Genomic signatures of reproductive isolation in a primate hybrid system

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

This project will study two closely-related species of howler monkey in order to improve our understanding of the genetics of speciation in a primate model. When two closely-related species reproduce with one another, they produce hybrid individuals that have a mixture of genetic characteristics of both species. However, there are likely to be certain genetic regions in those hybrids that are not randomly mixed and that may play be important for local adaptation, reproductive isolation, and speciation. Studying genetic mechanisms that underlie reproductive isolation in a primate hybrid system can serve as a living model to understand the mechanisms involved in shaping our own genome, in the face of recent evidence of the occurrence of hybridization between modern and archaic human populations during hominin evolution. This project will also increase diversity in science by supporting the researchers and students who are underrepresented minorities and by promoting the conservation of natural populations of primates through educational activities for school-age children in local communities. Studies of patterns of introgression (the movement of alleles from one gene pool to another through hybridization) provide an outstanding opportunity to improve our understanding of the number, distribution and function of differentiated genomic regions during the process of speciation. To explore the genetic mechanisms that underlie reproductive isolation in primates, the proposed work will analyze pure and admixed populations of two species of howler monkeys that hybridize in Mexico. Analyses of genome-wide data will be used to first determine the number and distribution of genomic regions that have higher than expected levels of divergence between non-hybridizing populations of parental species. In addition, genomic cline analyses will be performed to determine whether or not these divergent loci in allopatric populations also show reduced levels of introgression in the hybrid zone (as expected for loci involved in reproductive isolation). Levels of linkage disequilibrium will be estimated for loci with reduced introgression and the loci will be mapped to publicly available reference genomes to determine whether they are clumped or scattered throughout the genome. Sequences will also be annotated through comparison with the NCBI non-redundant protein and nucleotide databases to determine the association of these regions to genic regions with known functions and/or to regulatory regions. Finally, the proportion of non-introgressing loci located in the X chromosome relative to loci located in autosomal regions will be estimated to test the hypothesis that loci involved in reproductive isolation have accumulated in the X chromosome.