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mtDNA selection

Wednesday 28 September 2005

Human mtDNA shows striking regional variation, traditionally attributed to genetic drift. However, it is not easy to account for the fact that only two mtDNA lineages (Haplogroup M and Haplogroup N) left Africa to colonize Eurasia and that Haplogroup A, Haplogroup C, Haplogroup D, and Haplogroup G show a 5-fold enrichment from central Asia to Siberia. As an alternative to drift, natural selection might have enriched for certain mtDNA lineages as people migrated north into colder climates.

- ATP6 gene had the highest amino acid sequence variation of any human mtDNA gene, even though ATP6 is one of the more conserved mtDNA proteins.

  • Comparison of the kaks ratios for each mtDNA gene from the tropical, temperate, and arctic zones revealed that ATP6 was highly variable in the mtDNAs from the arctic zone, cytochrome b was particularly variable in the temperate zone, and cytochrome oxidase I was notably more variable in the tropics.
  • Multiple amino acid changes found in ATP6, cytochrome b, and cytochrome oxidase I appeared to be functionally significant.
  • Selection may have played a role in shaping human regional mtDNA variation and that one of the selective influences was climate.

References

- Mishmar D, Ruiz-Pesini E, Golik P, Macaulay V, Clark AG, Hosseini S, Brandon M, Easley K, Chen E, Brown MD, Sukernik RI, Olckers A, Wallace DC. Natural selection shaped regional mtDNA variation in humans. Proc Natl Acad Sci U S A. 2003 Jan 7;100(1):171-6. PMID: 12509511