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

Marie Lopez, Athanasios Kousathanas, Hélène Quach, Christine Harmant, Patrick Mouguiama-Daouda, Jean Marie Hombert, Alain Froment, George H. Perry, Luis B. Barreiro, Paul Verdu, Etienne Patin, Lluís Quintana-Murci

Research output: Contribution to journalReview article

15 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)721-730
Number of pages10
JournalNature Ecology and Evolution
Volume2
Issue number4
DOIs
StatePublished - Apr 1 2018

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics
  • Ecology

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    Lopez, M., Kousathanas, A., Quach, H., Harmant, C., Mouguiama-Daouda, P., Hombert, J. M., Froment, A., Perry, G. H., Barreiro, L. B., Verdu, P., Patin, E., & Quintana-Murci, L. (2018). The demographic history and mutational load of African hunter-gatherers and farmers. Nature Ecology and Evolution, 2(4), 721-730. https://doi.org/10.1038/s41559-018-0496-4