Conclusions
In this study on genomic adaptation of a small mammal to a pan-European climate gradient, we have shown that both geographic population structure and climate play important roles in explaining neutral genetic differentiation across the bank vole range. Genetic variation among candidate loci was mainly explained by variation in annual mean temperature, highlighting its importance for climate adaptation in the bank vole. We identified 74 genes that showed evidence of spatially varying selection and whose functional annotation suggested that energy homeostasis and response to pathogen infection are important targets of spatially varying selection in the bank vole. We propose to further investigate the functional significance of the identified genes, e.g., through common garden experiments and involving gene expression analysis, as they represent good candidates for local adaptation. Future studies should also look for spatial variation in physiological traits related to energy homeostasis or the immune system to ultimately link genetic variation, organismal physiology, and fitness traits in locally adapted populations.