RESUMEN
Recent studies have expanded and refined the founding haplogroups of the Americas using whole mitochondrial (mtDNA) genome analysis. In addition to pan-American lineages, specific variants have been identified in a number of studies that show higher frequencies in restricted geographical areas. To further characterize Native American maternal lineages and specifically examine local patterns within South America, we analyzed 12 maternally unrelated Yekuana whole mtDNA genomes from one village (Sharamaña) that include the four major Native American haplogroups A2, B2, C1, and D1. Based on our results, we propose a reconfiguration of one subhaplogroup A2 (A2aa) that is specific to South America and identify other singleton branches across the four haplogroups. Furthermore, we show nucleotide diversity values that increase from north to south for haplogroups C1 and D1. The results from our work add to the growing mitogenomic data that highlight local phylogenies and support the rapid genetic differentiation of South American populations, which has been correlated with the linguistic diversity in the region by previous studies.
Asunto(s)
Genoma Mitocondrial , Estudio de Asociación del Genoma Completo , Indígenas Sudamericanos/genética , Filogenia , Haplotipos , Humanos , Venezuela/etnologíaRESUMEN
Recent studies of the Uruguayan population revealed different amounts of Amerindian and African genetic contributions. Our previous analysis of Afro-Uruguayans from the capital city of the Department of Cerro Largo showed a high proportion of African genes, and the effects of directional mating involving Amerindian women. In this paper, we extended the analysis to a sample of more than 100 individuals representing a random sample of the population of the whole Department. Based on 18 autosomal markers and one X-linked marker, we estimated 82% European, 8% Amerindian, and 10% African contributions to their ancestry, while from seven mitochondrial DNA site-specific polymorphic markers and sequences of hypervariable segment I, we determined 49% European, 30% Amerindian, and 21% African maternal contributions. Directional matings between Amerindian women and European men were detected, but differences involving Africans were not significant. Data about the specific origins of maternal lineages were also provided, and placed in a historical context.
Asunto(s)
Antígenos de Grupos Sanguíneos/clasificación , Cromosomas Humanos Y/genética , ADN Mitocondrial/genética , Genética de Población , Polimorfismo Genético , Población Negra/etnología , Población Negra/genética , Antígenos de Grupos Sanguíneos/sangre , Cromosomas Humanos Y/clasificación , ADN Mitocondrial/clasificación , Demografía , Emigración e Inmigración , Frecuencia de los Genes/genética , Genotipo , Haplotipos/genética , Humanos , Indígenas Sudamericanos/etnología , Indígenas Sudamericanos/genética , Fenotipo , Filogenia , Análisis de Secuencia de ADN , Uruguay/etnología , Población Blanca/etnología , Población Blanca/genéticaRESUMEN
This study reevaluates the hypothesis in Demarchi et al. (2001 Am. J. Phys. Anthropol. 115:199-203) that Gran Chaco peoples demonstrate a unique pattern of genetic diversity due to a distinct regional population history. Specifically, they found populations in the central part of the Gran Chaco, or Central Chaco, to have higher within- and lower between-population mitochondrial DNA (mtDNA) haplogroup frequency variation compared to populations in other South American regions. To test this hypothesis of regional uniqueness, we applied analytical and simulation methods to mtDNA first hypervariable (HVI) region sequence data from a broad set of comparative South and Central American population samples. Contrary to the results of Demarchi et al. (2001 Am. J. Phys. Anthropol. 115:199-203), we found that the Gran Chaco's regional within-population diversity is about average among regions, and populations are highly differentiated from each other. When we limited the scale of analysis to the Central Chaco, a more localized subregion of the Gran Chaco, our results fell more in line with the original findings of Demarchi et al. (2001 Am. J. Phys. Anthropol. 115:199-203). Still, we conclude that neither the Gran Chaco regional pattern, nor the Central Chaco subregional pattern, is unique within South America. Nonetheless, the Central Chaco pattern accords well with the area's history, including pre-European contact lifeways and the documented historical use of the area as an interregional crossroads. However, we cannot exclude post-European contact disruption of traditional mating networks as an equally plausible explanation for the observed diversity pattern. Finally, these results additionally inform broader models of South American genetic diversity. While other researchers proposed an east-west continental division in patterns of genetic variation (e.g., Fuselli et al. 2003 Mol. Biol. Evol. 20:1682-1691), we found that in the geographically intermediate Central Chaco, a strict east-west divide in genetic variation breaks down. We suggest that future genetic characterizations of the continent, and subsequent interpretations of evolutionary history, involve a broad regional sampling of South American populations.