DISSERTATION RESEARCH: The Role of Mating System in Sperm Competition and Protein Evolution in Agelaius Blackbirds

Duke University, Durham NC

Investigators

Abstract

Individual differences in the ability to compete for mates can drive evolution through a process known as sexual selection. While examples of sexual selection acting on behavior or morphology are well known, much less established is the understanding of how sexual selection acts at the molecular level to affect individual reproductive success. In species where females mate with multiple males, sperm compete for access to a female?s eggs. Sperm competition can lead to selection on seminal fluid proteins (Sfps), a class of proteins transferred by a male during mating that aid in successful fertilization by that male while reducing success of subsequent matings by other males. Because of their link to sperm competitiveness, Sfps may evolve differently in species with polygamous mating systems (with high sperm competition) compared to monogamous species (with low sperm competition). This project investigates the relationship between mating behavior and selection on Sfps in New World blackbirds (genus Agelaius), a group whose diverse behavior enables the study of how sexual selection affects DNA sequence evolution. Genes coding for Sfps will be isolated to test the hypothesis that such genes evolve faster in polygamous than in monogamous species. These genes will be archived on the NIH sequence database GenBank, providing researchers with tools for future comparative studies. Ultimately, results will clarify how selection links traits across a wide range of biological scales, from the molecular to organismal level. Mentoring and outreach efforts are integral to this project. Undergraduate students will be introduced to the basic research process by learning fundamental lab techniques and writing original papers. Results will be shared at Caribbean field sites, where a primary challenge facing natural resources agencies is reconciling the need for preservation with those of a tourist-driven economy. Work will also be communicated broadly at the university, community and national levels.