Athletic endurance is a unique trait in humans among the living primates. It has been suggested that the ability to run long distances was a key evolutionary adaptation leading to the origin of the genus Homo. It is also likely that this ability played a role during the rapid migration out of Africa. Many gene polymorphisms have been identified that underlie differences in athletic ability among humans; thus, endurance can be considered a complex trait. In this dissertation, I studied athletic endurance in humans from three different perspectives. First, I looked at a suite of 18 polymorphisms related to athletic ability in different populations across the world. I found that there is a very strong correlation between a population's endurance allele frequency and their migration distance from Africa. I also found that those endurance alleles that have increased most in frequency out of Africa show long extended haplotype homozygosity relative to other polymorphisms in the regions surrounding them. From this, I concluded that these genes underwent a soft selective sweep from standing variation during the migration out of Africa. Second, I looked for potential interactions among genes in determining athletic ability. I looked at 37 polymorphisms related to health and athleticism in endurance athletes, sprint athletes, and controls. I adapted and combined available methods to look specifically for those gene interactions that were epistatic rather than additive. While I did not find any significant results, I did find a set of suggestive interactions that point towards the involvement of the production and regulation of reactive oxygen species in distinguishing endurance athletes from power athletes. I also demonstrated that the basic application of currently-available methods for detecting gene interaction is not sufficient for distinguishing true epistasis from additive interactions. Finally, I studied a single gene for athletic endurance in depth. I looked at the full sequence of the ACTN3 gene, which has an inactivating mutation that has been associated with endurance ability, in Africans, Europeans, and Asians. I found evidence for ancient selection (80,000-250,000 years ago) on this gene, but no evidence for recent selective sweeps that had previously been reported.
|Advisor:||Ruvolo, Maryellen, Hartl, Dan|
|School Location:||United States -- Massachusetts|
|Source:||DAI-B 72/09, Dissertation Abstracts International|
|Subjects:||Molecular biology, Genetics, Evolution and Development|
|Keywords:||Alpha-actinin-3, Athletic endurance, Epistasis, Molecular evolution, Soft sweep|
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