CAREER: Carotenoid coloration in an evolutionary radiation: Connecting molecular function, fitness, and diet ecology in wood warblers

What are the genes that define the differences among closely related species, and how do differences at these genes translate to distinct traits? How do these traits influence the success of individuals in producing more offspring (i.e. increasing fitness)? These questions are fundamental to our understanding of biological diversity but remain poorly understood. This project aims to explicitly link genes, traits, and fitness in a group of colorful songbirds, called wood warblers. The researchers have previously identified candidate genes responsible for differences in coloration in the group, particularly those involving carotenoid molecules. This project will test how those genetic differences actually translate into differences in the enzymes that interact with carotenoid molecules. The project will also include a field study of birds that differ in their carotenoid coloration to study how different coloration traits influence reproduction. In addition, given that carotenoids must be obtained from the diet—i.e. birds cannot synthesize them on their own—the project includes undergraduate researchers using molecular tools to test hypotheses about the diet of birds from fecal samples. Finally, to help broaden participation in science, inspire students, and entice them to learn more about the natural world, the project will develop a set of virtually immersive evolutionary biology experiences focused on avian ecology and evolution.The research project focuses on wood warblers (Parulidae), a family of birds with over 100 species that diversified within the last 10 million years, and which has one of the fastest diversification rates across songbirds. The goal of the project is to study the evolutionary history of genes—and their function—potentially involved in the diversification of this group. The focus of the current study is on carotenoid processing genes, specifically beta carotene oxygenase 2 (BCO2). This gene has been implicated in plumage coloration in these and other birds, yet it has not been functionally characterized outside of domesticated species. The goal will be to characterize the carotenoids present across the radiation of warblers, and also synthesize the multiple BCO2 protein variants and test how they interact in vitro with different carotenoid substrates. The work includes a field study of hybridizing Vermivora warblers, which differ in their BCO2 genotypes, to test whether these have an influence on phenotypes. This will require a multi-generational pedigree of individuals within the hybrid zone. Recognizing the dietary dependence of carotenoids, the project engages undergraduate researchers in using molecular tools to analyze fecal samples from these birds in the hybrid zone. This allows for testing hypotheses about the birds' diets, shedding light on the intricate relationship between gene expression, traits, and other ecological factors. Finally, the work includes a partnership with Penn State’s Center for Immersive Experiences to generate a set of virtual reality experiences and 360-degree videos that will give high-school and undergraduate students in central Pennsylvania a sense of the type of field work, as well as teach them about the biology and genetics of hybridization.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.