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Genome Biol Evol. 2015 Nov 26;7(12):3484-95. doi: 10.1093/gbe/evv236.

Extensive Admixture and Selective Pressure Across the Sahel Belt.

Author information

1
Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal Instituto de Patologia e Imunologia Molecular da Universidade do Porto (IPATIMUP), Porto, Portugal Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto (ICBAS), Porto, Portugal.
2
Instituto de Patologia e Imunologia Molecular da Universidade do Porto (IPATIMUP), Porto, Portugal Department of Biology, CBMA (Centre of Molecular and Environmental Biology), University of Minho, Braga, Portugal.
3
Unit of Human Evolutionary Genetics, Institut Pasteur, Paris, France Centre National de la Recherche Scientifique, Paris, France.
4
Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal Instituto de Patologia e Imunologia Molecular da Universidade do Porto (IPATIMUP), Porto, Portugal.
5
Archaeogenetics Laboratory, Institute of Archaeology of the Academy of Sciences of the Czech Republic, Prague, Czech Republic.
6
Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal Instituto de Patologia e Imunologia Molecular da Universidade do Porto (IPATIMUP), Porto, Portugal Faculdade de Medicina da Universidade do Porto, Porto, Portugal lpereira@ipatimup.pt.

Abstract

Genome-wide studies of African populations have the potential to reveal powerful insights into the evolution of our species, as these diverse populations have been exposed to intense selective pressures imposed by infectious diseases, diet, and environmental factors. Within Africa, the Sahel Belt extensively overlaps the geographical center of several endemic infections such as malaria, trypanosomiasis, meningitis, and hemorrhagic fevers. We screened 2.5 million single nucleotide polymorphisms in 161 individuals from 13 Sahelian populations, which together with published data cover Western, Central, and Eastern Sahel, and include both nomadic and sedentary groups. We confirmed the role of this Belt as a main corridor for human migrations across the continent. Strong admixture was observed in both Central and Eastern Sahelian populations, with North Africans and Near Eastern/Arabians, respectively, but it was inexistent in Western Sahelian populations. Genome-wide local ancestry inference in admixed Sahelian populations revealed several candidate regions that were significantly enriched for non-autochthonous haplotypes, and many showed to be under positive selection. The DARC gene region in Arabs and Nubians was enriched for African ancestry, whereas the RAB3GAP1/LCT/MCM6 region in Oromo, the TAS2R gene family in Fulani, and the ALMS1/NAT8 in Turkana and Samburu were enriched for non-African ancestry. Signals of positive selection varied in terms of geographic amplitude. Some genomic regions were selected across the Belt, the most striking example being the malaria-related DARC gene. Others were Western-specific (oxytocin, calcium, and heart pathways), Eastern-specific (lipid pathways), or even population-restricted (TAS2R genes in Fulani, which may reflect sexual selection).

KEYWORDS:

Sahel; admixture; genome-wide diversity; selection

PMID:
26614524
PMCID:
PMC4700964
DOI:
10.1093/gbe/evv236
[Indexed for MEDLINE]
Free PMC Article

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