RAPID PHENOTYPIC EVOLUTION THROUGH THE RESHUFFLING OF PIGMENTATION GENES

Speciation, or the origin of new species, is generally a slow process, originating from long periods of geographic isolation and the eventual accumulation of mutations. Rapid radiations, in which many species accumulate in a short period of time, represent rare opportunities to study the genetic and ecological contexts that lead to evolution and speciation. One possible mechanism for rapid evolution is through mixing and reassembling old genetic variants, which may already exist in other species, into novel combinations. Hybridization may provide the source for the rapid generation of new genetic combinations. This process can lead to the rapid evolution of novel traits, like coloration patterns, without the long period required for new relevant mutations to arise. Coloration is central to animal communication, mediating key behaviors like mate choice, which over time can kickstart the speciation process. This research will focus on a group of South American birds, the capuchino seedeaters (genus Sporophila). These birds are remarkably similar genetically yet are primarily differentiated at variants near genes involved in feather pigment deposition. This project will combine expertise from evolutionary biologists and materials scientists to understand how plumage coloration evolves and fuels rapid evolution. The proposed research will lead to a better understanding of the chemical, structural, and genetic mechanisms behind color production. It will also explore how these changes contribute to speciation. The project will enable student training opportunities and the results from this research will be communicated to a broad audience through popular web platforms. This research will first consist of a detailed study of the mechanisms behind color production in feathers, including the pigment composition and the nano- and micro-structural properties of feathers of different colors. This detailed understanding of coloration phenotypes will be combined with gene expression data from growing feather follicles sampled at comparable developmental times. Finally, the results from previous population genomic studies on these taxa and the new transcriptional data will be used to build a mechanistic and evolutionary model for how color diversity and patterning are generated. The broader impacts of this project include an interactive multimedia-based module on the mechanisms behind avian plumage coloration hosted by the Cornell Lab of Ornithology (~10 million views per year). The project will also be used as a platform to host a workshop for students who seek to apply genomic techniques to answer their own research questions. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.