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Nat Ecol Evol. 2018 Apr;2(4):721-730. doi: 10.1038/s41559-018-0496-4. Epub 2018 Mar 12.

The demographic history and mutational load of African hunter-gatherers and farmers.

Author information

1
Unit of Human Evolutionary Genetics, Institut Pasteur, Paris, France.
2
Centre National de la Recherche Scientifique UMR 2000, Paris, France.
3
Center of Bioinformatics, Biostatistics and Integrative Biology, Institut Pasteur, Paris, France.
4
Unit of Human Evolutionary Genetics, Institut Pasteur, Paris, France. kousathanas2@gmail.com.
5
Centre National de la Recherche Scientifique UMR 2000, Paris, France. kousathanas2@gmail.com.
6
Center of Bioinformatics, Biostatistics and Integrative Biology, Institut Pasteur, Paris, France. kousathanas2@gmail.com.
7
Laboratoire de Langue, Culture et Cognition, Université Omar Bongo, Libreville, Gabon.
8
Centre National de la Recherche Scientifique UMR 5596, Dynamique du Langage, Université Lumière-Lyon 2, Lyon, France.
9
Institut de Recherche pour le Développement UMR 208, Muséum National d'Histoire Naturelle, Paris, France.
10
Departments of Anthropology and Biology, Pennsylvania State University, University Park, PA, USA.
11
Université de Montréal, Centre de Recherche du Centre Hospitalier Universitaire Sainte-Justine, Montréal, Canada.
12
Centre National de la Recherche Scientifique UMR 7206, Muséum National d'Histoire Naturelle, Université Paris Diderot, Sorbonne Paris Cité, Paris, France.
13
Unit of Human Evolutionary Genetics, Institut Pasteur, Paris, France. quintana@pasteur.fr.
14
Centre National de la Recherche Scientifique UMR 2000, Paris, France. quintana@pasteur.fr.
15
Center of Bioinformatics, Biostatistics and Integrative Biology, Institut Pasteur, Paris, France. quintana@pasteur.fr.

Abstract

Understanding how deleterious genetic variation is distributed across human populations is of key importance in evolutionary biology and medical genetics. However, the impact of population size changes and gene flow on the corresponding mutational load remains a controversial topic. Here, we report high-coverage exomes from 300 rainforest hunter-gatherers and farmers of central Africa, whose distinct subsistence strategies are expected to have impacted their demographic pasts. Detailed demographic inference indicates that hunter-gatherers and farmers recently experienced population collapses and expansions, respectively, accompanied by increased gene flow. We show that the distribution of deleterious alleles across these populations is compatible with a similar efficacy of selection to remove deleterious variants with additive effects, and predict with simulations that their present-day additive mutation load is almost identical. For recessive mutations, although an increased load is predicted for hunter-gatherers, this increase has probably been partially counteracted by strong gene flow from expanding farmers. Collectively, our predicted and empirical observations suggest that the impact of the recent population decline of African hunter-gatherers on their mutation load has been modest and more restrained than would be expected under a fully recessive model of dominance.

PMID:
29531345
DOI:
10.1038/s41559-018-0496-4
[Indexed for MEDLINE]

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