Chromosomal Inversion Associated With Diet Differences in Common Quails Sharing Wintering Grounds

Chromosomal inversions can contribute to genetic differentiation and ecological adaptation. In common quails (Coturnix coturnix), a large chromosomal inversion encompassing over 1200 genes is associated with key phenotypic traits, including increased body size, darker throat pigmentation, and reduced flight efficiency, which may influence migratory behavior. We hypothesized that the presence of resident common quails in the south of the Iberian Peninsula is the consequence of the high frequency of this chromosomal inversion, found in a high proportion of the breeding individuals in the region. We surveyed one wintering population in southern Spain and analyzed the genomic composition, morphology, and deuterium, nitrogen, and carbon stable isotope composition of primary feathers. Our results revealed the coexistence of birds with different karyotypes and morphologies that also differed in migratory behavior, as inferred from the comparison of the stable isotope signature in feathers. While quails with the inversion showed limited evidence of migratory movements, quails without the inversion seemed to have reached the area from other latitudes. Interestingly, our results also revealed that these migratory quails that reached this population in winter had differences in their diet. Thus, two separately evolving chromosomal lineages, characterized by the presence/absence of the inversion, coexist in the wintering area, leading to differences in morphology, behavior, and resource use. Due to the lack of recombination in the inversion, the divergence is expected to continue increasing.