February 2015: The Genomic Legacy of the Transatlantic Slave Trade in the Yungas Valley of Bolivia

The EUROTAST fellows will be presenting the findings of their research at the upcoming Genetics/Heritage conference, 23-25 April at the International Slavery Museum in Liverpool. Deadline for submission has been extended to March 15. To submit a paper or to attend the conference, visit the Genetics/Heritage website.

There are some fantastic projects involved and we will feature some of the highlights in weeks to come:

4384149639_74c10a1f94_z

Las Tías, by the US Embassy Bolivia

 

Title: The Genomic Legacy of the Transatlantic Slave Trade in the Yungas Valley of Bolivia

Authors: 

Tanja Heinz, Jacobo Pardo-Seco, Jorge Mario Cárdenas, Patricia Taboada-Echalar, Vanesa Álvarez-Iglesias, Alberto Gómez-Carballa, Carla Santos, Federico Martinón-Torres, Antonio Salas

Abstract:

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. ‘Afro-Bolivians’ from the subtropical Yungas valleys constitute small and isolated communities that live surrounded by the predominant Native American community of Bolivia.

Through the combination of uniparental (mtDNA, Y chromosome) and biparental markers (AIM-Indels, SNPs) ancestry of 105 individuals from the Yungas valley (including 19 individuals from the ‘Afro-Bolivian’ community Tocaña) was analyzed. In addition, two ‘Afro-Bolivians’ were genotyped for >580,000 autosomal SNPs. The data indicate that the partitioning of mtDNA ancestry in the Yungas differs significantly from the rest of the country: 81% Native American, 18% African, and 1% European.

The great majority of ‘Afro-descendant’ mtDNA haplotypes in the Yungas (84%) concentrates in the locality of Tocaña. This high proportion of African ancestry in the Tocaña is also manifested in the Y-chromosome (44%) and in the autosomes (AIMs; 56%). In sharp contrast to previous studies on the TAST, the ancestry of about 1/3 of the ‘Afro-Bolivian’ mtDNA haplotypes can be traced to East and South East Africa.

In addition, the gender bias observed in the Yungas not only affects the partitioning of major continental ancestries in the region; the data is also compatible with a larger introgression of African females than males in the Yungas gene pool. By comparing the genomic-wide profiles of the two ‘Afro-Bolivians with data compiled from more than 57 African groups and other reference ancestral populations (n = 1,795 individuals in total), we aimed to disentangle the complex admixture processes undergone by ‘Afro-Bolivians’. These two genomes constitute a complex mosaic of ancestries that is 83-84% of African origin; the remaining 16-17% being European and Native American.

West-Central Africa contributed more than half of the African ancestry to ‘Afro-Bolivians’, and this component is related to populations living along the Atlantic coast (i.e. Senegal, Ghana, Nigeria). Contrary to expectations but in good agreement with uniparental markers, the remaining 1/3 of their African ancestry could have originated in Southeast or East Africa, with the Luhya being closely related.

Categorized: EUROTAST Reporting
Tagged: , , , , ,