NSF Postdoctoral Fellowship in Biology FY 2020: Bridging genomics, physiology, and behavioral ecology to uncover mechanisms driving incipient speciation in an island bird

Shogren, Elsie H, Manhattan KS

Investigators

Abstract

This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2020, Integrative Research Investigating the Rules of Life Governing Interactions Between Genomes, Environment and Phenotypes. The fellowship supports research and training of the fellow that will contribute to the area of Rules of Life in innovative ways. Combining studies of behavior and physiology with genomic data, the research will enhance understanding about new species arising in isolated habitats. The project focuses on a group of birds, Monarcha flycatchers, found only in the Solomon Islands in the South Pacific. On the smaller islands of the archipelago, previous research uncovered repeated evolution of all black (melanic) coloration from chestnut colored ancestors. In most populations where this occurred, all birds are now melanic and mate only with other melanic individuals, resulting in a new species. The reasons for color differences across islands are unknown. To determine what is underlying the evolution of black coloration, the fellow will study an island population in which both melanic and chestnut colored birds still exist and mate with each other. This will provide insight into processes that drive evolution of novel traits and the origin of species. Knowing how behavior, physiology, and genetics interact to influence species evolution will facilitate appreciation and preservation of the world’s remarkable biodiversity. To broaden the impact of the project, a case study will be designed for high school students about how species evolve. Understanding how and why visual signals change in the context of incipient speciation is crucial to discerning drivers of population divergence. In a population polymorphic for two distinct visual signals – melanic and chestnut coloration – this project tests three alternative hypotheses explaining repeated evolution of melanism in the Monarcha clade. Melanism may be under indirect selection due to pleiotropic effects of the melanocortin system, and associations with testosterone and/or aggression. Alternatively, interaction and competition with conspecifics may drive social selection for melanism. Finally, melanism may arise through genetic drift via small populations and minimal negative pleiotropy. Testing predictions of these hypotheses involves three aims: (1) determine effects of plumage color on aggressive behavior through mount presentation experiments; (2) characterize the evolutionary processes mediating and genetic architecture underlying melanism using whole-genome resequencing data; and (3) measure alpha-Melanocyte Stimulating Hormone and testosterone in melanic, chestnut, and plumage-manipulated birds. The fellow will benefit from in-depth experience integrating whole-genome analyses with phenotypic, behavioral, and physiological responses. In addition, this study will be featured in a case study designed to educate high school students about speciation, convergent evolution, and the scientific process. 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.