DOI: 10.5061/dryad.47d7wm393
title: Ecological, genetic and evolutionary drivers of regional genetic differentiation in Arabidopsis thaliana

description: Background: Disentangling the drivers of genetic differentiation is one of
 the cornerstones in evolution. This is because genetic diversity, and the
 way in which it is partitioned within and among populations across space,
 is an important asset for the ability of populations to adapt and persist
 in changing environments. We tested three major hypotheses accounting for
 genetic differentiation—isolation-by-distance (IBD),
 isolation-by-environment (IBE) and isolation-by-resistance (IBR)—in the
 annual plant Arabidopsis thaliana across the Iberian Peninsula, the region
 with the largest genomic diversity. To that end, we sampled, genotyped
 with genome-wide SNPs, and analyzed 1,772 individuals from 278 populations
 distributed across the Iberian Peninsula. Results: IBD, and to a lesser
 extent IBE, were the most important drivers of genetic differentiation in
 A. thaliana. In other words, dispersal limitation, genetic drift, and to a
 lesser extent local adaptation to environmental gradients, accounted for
 the within- and among-population distribution of genetic diversity.
 Analyses applied to the four Iberian genetic clusters, which represent the
 joint outcome of the long demographic and adaptive history of the species
 in the region, showed similar results except for one cluster, in which IBR
 (a function of landscape heterogeneity) was the most important driver of
 genetic differentiation. Using spatial hierarchical Bayesian models, we
 found that precipitation seasonality and topsoil pH chiefly accounted for
 the geographic distribution of genetic diversity in Iberian A. thaliana.
 Conclusions: Overall, the interplay between the influence of precipitation
 seasonality on genetic diversity and the effect of restricted dispersal
 and genetic drift on genetic differentiation emerges as the major forces
 underlying the evolutionary trajectory of Iberian A. thaliana.
description: See Methods section in the manuscript.
description: DATA: Genetic and environmental data of 278 Arabidopsis thaliana
 populations and 1772 individuals.<br> The file has two sheets
 including the following information: 1. SNP data (240
 polymorphic nuclear SNPs):<br> 1st row: SNP name.<br> 2nd row:
 chromosome in which SNPs are located.<br> 3rd row: physical position
 of SNPs.<br> 4th row: genetic position of SNPs.<br> 5th row:
 collections of polymorphic SNPs (WHF: worldwide collection; CE: Central
 Europe; IP: Iberian Peninsula).<br> 6th row: empty.<br> 7th
 row: SNP name.<br> 1st column: names of variables, including
 population-individual codes after the empty row.<br> 2nd to 241st
 column: nucleotides (A, C, G or T).<br> Notes: all loci are
 homozygous.<br> Missing data = 9999. 2.
 Geographic and environmental data (29 variables):<br> 1st row:
 Population and variable names.<br> 1st column: population-individual
 codes.<br> 2nd column: longitude (degrees).<br> 3rd column:
 latitude (degrees).<br> 4th column: altitude (masl).<br> 5th
 to 23rd column: WordClim variables (code and self-explanatory
 name).<br> 24th to 29th column: CORINE variables (self-explanatory
 name).<br> 30th column: pH from The Soil Geographical Database from
 Eurasia.