Evolution of patterned plumage as a sexual signal in estrildid finches

Colour patterns, such as bars or dots, that cover the body surface of animals are generally thought to play roles in signalling and camouflage. In birds, however, the macroscopic aspects of plumage colouration are less well understood, as past studies typically described plumage colourations by using spectrophotometric analyses. To provide insight into the evolution of plumage patterns as sexual signals, we characterised interspecific and intersexual variations in the plumage patterns of estrildid finches and tested their associations with other courtship signals and life-history traits using a comparative phylogenetic approach. Our results support the idea that plumage patterns in estrildids are favoured by sexual selection because large-sized conspicuous plumage patterns are possessed by species with an elaborate courtship dance. These plumage patterns may also play roles in social signalling because patterns are more conspicuous in species with intraspecific brood parasitism. We pred...