Molecular parallelism in signaling function across different sexually selected ornaments in a warbler

Abstract

Significance Ornaments are thought to signal the genetic quality of males to females choosing mates, but the qualities they signal and why they sometimes vary between populations are poorly understood. Here, we show, within a single warbler species, that two plumage ornaments signal similar aspects of male quality (e.g., immunity and oxidative balance) at the level of genetic functions, even though the ornament preferred by females differs between populations, involves different body parts, and is produced by different pigments (melanins and carotenoids). This parallelism at the functional level provides the flexibility for different types of ornaments to be used as signals of similar aspects of male quality, allowing for switches in female preferences between ornaments and potentially facilitating divergence and speciation.