Sex-linked genetic diversity and differentiation in a globally distributed avian species complex

Sex chromosomes often bear distinct patterns of genetic variation due to unique patterns of inheritance and demography. The processes of mutation, recombination, genetic drift and selection also influence rates of evolution on sex chromosomes differently than autosomes. Measuring such differences provides information about how these processes shape genomic variation and their roles in the origin of species. To test hypotheses and predictions about patterns of autosomal and sex‐linked genomic diversity and differentiation, we measured population genetic statistics within and between populations and subspecies of the barn swallow (Hirundo rustica) and performed explicit comparisons between autosomal and Z‐linked genomic regions. We first tested for evidence of low Z‐linked genetic diversity and high Z‐linked population differentiation relative to autosomes, then for evidence that the Z chromosome …