MARCH 2015: Genetic perspective of biogeographic ancestry in African American descendants from South America

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.

Maroon men and a child in Suriname, photo taken between 1910-1935

Maroon men and a child in Suriname, photo taken between 1910-1935

Title: Genetic perspective of biogeographic ancestry in African American descendants from South America

Authors: Cesar Fortes-Lima and Jean-Michel Dugoujon

The Atlantic slave trade, from the 15th to 19th centuries, changed dramatically the demography of the New World. Noir Marron populations, for example, are direct descendants of African slaves who escaped from Dutch plantations in present-day Suriname, and formed independent societies in French Guiana that still conserve their African roots. To answer questions regarding the African origin of African descendants from different geographical regions in South America, we analysed the maternally (mtDNA genome) and paternally (Y-chromosome) inherited DNA and bi-parental markers (4.5 million autosomal SNPs) of four Noir Marron communities; Aluku, Paramaka, Ndjuka, and Saramaka, as well as other populations with noteworthy African heritage from the Choco department in northwest Colombia and Rio de Janeiro in southeastern Brazil.

Uniparental markers uncovered different population histories in these communities as a result of their colonial past and historical admixture events. The highest African component was detected among Noir Marron communities (92.92 to 99.70 %) in agreement with previous linguistic and genetic studies. Phylogenetic reconstructions added further support to a West African origin from the Bight of Benin. Furthermore, admixture estimates revealed a certain degree of gene flow between Afro-Colombian and Native American (Hg A2, B2d, and C1d) populations as shown by complete mtDNA analysis. Conversely, the Afro-Brazilian Y-chromosome analysis (17 Y-STRs and 96 Y-SNPs) highlighted a significant tendency of preferential marriages between European men (Hg R1b1a2-M269) and African women in the past.

Additionally, ancestry informative markers (AIMs) were studied to investigate genome variation within African Americans and their African specific ancestry. The results of admixture analyses of bi-parental markers were also varied: high African ancestral membership proportions in Noir Marron (98.90 %), and genetic links between Afro-Colombian and Native American groups (12.5 %) and Afro-Brazilian and European groups (21.6 %). In conclusion, this study determines some potential founding groups that played a significant role in the African identity of these communities, and gives important information on ancestral mixture patterns.

Categorized: latest