Inferring selection in instances of long‐range colonization: the Aleppo pine (Pinus halepensis) in the Mediterranean Basin

Teasing apart the effects of natural selection and demography on current allele frequencies is challenging, due to both processes leaving a similar molecular footprint. In particular, when attempting to identify selection in species that have undergone a recent range expansion, the increase of genetic drift at the edges of range expansions (“allele surfing”) can be a confounded factor. To address this potential issue, we first assess the long-range colonisation history of the Aleppo pine across the Mediterranean Basin, using molecular markers. We then look for single nucleotide polymorphisms (SNPs) involved in local adaptation using: (i) environmental correlation methods (Bayenv2), focusing on bioclimatic variables important for the species’ adaptation (i.e. temperature, precipitation and water availability); and (ii) FST-related methods (PCAdapt). In order to assess the rate of false positives caused by the allele surfing effect, these results are compared with results from simulated S...