Genome-wide data from the Bubi of Bioko Island clarifies the Atlantic fringe of the Bantu dispersal

Pere Gelabert (1) , Manuel Ferrando-Bernal (1) , Toni De-Dios (1) , Benedetta Mattorre (2) , Elena Campoy (3) , Amaya Gorostiza (4) , Etienne Patin (5) , Antonio Gonzalez-Martin (3) , Carles Lalueza-Fox (1)

1 UPF - Universitat Pompeu Fabra [Barcelona]
2 UniFI - Università degli Studi di Firenze = University of Florence = Université de Florence
3 UCM - Universidad Complutense de Madrid = Complutense University of Madrid [Madrid]
4 GENOMICA S.A.U.
5 Génétique Evolutive Humaine - Human Evolutionary Genetics

BACKGROUND: Bioko is one of the few islands that exist around Africa, the most genetically diverse continent on the planet. The native Bantu-speaking inhabitants of Bioko, the Bubi, are believed to have colonized the island about 2000 years ago. Here, we sequenced the genome of thirteen Bubi individuals at high coverage and analysed their sequences in comparison to mainland populations from the Gulf of Guinea. RESULTS: We found that, genetically, the closest mainland population to the Bubi are Bantu-speaking groups from Angola instead the geographically closer groups from Cameroon. The Bubi possess a lower proportion of rainforest hunter-gatherer (RHG) ancestry than most other Bantu-speaking groups. However, their RHG component most likely came from the same source and could have reached them by gene flow from the mainland after island settlement. By studying identity by descent (IBD) genomic blocks and runs of homozygosity (ROHs), we found evidence for a significant level of genetic isolation among the Bubi, isolation that can be attributed to the island effect. Additionally, as this population is known to have one of the highest malaria incidence rates in the world we analysed their genome for malaria-resistant alleles. However, we were unable to detect any specific selective sweeps related to this disease. CONCLUSIONS: By describing their dispersal to the Atlantic islands, the genomic characterization of the Bubi contributes to the understanding of the margins of the massive Bantu migration that shaped all Sub-Saharan African populations.

Mots clés: Population genetics; Bantu-speaking groups; Bioko Island; Bubi; Isolation

Domaines: Génétique des populations [q-bio.PE]; Génétique humaine

Pere Gelabert, Manuel Ferrando-Bernal, Toni De-Dios, Benedetta Mattorre, Elena Campoy, et al.. Genome-wide data from the Bubi of Bioko Island clarifies the Atlantic fringe of the Bantu dispersal. BMC Genomics, 2019, 20 (1), pp.179. ⟨10.1186/s12864-019-5529-0⟩. ⟨hal-02353006⟩