The Phylogeography of African Brazilians

Abstract

Background/Aims: Approximately four million Africans were taken as slaves to Brazil, where they interbred extensively with Amerindians and Europeans. We have previously shown that while most White Brazilians carry Y chromosomes of European origin, they display high proportions of African and Amerindian mtDNA lineages, because of sex-biased genetic admixture. Methods: We studied the Y chromosome and mtDNA haplogroup structure of 120 Black males from Sao Paulo, Brazil. Results: Only 48% of the Y chromosomes, but 85% of the mtDNA haplogroups were characteristic of sub-Saharan Africa, confirming our previous observation of sexually biased mating. We mined literature data for mtDNA and Y chromosome haplogroup frequencies for African native populations from regions involved in Atlantic Slave Trade. Principal Components Analysis and Bayesian analysis of population structure revealed no genetic differentiation of Y chromosome marker frequencies between the African regions. However, mtDNA examination unraveled considerable genetic structure, with three clusters at Central-West Africa, West Africa and Southeast Africa. A hypothesis is proposed to explain this structure. Conclusion: Using these mtDNA data we could obtain for the first time an estimate of the relative ancestral contribution of Central-West (0.445), West (0.431) and Southeast Africa (0.123) to African Brazilians from Sao Paulo. These estimates are consistent with historical information.

Gene Encoding Duffy Antigen/Receptor for Chemokines Is Associated with Asthma and IgE in Three Populations

“…The demographic history of these four populations is similar, that is, they each share common West African ancestors resulting from the African slave trade; however, each of these four populations had a different dynamic of admixture with Europeans and native Americans (15,(32)(33)(34) and they currently reside in diverse environmental settings. Although African Americans in general, and individuals from Baltimore and Washington, DC in particular, have a high African ancestry proportion (15,35,36) (32) and Brazilians (33,37), specific environmental factors and potential gene-environment interactions are likely to be considerably different between African American and the other tropical populations, which could account for differences in the results observed here. The significantly lower mean total serum IgE levels among the African American group (2.57 6 0.66) compared with African Caribbeans (2.79 6 0.67), Colombians (2.95 6 0.55), and Brazilians (3.42 6 0.52; see Table 1), all of which were based in the tropics, could suggest less severe allergic diathesis in that group.…”

DNA tests probe the genomic ancestry of Brazilians

“…Next, for further confirmation, we studied mtDNA lineages in 120 black individuals from the city of São Paulo (13). The results, as expected, showed a mirror image of those previously found in white Brazilians: on the one hand, 85% of the lineages originated in Sub-Saharan Africa, 12% were from Amerindians and only 3% were from Europe; on the other, only 48% of the Y chromosome lineages originated from Sub-Saharan Africa (the vast majority belonging to haplogroups E3a7 and E3a*).…”

A minimum set of ancestry informative markers for determining admixture proportions in a mixed American population: the Brazilian set

“…Colonization history shows that the main contributing ancestral populations were European and African, with Amerindians contributing to a lesser extent. 4 Along the five geographical regions of Brazil (North, Northeast, Center-West, Southeast, and South), following a North to South gradient, European ancestry increases in all urban populations, achieving the highest values in populations from the South. The populations in the North have a significant proportion of Native American ancestry, which is approximately twice as high as that of African ancestry.…”