Doctoral Dissertation Improvement: Population genomics of a baboon hybrid zone in Zambia

Washington University, Saint Louis MO

Investigators

Abstract

Hybridization, defined as interbreeding between genetically distinct populations, is increasingly recognized as a common occurrence in plants and animals that is important for understanding the speciation process. While most speciation probably results from physical barriers to genetic interchange, this separation is not always absolute and the possibility of hybridization is ever-present. In primates, ongoing hybridization has been identified in most major taxonomic groups and recent studies are increasingly detecting episodes of ancient hybridization in the genomes of living primates, including humans. The mechanisms of hybridization and its role in shaping primate evolutionary histories, however, remain unresolved. This research by doctoral student Kenneth Chiou (Washington University in St. Louis), under the supervision of Dr. Jane Phillips-Conroy, uses hybridization as a 'natural experiment' for understanding the spatial structure of genetic variation in Kinda and gray-footed chacma baboons, which hybridize in and around Kafue National Park, Zambia. Like humans, baboons inhabit diverse environments, have long life histories and complex social organizations, and share a recent common ancestor, making them ideal models for understanding global patterns of genetic variation in humans. Using the latest DNA sequencing techniques, tens of thousands of markers from across the nuclear and mitochondrial genomes are typed from individuals across the hybrid zone. These markers are used to better understand the roles of local adaptation and of differences in social organization in structuring genetic variation within species, between species, and in interspecific hybrids. This study provides an innovative framework for characterizing the influences of various processes on genetic variation. As one of the first genomic studies of a wild primate hybrid zone, this study increases our understanding of natural hybridization and generates the first genetic data for large areas of a major baboon contact zone. DNA sequence data are deposited in public databases and all software is made freely available under open source licenses. By creating opportunities for collaboration and outreach in both the United States and abroad, this project helps promote scientific literacy and the maintenance of biodiversity.