fauna to be exhaustively known and for which the morphological and environmental features were available, thus minimizing the number of missing data (‘NA’) in the dataset. Although we acknowledge that different sampling bias exists when it comes to estimate the diversity of species within subterranean habitats, by selecting only well-studied caves we assumed the sampling bias to be homogeneous within the caves included in the dataset. We associated high-resolution data to each cave, namely spider community composition along with information on local geomorphological and environmental features. The full dataset will be made available in a datapaper that is currently under review: Mammola S, Cardoso P, Angyal D, Balázs G, Blick T, Brustel H, Carter J, Ćurčić S, Danflous S, Dányi D, Déjean S, Deltshev C, Elverici M, Fernández J, Gasparo F, Komnenov M, Komposch C, Kováč L, Kunt K B, Mock A, Moldovan O T, Naumova M, Pavlek M, Prieto C E, Ribera C, Rozwałka R, Růžička V, Vargovitsh R S, Zaenker S, Isaia M. Continental data on cave-dwelling spider communities across Europe (Arachnida: Araneae). Biodivers. Data J., submitted. Here, we upload the databases elaborated for performing Generalized Dissimilarity Modellingin R, namelysite-by-environment (data_env.txt), and site-by-species matrices for troglophile (data_troglophiles.txt) and troglobiont (data_troglobionts.txt ) spiders, as well as the R code for generating the analyses (R_code.r).
description: Datasets: -data_env.txt =Environmental
 predictors formatted for generalized dissimilarity modeling.
 -data_troglophiles.txt = ‘gdm’ Site-Pair Table for
 troglophiles. -data_troglobionts.txt = ‘gdm’ Site-Pair
 Table for troglobionts. Data are provide as
 tab-delimited txt. Please refer to the main publication for a full
 description of the variables (Appendix S1) and analyses (Appendix
 S2).   Codes:
 R_code.r = R code for generating the analyses.