Climatic data collection
To characterize patterns of spatial environmental variation among the localities, the historical values (1970-2000) of 19 environmental variables (bio 1 - bio 19) and elevation (Elv) were obtained using the package raster v.2.7.15 and the Wordclim data of 2.5 arcmins (available at http://worldclim.org/ ). We tested for covariation among environmental variables using the vifcor () function from the “usdm” R package (Naime et al., 2014). Variables presenting no strong covariation (R <0.8; see Fitzpatrick and Keller, 2014) were conserved for subsequent analyses (Supplementary table 1).