Conspicuous female signals have recently received substantial scientific
attention, but the degree to which female-specific selection drives
their evolution remains unclear. Species that express female-specific
phenotypic variation among populations represent a useful opportunity to
address this knowledge gap. White-shouldered fairywrens (Malurus
alboscapulatus) are tropical songbirds with a well-resolved phylogeny
where female, but not male, coloration varies allopatrically across
subspecies. We explored how four distinct signaling modalities, each
putatively associated with increased social selection, are expressed in
two populations that vary in competitive pressure on females. Females in
a derived subspecies (M. a. moretoni) have evolved more ornamented
plumage, more complex vocalizations, and shorter tails (a signal of
social dominance) relative to an ancestral subspecies (M. a. lorentzi)
with drab females. Moreover, in response to simulated territorial
intrusions broadcasting female song, female M. a. moretoni are more
aggressive and more coordinated with their mate in both movement and
vocalizations. These results suggest that correlated phenotypic shifts
in female color, morphology, song complexity, and behavior may have
occurred in response to changes in social selection, consistent with the
idea that female-specific selection has driven the evolution of these
signals.
Correlated evolution of distinct signals associated with increased social selection in female white‐shouldered fairywrens
