Italian sparrows expand our understanding of hybridization and local adaptation.   Nature: Ecology & Evolution recently published an online article which investigated the hybrid genomes of Italian sparrows (Passer italiae) on islands in the Mediterranean.  The authors tested the extent to which hybrid genomes are free to evolve by sequencing the genomes of hybrids on four different islands.  They conclude that candidate genes for beak shape (FGF10) and plumage (wnt7a) vary considerably between novel and fully functional hybrids, and that hybrid variations are expected to have arisen independently.  They also find that there are limits on variation in hybrids, most likely caused by genomic regions inherited from the same parent species, and these genes are over-represented on the Z chromosome.  Limits are imposed by incompatibility of candidate loci, and include DNA-repair and mitonuclear genes in Italian sparrows.  The authors find that this may influence introgression on these genes, as there is a reduction of introgression on sex chromosomes.  The take-away includes an identification of candidate genes for reproductive isolation in Italian sparrows.

Find the Nature: Ecology and Evolution article here