Recombination is responsible for the generation and shuffling of variation in the genome of most organisms. Therefore, understanding how certain historical events influence recombination patterns is a fundamental question for studying primate diversity in general and human diversity in particular. DNA sequence data is informative about how processes like historical adaptation or changes in population size and growth generate different patterns of recombination in the genome. Some research shows that recombination rates can vary dramatically across the genome, even in the same genomic regions between humans and chimpanzees. Therefore, recombination rates may change over very short periods of time, which can have implications for how genetic variation accumulates and leads to differentiation within and between humans over time. In this respect, a sampling of more closely related primates is needed to address how rapid these recombination rate patterns change given that the divergence time of 5-7 MY between humans and chimpanzees may be too distant. In addition, most of the previous data have come from studies of gene regions or collections of disease markers or from samples of chimpanzee individuals from the same family. These samples of gene regions and related individuals are biased and may have largely influenced our general understanding of how recombination rates vary over random regions of the human genome.
To address these issues, this project will sample 20 genome regions (each of ~15,000 nucleotides in size), which do not have protein-coding genes, in population samples of unrelated western chimpanzees (Pan troglodytes verus) and bonobos (Pan paniscus), which are estimated to have diverged ~0.9-1.8 million years (MY) ago. Analyses of population structure, correlations among DNA mutations, and patterns of natural selection, between the genomes of these closely related primates will enable the testing of hypotheses about how recombination patterns change over short periods of time in the human genome.
