Programa de Pós-Graduação em Biologia Animal, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
Programa de Pós-Graduação em Genética e Biologia Molecular, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
Am J Hum Biol. 2019 May;31(3):e23243. doi: 10.1002/ajhb.23243. Epub 2019 Apr 23.
The major aim of this article was to estimate the demographic impact of European arrival and colonization over Native American populations from southern Brazil and Uruguay. We also compared the mitochondrial DNA (mtDNA) genetic diversity, structure, and demography of Native American lineages present in current indigenous (Natives) and nonindigenous admixed (Admixed) populations to estimate the effective population size (N ) of contemporary and ancestral (pre-Columbian) Native American populations.
We retrieved published mtDNA sequences from Native (n = 396) and Admixed (n = 309) populations from southern Brazil, Uruguay, and surrounding areas. We conducted genetic diversity, structure, and demographic analyses. Finally, we used Approximate Bayesian Computation to estimate the N for current Native, Admixed, and pre-Columbian Native American populations.
We found higher Native American mtDNA genetic diversity in admixed rather than in indigenous populations (131/309 vs 27/396 different haplotypes, respectively). Only Admixed populations maintained ancient signals of the Native American population expansion approximately 14 to 17 kya, which have decayed in Natives. Our N estimates suggest that Natives represent only 0.33% (0.18%-1.19%) of the N for ancestral pre-Columbian indigenous populations.
Admixed populations represent an important genetic reservoir of Native American lineages, many of which are extinct in contemporary indigenous populations. In addition, the Native American lineages present in Admixed populations retain part of the past demographic history of Native Americans. The intensity of the reduction is congruent with historical accounts of strong indigenous depopulation during the colonization process.
本文的主要目的是估算欧洲人抵达和殖民对巴西南部和乌拉圭的美洲原住民人口的人口统计学影响。我们还比较了当前土著（原住民）和非土著混合（混血）人群中存在的美洲原住民谱系的线粒体 DNA（mtDNA）遗传多样性、结构和人口动态，以估计当代和祖先（前哥伦布时期）美洲原住民人口的有效种群大小（N）。
我们从巴西南部、乌拉圭及其周边地区的原住民（n=396）和混血（n=309）人群中检索了已发表的 mtDNA 序列。我们进行了遗传多样性、结构和人口动态分析。最后，我们使用近似贝叶斯计算来估计当前原住民、混血和前哥伦布时期美洲原住民人口的 N。
我们发现，混血人群中的美洲原住民 mtDNA 遗传多样性高于原住民人群（分别为 131/309 个和 27/396 个不同的单倍型）。只有混血人群保留了大约 14 到 17 千年前美洲原住民人口扩张的古老信号，而在原住民中已经消失。我们的 N 估计表明，原住民仅占祖先前哥伦布时期原住民人口 N 的 0.33%（0.18%-1.19%）。
混血人群代表了美洲原住民谱系的一个重要遗传库，其中许多在当代原住民人群中已经灭绝。此外，混血人群中存在的美洲原住民谱系保留了部分美洲原住民过去的人口历史。这种减少的强度与殖民过程中强烈的土著人口减少的历史记载相符。
