Composição genética de quatros populações remanescentes de quilombos do Brasil com base em microssatélites e marcadores de ancestralidade

AUTOR(ES)

Maria Angélica Floriano Pedrosa

DATA DE PUBLICAÇÃO

2006

RESUMO

The Brazilian population is very peculiar in relation to other world populations since its formation involved the admixture of many peoples that came to Brazil since 1500, specially Amerindians, Africans and Europeans. At the present, there are in Brazil many rural semi-isolated communities identified as remnants of quilombos, which were constituted mainly by runaway slaves during the Colonial Period. It is expected that these populations preserve mainly an African genetic composition, despite the stochastic events to which they have been submitted to. Thus, this study had as a global objective the estimation of the genetic composition of four remnants of quilombos (Kalunga, Mocambo, Rio das Rãs and Riacho de Sacutiaba) and the comparison of these estimatives to the ones obtained in urban Brazilian populations. For this purpose, eight autosomal microsatellites and nine autosomal AIMs (ancestry informative markers) were genotyped. Moreover, differentiation analyses among the populations were done and an individual African Ancestry Index (IAA) was calculated. After applying the Bonferroni’s correction for multiple comparisons, it was observed only one deviation from Hardy-Weinberg Equilibrium (locus rs1129048, in Kalunga). AIMs indicated more differentiation among the communities than microsatellites. The genetic admixture analysis showed that all communities, especially Rio das Rãs and Kalunga, had a strong African contribution in their genetic composition. The estimated European contribution was also high, especially in Riacho de Sacutiaba and Mocambo. The Amerindian contribution was very important in the formation of Mocambo. Some statistical significant difference among the admixture estimatives realized with the two different markers was found. As the IAA, Mocambo presented the lowest median value, suggesting a smaller African ancestry in comparison to the other communities. Rio das Rãs and Kalunga, on the other hand, showed the greatest medians for IAA, what is in accordance to the genetic admixture estimates for these communities. The results of admixture analyses and IAAs corroborate the historical data, which points out that the quilombos were founded not only by Afrodescendants and that gene flow occurred during the histories of these populations

ASSUNTO(S)

biologia molecular strs afrodescendentes mistura genética aims

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