| 1. |
- Owers, Katharine A., et al.
(författare)
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Adaptation to infectious disease exposure in indigenous Southern African populations
- 2017
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : ROYAL SOC. - 0962-8452 .- 1471-2954. ; 284:1852
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Tidskriftsartikel (refereegranskat)abstract
- Genetic analyses can provide information about human evolutionary history that cannot always be gleaned from other sources. We evaluated evidence of selective pressure due to introduced infectious diseases in the genomes of two indigenous southern African San groups-the double dagger Khomani who had abundant contact with other people migrating into the region and the more isolated Ju vertical bar'hoansi. We used a dual approach to test for increased selection on immune genes compared with the rest of the genome in these groups. First, we calculated summary values of statistics that measure genomic signatures of adaptation to contrast selection signatures in immune genes and all genes. Second, we located regions of the genome with extreme values of three selection statistics and examined these regions for enrichment of immune genes. We found stronger and more abundant signals of selection in immune genes in the double dagger Khomani than in the Ju vertical bar'hoansi. We confirm this finding within each population to avoid effects of different demographic histories of the two populations. We identified eight immune genes that have potentially been targets of strong selection in the double dagger Khomani, whereas in the Juj'hoansi, no immune genes were found in the genomic regions with the strongest signals of selection. We suggest that the more abundant signatures of selection at immune genes in the double dagger Khomani could be explained by their more frequent contact with immigrant groups, which likely led to increased exposure and adaptation to introduced infectious diseases.
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| 2. |
- Schlebusch, Carina M., et al.
(författare)
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Genomic Variation in Seven Khoe-San Groups Reveals Adaptation and Complex African History
- 2012
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 338:6105, s. 374-379
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Tidskriftsartikel (refereegranskat)abstract
- The history of click-speaking Khoe-San, and African populations in general, remains poorly understood. We genotyped ∼2.3 million SNPs in 220 southern Africans and found that the Khoe-San diverged from other populations ≥100,000 years ago, but structure within the Khoe-San dated back to about 35,000 years ago. Genetic variation in various sub-Saharan populations did not localize the origin of modern humans to a single geographic region within Africa; instead, it indicated a history of admixture and stratification. We found evidence of adaptation targeting muscle function and immune response, potential adaptive introgression of UV-light protection, and selection predating modern human diversification involving skeletal and neurological development. These new findings illustrate the importance of African genomic diversity in understanding human evolutionary history.
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