The A rctic skua ( S tercorarius parasiticus ) is a classic example of an avian plumage polymorphism, with variation in melanin‐based ventral plumage coloration defining pale, intermediate and dark morphs in adults of both sexes. However, despite several decades of field research, there is an incomplete understanding of how the polymorphism in ventral plumage colour is maintained and the selective forces involved. Here, we inv...

Aim To investigate the intra‐specific genetic divergence and phenotypic diversification in O ophaga granulifera , analysing phylogeographical patterns, population structure, coloration and traits potentially involved in reproductive isolation. Location Costa Rica. Methods Our phylogeographical analysis used the mitochondrial genes cytochrome b and 16S. We sequenced the two markers in 28 individuals belonging to 10 populations...