RESUMO
In the 15th century, â¼900,000 Native Americans, mostly Tupí speakers, lived on the Brazilian coast. By the end of the 18th century, the coastal native populations were declared extinct. The Tupí arrived on the east coast after leaving the Amazonian basin â¼2,000 y before present; however, there is no consensus on how this migration occurred: toward the northern Amazon and then directly to the Atlantic coast, or heading south into the continent and then migrating to the coast. Here we leveraged genomic data from one of the last remaining putative representatives of the Tupí coastal branch, a small, admixed, self-reported Tupiniquim community, as well as data of a Guaraní Mbyá native population from Southern Brazil and of three other native populations from the Amazonian region. We demonstrated that the Tupiniquim Native American ancestry is not related to any extant Brazilian Native American population already studied, and thus they could be considered the only living representatives of the extinct Tupí branch that used to settle the Atlantic Coast of Brazil. Furthermore, these data show evidence of a direct migration from Amazon to the Northeast Coast in pre-Columbian time, giving rise to the Tupí Coastal populations, and a single distinct migration southward that originated the Guaraní people from Brazil and Paraguay. This study elucidates the population dynamics and diversification of the Brazilian natives at a genomic level, which was made possible by recovering data from the Brazilian coastal population through the genomes of mestizo individuals.
Assuntos
Genoma Humano/genética , Indígenas Sul-Americanos/genética , Dinâmica Populacional , Brasil , Variação Genética , Genômica , Humanos , Densidade DemográficaRESUMO
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.