NSF Postdoctoral Fellowship in Biology FY 2021: Understanding the Demographic History of Populations using Identity-by-Descent

This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2021, Broadening Participation of Groups Under-represented in Biology. The Fellowship supports a research and training plan for the fellow that will increase the participation of groups underrepresented in biology. This project will expand the fellow’s skills in mathematics and will advance the fellow’s research on understudied population makeup in the field of genomics.

The goals of this project are to deliver insights about the historical processes that affect different types of shared genomic segments in the human genome. In particular, this work seeks to deepen knowledge of African American demographic and genetic history in the field of genomics by using mathematical and statistical models. The fellow’s work contributes to increasing the representation of diverse populations in genomics, and addressing imbalances in current genomics data sets.

The project will promote the fellow’s activities in teaching, mentoring, and working within the Stanford postdoctoral community.

This project will expand upon the fellow’s previous research, while enabling the fellow to develop skills in theoretical population genetics and stochastic simulation. The project will deliver insights about the underlying demographic processes that affect the length distribution of runs of homozygosity (ROH) and identical-by-descent (IBD) segments in the human genome, and it will provide historically relevant information about admixed populations.

First, forward-in-time simulations will be used to generate a spectrum of demographic histories to determine the expected length distribution and genomic burden of IBD and ROH. Next, the simulated models will be applied to empirical data to assess model accuracy and to assess possible demographic histories of understudied populations. Lastly, the fellow will use a mechanistic model of admixture to estimate the number of distinct genealogical ancestors from a source population that are required to generate current admixture fractions in an admixed individual.

This admixture model will be applied to African American populations to estimate the expected number of African and European individuals that contributed to the genomes of modern admixed individuals. This project will bridge the fields of anthropology, biology, and statistics by using mathematical models to understand how populations evolve over time and to understand the evolutionary forces acting on modern genomes.

In addition to academic research, the fellow will continue teaching, cultivating relationships with other underrepresented students in STEM through mentorship, and active participation in diversity efforts at Stanford.

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.