CAREER: Using Multiple Nuclear Introns to Reconstruct the History of Plumage Dichromatism in Orioles (Icterus).

University Of Maryland Baltimore County, Baltimore MD

Investigators

Abstract

Recent advances including the use of DNA sequencing in systematics have made Darwin's vision of a Tree of Life, showing evolutionary relationships among all organisms, a feasible goal. However, there are still challenges that must be addressed before this vision can become reality. One of the main challenges is that virtually all current molecular phylogenies (evolutionary trees) for closely related animals are based on maternally inherited mitochondrial DNA sequences. Mitochondrial DNA works well for many reasons, but independent nuclear sequences are needed to test these mitochondrial trees where they are controversial. The published mitochondrial tree for orioles is one of the most controversial in all of bird systematics, so it is an ideal phylogeny to test using nuclear sequences. Five different nuclear intron regions will be sequenced to evaluate the oriole evolutionary tree. Nuclear introns are free to mutate more rapidly than protein coding gene regions, so they are good candidate regions for rapidly evolving sequences in the nuclear genome. The resulting evolutionary tree will be used to infer the history of plumage color differences (dimorphism between the sexes) in orioles. In some groups of animals, changes in female color may be the main cause of gains and losses of dimorphism. In orioles and many other groups of birds, females in temperate migratory species are generally dull colored, whereas females in tropical non-migratory species are generally elaborately colored. These orioles therefore present an excellent opportunity to reconstruct changes in plumage color dimorphism, and investigate the possible causes of changes in female plumage brightness. In addition, this project will test and demonstrate the value of combining data from introns, mitochondrial DNA and morphology. Combining multiple nuclear intron sequences may provide a basis for constructing whole genome trees for all closely related animal species. This research program by Prof. Kevin Omland at University of Maryland Baltimore County provides many opportunities for education and outreach activities. The project includes an international student exchange program between the University of Maryland Baltimore County (UMBC) and the National Autonomous University of Mexico (UNAM). Over the last six years, Prof. Omland has been developing a research and undergraduate exchange program with researchers at UNAM. This exchange model will be expanded to include UMBC students, especially from UMBC's well-known minority science programs, who will assist with field and museum research in Mexico. Undergraduate students from Maryland and Mexico will have the opportunity to travel internationally and participate in a wide range of systematics research. The research team will produce a bilingual website on orioles to help disseminate findings to both English and Spanish speakers, and to promote understanding of evolution, systematics and biodiversity. In the classroom at UMBC the oriole research program will be used as an extended case study in active learning exercises to help illuminate the process of science. The Baltimore Oriole is the state bird and the mascot of the local baseball team, which helps make this research accessible to students and the public. This international research and exchange program will foster US-Mexico collaboration, and promote systematics research to a diverse audience.