Plumage color manipulation has no effect on social dominance or fitness in zebra finches

Colourful plumage ornaments may evolve because they play a role in mate choice or in intrasexual competition, acting as signals of species identity or of individual quality. The zebra finch (Taeniopygia guttata) is a model organism for the study of mate choice and its colourful plumage ornaments are thought to be used in both of these contexts. Numerous genetic colour variants have been described for this species, but they are rare in the wild. This raises the question whether discrimination against deviant phenotypes maintains the species’ uniform plumage colour (rare mate disadvantage). Further, comparison to closely related species suggests that the lack of colourful ornaments in female zebra finches is a derived condition. Male preferences for less ornamented females may have led to sexual dichromatism in the zebra finch. Here, we test the role of plumage ornaments experimentally by altering male and female colouration to mimic two types of naturally occurring genetic colour variant...