Brazilian quilombos: A repository of Amerindian alleles.

OBJECTIVES: As a consequence of colonization of the Americas and decimation of the native population, an important portion of autochthonous genetic variation has been lost. However, some alleles have been incorporated into the growing populations of admixed mestizos. In this study, we evaluated the potential of African-derived communities in Brazil to be repositories of Amerindian alleles and, by extension, a source of information on American prehistory. METHODS: In this study, we describe the genetic variation of 15 ancestry informative markers (AIMs) of autosomal origin in two quilombos, Brazilian populations mainly of African descent, Santo Antônio do Guaporé (SAG; N = 31), and Santiago do Iguape (STI; N = 37). We compared the AIMs from these populations to those of other African-Brazilian populations, and to the Distrito Federal (N = 168), an urban population representative of Brazilian genetic diversity. RESULTS: By admixture analysis, we found that the SAG and STI communities have a much higher proportion (over 40%) of Amerindian contribution to their gene pools than other admixed Brazilian populations, in addition to marked African contributions. CONCLUSIONS: These results identify two living African-Brazilian populations that carry unique and important genetic information regarding Amerindian history. These populations will be extremely valuable in future investigations into American pre-history and Native American evolutionary dynamics.