Speciation rates are positively correlated with the rate of plumage color evolution in hummingbirds

A fascinating pattern in nature is the uneven distribution of biodiversity
among clades, some with low species richness and phenotypic variation in
contrast to others with remarkable species richness and phenotypic
diversity. In animals, communication signals are crucial for intra- and
interspecific interactions, and are likely an important factor in
speciation. However, evidence for the association between the evolution of
such signals and speciation is mixed. In hummingbirds, plumage coloration
is an important communication signal, particularly for mate selection.
Here, using reflectance data for 237 hummingbird species (~66% of total
diversity), we demonstrate that color evolution rates are associated with
speciation rates, and that differences among feather patches are
consistent with an interplay between natural and sexual selection. We
found that female color evolution rates of multiple plumage elements,
including the gorget, were similar to those of males. While male color
evolution in this patch was associated with speciation, female gorget
color evolution was not. In other patches, the relationship between
speciation and color evolution rates was pervasive between sexes. We
anticipate that future studies on animal communication will likely find
that evolution of signaling traits of both sexes has played a vital role
in generating signal and species diversity.