DOI: 10.5061/dryad.5gv12
title: Data from: Tests of species-specific models reveal the importance of drought in postglacial range shifts of a Mediterranean-climate tree: insights from integrative distributional, demographic and coalescent modelling and ABC model selection

description: Past climate change has caused shifts in species distributions and
 undoubtedly impacted patterns of genetic variation, but the biological
 processes mediating responses to climate change, and their genetic
 signatures, are often poorly understood. We test six species-specific
 biologically informed hypotheses about such processes in canyon live oak
 (Quercus chrysolepis) from the California Floristic Province. These
 hypotheses encompass the potential roles of climatic niche, niche
 multidimensionality, physiological trade-offs in functional traits, and
 local-scale factors (microsites and local adaptation within ecoregions) in
 structuring genetic variation. Specifically, we use ecological niche
 models (ENMs) to construct temporally dynamic landscapes where the
 processes invoked by each hypothesis are reflected by differences in local
 habitat suitabilities. These landscapes are used to simulate expected
 patterns of genetic variation under each model and evaluate the fit of
 empirical data from 13 microsatellite loci genotyped in 226 individuals
 from across the species range. Using approximate Bayesian computation
 (ABC), we obtain very strong support for two statistically
 indistinguishable models: a trade-off model in which growth rate and
 drought tolerance drive habitat suitability and genetic structure, and a
 model based on the climatic niche estimated from a generic ENM, in which
 the variables found to make the most important contribution to the ENM
 have strong conceptual links to drought stress. The two most probable
 models for explaining the patterns of genetic variation thus share a
 common component, highlighting the potential importance of seasonal
 drought in driving historical range shifts in a temperate tree from a
 Mediterranean climate where summer drought is common.
description: Microsatellite genotypes
 of canyon live oakCollecting localities of
 all individuals sampled and genotypes at 13 microsatellite loci. Asterisk
 (*): population excluded from analysis due to insufficient sample size;
 dagger (†): individual excluded from analysis due to incomplete data (&lt;
 10 successfully genotyped microsatellite loci).Microsatellite_genotypes.xlsxOccurrence records of canyon live oakLatitude and longitude of occurrence records used to construct ecological niche models. Citations for database sources and methods for filtering occurrence records prior to use are described in the Supplementary Methods.Occurrence_records.xlsxCustom Python scripts for iDDC modelsPython scripts used to generate customized input files for demographic and genetic simulations (see Materials and Methods for complete details). Descriptions of each script are provided in the ReadMe file. Scripts are slightly modified from original code written by Qixin He at the University of Michigan (current address: University of Chicago), provided here with permission.Custom_scripts.zip