Abstract
Evidence for spatially varying selection and adaptive variation can
provide insight into a species’ ability to adapt to different
environments. However, despite recent advances in genomics, it remains
difficult to detect footprints of spatially varying selection in natural
populations. Here we analysed ddRAD sequencing data (21,892 SNPs) in
conjunction with geographic climate variation to search for signatures
of adaptive differentiation in twelve populations of the bank vole
(Myodes/Clethrionomys glareolus) distributed across Europe. To identify
the loci subject to spatially varying selection and associated with
climate variation, we applied multiple genotype-environment association
(GEA) methods, two univariate and one multivariate, and controlled for
the effect of population structure. In total, we identified 213
candidate adaptive loci, 74 of which were located within genes. In
particular, we identified signatures of selection in candidate genes
with functions related to lipid metabolism and the immune system. Using
the results of redundancy analysis (RDA), we demonstrated that
population history and climate have joint effects on the genetic
variation in the pan-European metapopulation. Furthermore, by examining
only candidate loci, we found that annual mean temperature is an
important factor shaping adaptive genetic variation in the bank vole. By
combining landscape genomic approaches, our study sheds light on
genome-wide adaptive differentiation and the spatial distribution of
variants underlying adaptive variation in bank voles that are influenced
by local climate.