Female and male plumage colour is linked to parental quality, pairing and extra-pair mating in a tropical passerine

Sexual selection has been proposed to drive the evolution of elaborate
phenotypic traits in males, which often confer success in competition or
mating. However, in many species both males and females display such
traits, although studies investigating selection acting in both sexes are
scarce. In this study, we investigated whether plumage ornamentation is
sexually selected in female and male lovely fairy-wrens Malurus amabilis,
a cooperatively breeding songbird. We found that female and male plumage
colour was correlated with parental quality but not with individual
quality and survival. We also found evidence of positive assortative
mating based on plumage colour. Microsatellite analyses of paternity
indicated that the lovely fairy-wren has high levels of extra-pair
paternity, with 53% of offspring (in 58% of broods, of 57% of females)
resulting from extra-pair mating. Female and male plumage colour did not
predict reproductive success or the proportion of extra-pair offspring in
their own nest, but less colourful males obtained higher extra-pair
paternity when paired with more colourful females, and gained overall
higher total paternity (own nest and other nests). We argue that plumage
colour may be under sex-specific selection, highlighting the importance of
looking at both sexes in studies of sexual selection and ornament
evolution. The current findings together with previous study, suggest that
plumage colour in female and male lovely fairy-wrens appears to be an
honest signal relevant in both intra and inter-sexual competition
contexts.