Evolution

Origins of Variation

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Science  02 Nov 2012:
Vol. 338, Issue 6107, pp. 582
DOI: 10.1126/science.338.6107.582-c

It is not clear whether the majority of selection on human genetic variation originates from de novo mutations (SDN) or from selection on previously neutral, or nearly neutral, standing genetic variation (SSV). Peter et al. examined theoretical models to determine parameters that distinguish between SDN and SSV. Identifying the origin of the genetic variant was dependent on the strength of selection and the frequency of the variant under selection. Examining genes previously identified to be under selection, but not yet fixed within humans, revealed that both models were applicable; save for the gene that encodes glucose-6-phosphate dehydrogenase, which appears to be under balancing selection and, because of the lack of a selective sweep, did not fit either model. Furthermore, when regions currently not under selection were examined, it was not possible to discriminate between selected and neutral variants. These results support the notion that the origin of human genetic variation that is subject to selection is complex and that an understanding of both standing variation and the de novo mutation rate is important to trace our evolution.

PLoS Genet. 8, 10.1371/journal.pgen.1003011 (2012).

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