Male ancestry structure and interethnic admixture in African-descent communities from the Amazon as revealed by Y-chromosome Strs.

Some genetic markers on both the Y chromosome and mtDNA are highly polymorphic and population-specific in humans, representing useful tools for reconstructing the past history of populations with poor historical records. Such lack of information is usually true in the case of recent African-descent populations of the New World founded by fugitive slaves throughout the slavery period in the Americas, particularly in Brazil, where those communities are known as quilombos. Aiming to recover male-derived ethnic structure of nine quilombos from the Brazilian Amazon, a total of 300 individuals, belonging to Mazagão Velho (N = 24), Curiaú (N = 48), Mazagão (N = 36), Trombetas (N = 20), Itacoã (N = 22), Saracura (N = 46), Marajó (N = 58), Pitimandeua (N = 26), and Pontal (N = 20), were investigated for nine Y-STRs (DYS393, DYS19, DYS390, DYS389 I, DYS389 II, DYS392, DYS391, DYS385 I/II). From the 169 distinct haplotypes obtained, 120 were singletons. The results suggest the West African coast as the main origin of slaves brought to Brazil (54% of male contribution); the European contribution was high (41%), while the Amerindian's was low (5%). Those results contrast with previous mtDNA data that showed high Amerindian female contribution (46.6%) in African-descent populations. AMOVA suggests that the genetic differentiation among the quilombos is mainly influenced by admixture with European. However, when restricting AMOVA to African-specific haplotypes, low differentiation was detected, suggesting great genetic homogeneity of the African founding populations and/or a later homogenization by intense slave trade inside Brazil.