Comparative population genetics of the Hominoidea: An investigation of locus-specific and genome-wide influences
AuthorAltheide, Tasha Kay
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PublisherThe University of Arizona.
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AbstractOne of the central questions in population genetics is how different forces of evolution influence patterns of genetic variation within and between species. Locus-specific forces of natural selection, like selective sweeps and background selection, are expected to influence only the target of selection and any sites linked to that target. In contrast, genome-wide forces are expected to influence mane different loci simultaneously. In particular, genome-wide forces that have a sex-specific component are predicted to exert disparate influence over the four different genomic compartment, (mitochondrial DNA, non-recombining portion of the Y chromosome (NRY), X chromosome, autosomes) depending on their degree of maternal or paternal inheritance. This study compared levels of genetic variation across the four genomic compartments in the Hominoidea (humans, chimpanzees, bonobos, gorillas, and orangutans) in order to test the hypothesis that a high variance in male reproductive success, as predicted from behavioral data, may influence levels of hominoid genetic diversity. First, comparative chromosome and mitochondria) DNA diversity was quantified across species. NRY diversity was lower than mitochondria) DNA diversity in all taxa, and gorillas exhibited no NRY genetic diversity, consistent with their polygynous mating system. In order to determine whether locus-specific or genome-wide factors were responsible, diversity from all four genomic compartments was compared across species. The multilocus approach revealed patterns of variation across all hominoids that are consistent with a model of high variance in male reproductive success: relatively high mitochondrial DNA diversity, relatively low Y chromosome diversity, and intermediate X and autosomal diversity. Examination of orangutan population structure for NRY, mitochondrial DNA, and X-linked loci suggested an influence of sex-specific demographic influence, but was unclear whether other factors were involved. The study suggests that there is an influence of a high variance in male reproductive success on the hominoid genome, but does not preclude the influence of additional locus-specific factors. There are potentially important implications for population genetic models that assume a sex ratio of 1. Additional loci and additional species need to be examined to determine the generality of the pattern, as well as to further investigate the interplay between genome-wide and locus-specific factors.
Degree ProgramGraduate College
Ecology and Evolutionary Biology