Contrasted patterns of local adaptation to climate change across the range of an evergreen oak, Quercus aquifolioides

Long-lived tree species are genetically differentiated and locally adapted with respect to fitness-related traits, but the genetic basis of local adaptation remains largely unresolved. Recent advances in population genetics and landscape genomic analyses enable identification of putative adaptive loci and specific selective pressures acting on local adaptation. Here we sampled 60 evergreen oak (Quercus aquifolioides) populations throughout the species’ range and pool-sequenced 587 individuals at drought stress candidate genes. We analyzed patterns of genetic diversity and differentiation for 381 single nucleotide polymorphisms (SNPs) from 65 candidate genes and eight microsatellites. Outlier loci were identified by genetic differentiation analysis and genome–environment associations. The response pattern of genetic variation to environmental gradient was assessed by linear isolation by distance/environment tests, redundancy analysis and non-linear methods. SNPs and microsatellites revea...