DISSERTATION RESEARCH: Sources of Selection on a Complex Signal in Sparrows

Duke University, Durham NC

Investigators

Abstract

Animals use signals to identify potential mates of their own species, and also to assess the quality of potential mates. Thus, the processes by which individuals choose mates may play a role in speciation. Bird song is an important model system for studying the production, perception, development, and function of animal signals, including human speech. The proposed research aims to identify how the production, perception and function of bird song influence the way bird song changes over time. An interesting pattern of change in the trilled portion of songs over a 30-year period was demonstrated recently in five different populations of white-crowned sparrows (Zonotrichia leucophrys). This pattern suggests that trills may be changing due to selection by female choice or through correlated change with morphology or with habitat structure. The proposed research uses experiments and observations to test the relative importance of female choice, morphological change, and habitat change in explaining patterns of trill evolution. This study is the first to assess in a single species whether these multiple forces influence changes in song over time and the potential balance between selection and constraints on song in multiple populations. The intellectual merit of this project is to increase understanding of how and why animal signals change over time and more generally to increase scientific understanding of processes driving speciation. Broader impacts: This project will support the training of one female graduate student and increase her chances of achieving her professional goals as a woman in science. Preliminary work on this project has already additionally contributed to the research education of several undergraduate women in science, including those from under represented groups. This project also will support collaboration between Duke University and the Point Reyes Bird Observatory (PRBO). Part of this collaboration will include an exchange of knowledge on long-term trends in white-crowned sparrow breeding habitat and song behavior, which can play a valuable role in understanding the factors that affect the viability of songbird populations and thus contribute to their conservation in the future. Finally, work on this project will lead to long-term preservation and availability of an important set of field audio recordings of white-crowned sparrow populations over a 30-year period and currently archived at the California Academy of Science.