Meeting Abstract
Until recently female ornaments were thought be byproducts of selection for sexiness in males due to a shared autosomal genome. However, evolutionary transitions in ornamentation have occurred more often in females, often relatively rapidly, and typically in the direction of gaining ornaments. Recent work has begun to shed light on the adaptive significance of female ornaments, yet the mechanisms underlying these traits are unresolved. In males of many songbirds, seasonal increases in androgens initiate molt into ornamental plumage and onset of sexual behaviors. Female songbirds often express many of these “male typical” traits and circulate seasonally varying androgen titres. Yet, few studies have found a link between androgens and female ornaments, and the role of androgens in female organisms remains a contentious and perplexing issue. Here we explore the potential role of androgens in promoting ornamentation and sexual behaviors in a bird species with discrete female plumage morphs. White-shouldered fairy wren (Malurus alboscapulatus) males produce one plumage consisting of black with contrasting white shoulder patches (ornamented), whereas females can be cryptic brown (unornamented) or ornamented depending on the population. Unornamented females have lower baseline androgens than ornamented females, who circulate much lower titres than ornamented males. Intriguingly, male androgen titres also differ between populations, but in the opposite direction of females. We combine this dataset with behavior assays and preliminary results from an androgen supplementation experiment to address the role of androgens in phenotypic differentiation.
