BRC-BIO: Proximate and ultimate explanations of extra-pair reproduction in a house wren population

Board Of Trustees Of Illinois State University, Normal IL

Investigators

Abstract

Animals face a multitude of choices throughout their lives. One of the most consequential decisions is which of many potential mates they should choose for reproduction. Birds in species that typically form male-female social pairs for mating and joint care of their offspring also frequently mate outside of the social pair bond with nearby birds. The possible costs and benefits of such extra-pair reproduction are not well understood, nor is it clear how exactly animals choose these mates. Genetic and behavioral data will be collected in a well-studied wild population of house wrens (Troglodytes aedon) to test whether females choose to mate outside of their pair bond with neighboring males that will provide them with better genes for their offspring than their social mate. This project will further investigate whether females base their choice on certain male song characteristics and how females and other males react to more- and less-attractive songs. In addition to addressing topics of fundamental interest in biology, this research will lead to the development of critical but rare genomic information for a wild population with extraordinary long-term records and fitness data. An important focus of this project will be to provide training opportunities and research experiences for undergraduate and graduate students and to introduce high school students and the young and adult public to the process of scientific research. These initiatives will contribute to recruitment and retention of underrepresented groups in science and will improve the scientific literacy of the public. Males of socially monogamous species gain obvious fitness benefits through extra-pair reproduction, but the benefits are less obvious for females. Several possible explanations of female extra-pair reproduction can only be tested with detailed genetic pedigree records or genomic data that are still rarely available for wild populations with fitness records. Additionally, it is unclear how females choose which males to mate with outside of the pair bond. Many birds sing to attract mates and defend territories, but it is unclear which song characteristics determine the attractiveness of song to females because individual song components are often studied in isolation, rather than simultaneously as multi-component traits. This research will test if good-genes benefits provide an ultimate explanation for female extra-pair reproduction. The genetic data will also lay the foundation for testing additional explanations and many other questions in the future. Next, it will be investigated whether song serves as a proximate signal that females use to choose their extra-pair mates. This research will determine what makes songs of potential extra-pair mates attractive to females and then synthesize songs predicted to be attractive or unattractive according to a multivariate selection analysis. Playback experiments will verify the attractiveness of these songs to females and test how males react to attractive or unattractive song to identify suspected trade-offs between song characteristics that are attractive to females and song characteristics that elicit aggressive responses from male rivals. 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.