Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
Departament de Ciències Experimentals i de la Salut, Institute of Evolutionary Biology (CSIC-UPF), Universitat Pompeu Fabra, Barcelona, Spain.
Genome Biol Evol. 2019 Sep 1;11(9):2593-2604. doi: 10.1093/gbe/evz161.
After the colonization of the Americas by Europeans and the consequent Trans-Atlantic Slave Trade, most Native American populations in eastern Brazil disappeared or went through an admixture process that configured a population composed of three main genetic components: the European, the sub-Saharan African, and the Native American. The study of the Native American genetic history is challenged by the lack of availability of genome-wide samples from Native American populations, the technical difficulties to develop ancient DNA studies, and the low proportions of the Native American component in the admixed Brazilian populations (on average 7%). We analyzed genome-wide data of 5,825 individuals from three locations of eastern Brazil: Salvador (North-East), Bambui (South-East), and Pelotas (South) and we reconstructed populations that emulate the Native American groups that were living in the 16th century around the sampling locations. This genetic reconstruction was performed after local ancestry analysis of the admixed Brazilian populations, through the rearrangement of the Native American haplotypes into reconstructed individuals with full Native American ancestry (51 reconstructed individuals in Salvador, 45 in Bambui, and 197 in Pelotas). We compared the reconstructed populations with nonadmixed Native American populations from other regions of Brazil through haplotype-based methods. Our results reveal a population structure shaped by the dichotomy of Tupi-/Jê-speaking ancestry related groups. We also show evidence of a decrease of the diversity of nonadmixed Native American groups after the European contact, in contrast with the reconstructed populations, suggesting a reservoir of the Native American genetic diversity within the admixed Brazilian population.
在欧洲人对美洲的殖民和随之而来的跨大西洋奴隶贸易之后，巴西东部的大多数美洲原住民人口消失或经历了混合过程，形成了由三个主要遗传成分组成的人口：欧洲人、撒哈拉以南非洲人和美洲原住民。对美洲原住民遗传史的研究受到以下因素的挑战：缺乏来自美洲原住民群体的全基因组样本，开发古代 DNA 研究的技术困难，以及混合巴西人群中美洲原住民成分的比例较低（平均为 7%）。我们分析了来自巴西东部三个地点的 5825 个人的全基因组数据：萨尔瓦多（东北部）、班比乌（东南部）和佩洛塔斯（南部），并重建了模拟 16 世纪采样地点周围生活的美洲原住民群体的人口。在对混合巴西人群进行局部祖先分析后，通过将美洲原住民单倍型重新排列到具有完整美洲原住民祖先的重建个体中（萨尔瓦多有 51 个重建个体，班比乌有 45 个，佩洛塔斯有 197 个），进行了这种遗传重建。我们通过基于单倍型的方法将重建的人群与来自巴西其他地区的非混合美洲原住民人群进行了比较。我们的结果揭示了由与图皮语/热伊语有关的祖先相关群体的二分法形成的人口结构。我们还提供了证据表明，与重建的人群相比，在欧洲人接触后，非混合的美洲原住民群体的多样性减少，这表明在混合的巴西人群中存在美洲原住民遗传多样性的储备。
