Abstract
BackgroundUnraveling the ancestry of ‘Afro-American’ communities is hampered by the complex demographic processes that took place during the Transatlantic Slave Trade (TAST) and the (post-)colonization periods. ‘Afro-Bolivians’ from the subtropical Yungas valleys constitute small and isolated communities that live surrounded by the predominant Native American community of Bolivia. By genotyping >580,000 SNPs in two ‘Afro-Bolivians’, and comparing these genomic profiles with data compiled from more than 57 African groups and other reference ancestral populations (n = 1,161 in total), we aimed to disentangle the complex admixture processes undergone by ‘Afro-Bolivians’.ResultsThe data indicate that these two genomes constitute a complex mosaic of ancestries that is approximately 80 % of recent African origin; the remaining ~20 % being European and Native American. West-Central Africa contributed most of the African ancestry to ‘Afro-Bolivians’, and this component is related to populations living along the Atlantic coast (i.e. Senegal, Ghana, Nigeria). Using tract length distribution of genomic segments attributable to distinct ancestries, we could date the time of admixture in about 400 years ago. This time coincides with the maximum importation of slaves to Bolivia to compensate the diminishing indigenous labor force needed for the development of the National Mint of Potosí.ConclusionsOverall, the data indicate that the genome of ‘Afro-Bolivians’ was shaped by a complex process of admixture occurring in America among individuals originating in different West-Central African populations; their genomic mosaics received additional contributions of Europeans and local Native Americans (e.g. Aymaras).Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2520-x) contains supplementary material, which is available to authorized users.
Highlights
Unraveling the ancestry of ‘Afro-American’ communities is hampered by the complex demographic processes that took place during the Transatlantic Slave Trade (TAST) and thecolonization periods
These analyses were carried out using separately the population sets from The 1000 Genomes Project and a large dataset of African populations
The second round of analysis (Additional file 2B; 25 K SNPs), using a panel of 57 African datasets, indicates that the highest values of IBS for the two Tocaña are with the Yoruba (Nigeria); followed by a set of populations that are mainly from West-Central Africa
Summary
Unraveling the ancestry of ‘Afro-American’ communities is hampered by the complex demographic processes that took place during the Transatlantic Slave Trade (TAST) and the (post-)colonization periods. Geneticists have aimed to unravel the complex patterns of admixture occurring in America as a consequence of the European colonization and the TAST. It is known that African mtDNA lineages in America prevailed in the Northeast of Brazil [11], and are widely distributed in ‘Afro-Colombians’ of Chocó [12,13,14]. According to autosomal DNA, many populations in Brazil are principally of European ancestry, but there exists a North–South gradient towards an increased African ancestry in the North, Northeast, and Centre-West [15]. Moreno-Estrada et al [17] investigated the population genetic history of the Caribbean by characterizing patterns of genome-wide variation. These authors found that admixed genomes can be traced back to distinct sub-continental source populations, even in situations where limited preColumbian Caribbean haplotypes survived
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
