This week EEB welcomes Dr. Mike Webster of Cornell University who will present:
Sexual Signals, Divergence, & Reproductive Isolation in Australian Fairy-wrens
Sexual selection is generally thought to promote divergence between populations and potentially also lead to reproductive isolation (i.e., speciation), but the behavioral mechanisms underlying this process generally are not well understood. We are exploring these mechanisms in populations of the red-backed fairy-wren, an Australian passerine bird, as well as other species of fairy-wren. Broad geographic sampling shows strong divergence across populations in male sexual signals, including both plumage coloration and song. Genomic approaches reveal a strong cline of genetic divergence separating eastern from western populations. This genetic cline is concordant with variation in songs, but differs significantly from the cline in plumage signals, indicating that plumage traits, but not song traits, are introgressing across populations. Field experiments that manipulated both signal types reveal that female mating preferences promote introgression of plumage traits, and also that male-male competition limits introgression of song but allows introgression of plumage. Together these results call for increased attention to the behavioral responses of conspecifics to divergent sexual signals, as these responses will determine the patterns of reproductive isolation that result.
Mini-bio: Mike Webster’s research focuses on the social behavior of birds from an evolutionary perspective, particularly focusing on the processes and outcomes of sexual selection. Research in Webster’s lab is integrative and examines issues from both ultimate and proximate perspectives, and combines intensive fieldwork with genetic, hormonal and other lab analyses to unlock the secret lives of birds and other taxa. Most of this work focuses on New World Warblers and Australian Fairy-wrens. Webster received his B.S. degree from the University of California at San Diego, and his Ph.D. from Cornell University. After a Postdoctoral Position at the University of Chicago, Webster moved to academic appointments at SUNY Buffalo and Washington State University. Currently, he is the Robert G. Engel Professor of Ornithology in the Department of Neurobiology and Behavior at Cornell University, and also Director of the Macaulay Library at the Cornell Lab of Ornithology.
The EEB Seminars run weekly, on Thursdays, in the EEB Lounge of the BioSciences Complex, Room 4338, from 12:30-1:30pm. Light refreshments are served starting at 12:15.