NSF Postdoctoral Fellowship in Biology FY 2019

Beckman, Elizabeth Jane, Richmond CA

Investigators

Abstract

This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2019, Research Using Biological Collections. The fellowship supports research and training of the fellow that will utilize biological collections in innovative ways. When hybridization occurs (the exchange of genetic information) between two species, genetic variants (known as alleles) that originated in one species may be introduced into another species. Evidence from DNA sequencing in vertebrates so far suggests that most introduced alleles are removed by natural selection. However, sometimes introduced alleles are beneficial and impact important traits like pesticide-resistance and coat color. Understanding the role of natural selection to eliminate or promote introduced alleles is essential to learning how wild populations adapt to their environments, but this has not been well studied. In this project, the fellow will identify introduced alleles and genes related to environmental adaptation in two closely-related bird species that hybridized historically. If alleles related to environmental adaptation in one species are found in the other, this will reveal a positive role for selection on introduced alleles. By using new sequencing techniques, working with undergraduates and creating an online educational lesson, the fellow will develop skills required to succeed as a researcher and teacher. To examine the dual role of natural selection on introduced alleles, the fellow will characterize selection and introgression in two species with different colonization histories to high elevation. The lack of environmental oxygen (hypoxia) at high elevation presents a chronic selective pressure on residents with high metabolic rates like birds, and many species that occupy high elevation possess derived genetic adaptations. The fellow previously documented genome-wide introgression between the Bolivian Hooded siskin, a recent colonist to high elevation, and the Black siskin, a high elevation specialist, as well as directional introgression of two high-elevation associated loci. With this framework, the fellow will test for evidence of adaptive introgression genome-wide in the Bolivian Hooded siskin. To examine if natural selection has favored the introgression of high-elevation adapted alleles into the Bolivian Hooded siskin, the fellow will (1) test if a disproportionate number of alleles with Black-siskin ancestry in the Bolivian Hooded siskin are in genes associated with hypoxia adaptation, and (2) if these hypoxia-related genes from the Black siskin bear a signature of positive selection in the Bolivian Hooded siskin. This study will demonstrate if adaptive introgression has played a critical role in the persistence of the Bolivian Hooded siskin at high elevation. 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.