title: Selection, constraint, and the evolution of coloration in African starlings.
abstract: Colorful plumage plays a prominent role in the evolution of birds, influencing communication (sexual/social selection), and crypsis (natural selection). Comparative studies have focused primarily on these selective pressures, but the mechanisms underlying color production can also be important by constraining the color gamut upon which selection acts. Iridescence is particularly interesting to study the interaction between selection and color-producing mechanisms because a broad range of colors can be produced with a shared template, and innovations to this template further expand this by increasing the parameters interacting to produce colors. We examine the patterns of ornamentation and dichromatism evolution in African starlings, a group remarkably diverse in color production mechanisms, social systems, and ecologies. We find that the presence of iridescence is ancestral to the group, being predominantly lost in females and cooperative breeders, as well as species with less labile templates. Color-producing mechanisms interact and are the main predictors of plumage ornamentation and elaboration, with little influence of selective pressures in their evolution. Dichromatism, however is influenced by social system and the loss of iridescence. Our results show the importance of considering both selection and constraints, and the different roles that they may have, in the evolution of ornamentation and dimorphism.
authors.affiliation: Department of Biology, Integrated Bioscience Program, University of Akron, Akron, Ohio, 44325. rm3368@columbia.edu.|Department of Ecology, Evolution, and Environmental Biology, Columbia University, New York, New York, 10027. rm3368@columbia.edu.
authors.forename: Rafael
authors.initials: R
authors.lastname: Maia
authors.affiliation: Department of Ecology, Evolution, and Environmental Biology, Columbia University, New York, New York, 10027.|Center for Integrative Animal Behavior, Columbia University, New York, New York, 10027.
authors.forename: Dustin R
authors.initials: DR
authors.lastname: Rubenstein
authors.affiliation: Department of Biology, Integrated Bioscience Program, University of Akron, Akron, Ohio, 44325.|Department of Biology, Terrestrial Ecology Unit, University of Ghent, Ledeganckstraat 35 9000 Ghent, Belgium.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Shawkey
mesh_terms: D000818:Animals; D019143:Evolution, Molecular; D005260:Female; D008297:Male; D010858:Pigmentation / Q000235:genetics*; D012641:Selection, Genetic; D046749:Starlings / Q000235:genetics*
keywords: Cooperative breeding; iridescence; melanosome; social selection; sociality