Meeting Abstract

85.3  Tuesday, Jan. 6  The evolution of carotenoid pigment systems: a biochemical and phylogenetic approach HILL, G. E. *; MCGRAW, K. J.; LIGON, R. A.; Auburn Univ., Auburn; Arizona State Univ., Tempe; Auburn Univ., Auburn ghill@auburn.edu

More elaborate or costly sexually selected traits are commonly thought to evolve from less exaggerated or expensive character states, but rarely can we trace evolutionary patterns of sexual signaling at a mechanistic level to uncover the true trajectories of trait evolution. Carotenoid-based colors in birds offer the unique opportunity to investigate the phylogenetic history of sexual ornaments because we can determine the types of carotenoid molecules that are deposited into the integument. Some species acquire their bright plumage using basic dietary carotenoids while others deposit more costly, metabolically derived pigments in feathers. We used published phylogenies and data on the carotenoid content of feathers to examine the evolution of pigment systems across a genus-level phylogeny of cardueline finches and a family-level phylogeny of oscine passerines. Outgroup and basal members for both cardueline finches and a subgroup of oscine passerines used only dietary carotenoids to color their feathers yellow; metabolically derived yellow and red feather colorants appeared later in more derived taxa. These results demonstrate a pattern of directional color evolution and provide biochemical support for the prediction that more costly animal signals evolve from those that are comparatively easier to develop.