Melanin coloration in New World orioles II: ancestral state reconstruction reveals lability in the use of carotenoids and phaeomelanins.

摘要

Although many animals use carotenoids to produce bright yellow, orange, and red colors, an increasing number of studies have found that other pigments, such as melanins, may also be used to produce bright colors. Yet, almost nothing is known about the evolutionary history of this colorful melanin use. We used reflectance spectrometry to determine whether colors in New World orioles were predominantly due to carotenoids, colorful melanins, or a mixture of both. We then used ancestral state reconstruction to infer the directionality of any pigment changes and to test for phylogenetic signal. We found that three oriole taxa likely switched from carotenoid- to melanin-based colors. Several other oriole taxa apparently gained localized melanin coloration, or had coloration that seemed to be produced by a mixture of carotenoids and melanins. We also found little phylogenetic signal on the use of carotenoids or melanins to produce color. However, all pigment changes occurred within one of three major clades of the oriole genus, suggesting there may be signal at deeper phylogenetic levels. These repeated independent switches between carotenoid and melanin colors are surprising in light of the important signaling role that color pigments (especially carotenoids) are thought to play across a wide range of taxa.