X-linked and sex-specific selection during a climate mediated range-expansion in a damselfly

The X-chromosome and sex-specific selection can alter the evolutionary trajectory of species. Assessing these processes in a climate-induced range expansion can help us understand species’ persistence. The blue-tailed damselfly (Ischnura elegans) is expanding poleward across northern Europe in response to climate change. In this study we analysed 15,145 SNPs of 426 I. elegans along a 583 km range-expansion gradient in Sweden. Within a range-expansion context, we aim to explore signatures of sex-specific selection and use window-analysis to examine neutral and adaptive processes with a particular focus on X-linked effects. Statistical analyses performed covered sex-specific selection, clustering, outlier scans, window-analysis and gene annotation. We detected genetic signatures of sex-specific selection with a “release” in autosomal male-biased expressed genes. We showed genetic variation was maintained in X-linked regions despite decreases in autosomal regions, range expansion was stifled at range-edge due to maladaptation and admixture, and there was less than expected X-linked contribution to adaptation. In mid-latitudes we found local adaptation to courtship and sensory systems, and in high-latitudes we found local adaptation to stress response and development with a “release” of selection on mitochondrial activity. These results highlight the importance of the X-chromosome and sex-specific selection during climate-induced range expansions.