Is the genetic structure of Gran Chaco populations unique? Interregional perspectives on native South American mitochondrial DNA variation

Abstract

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.

Gender bias in the multiethnic genetic composition of central Argentina

“…In contrast, the basal HVS-I haplotype of D1 (T16362C T16325C) was not detected in our sample. However, we found 11 identical matches of the most common D1 haplotype C16223T C16242T T16311C T16325C T16362C, ten of them in other Argentinean populations: four matches in the Mapuches (Ginther et al 1993) and the rest in the Pilagá and Wichí (Cabana et al 2006) and in the Coyas (Á lvarez-Iglesias et al 2007). Two other matches were also observed in the Genographic database (https://www3.nationalgeographic.com/ genographic/resources.html).…”

“…Five out of nine of the A2 haplotypes match with the basal A2 European and Native American samples plus the one from Córdoba analyzed in this study, whereas the nested small PCA plot includes three additional sub-Saharan African samples. References for population samples are as follows: a Africa (green dots): Mozambique (Salas et al 2002), Angola (Plaza et al 2004), Cabinda (Beleza et al 2005); b Europe (blue dots): Italy (Bini et al 2003), Galicia from Spain (Salas et al 1998), and Germany (Lutz et al 1998); and c America (red dots): Mexico (Green et al 2000), Mapuche from Chile (Moraga et al 2000), Guarani Kaiowá from Brazil (Marrero et al 2007), Coya (Á lvarez-Iglesias et al 2007), Toba and Wichí from Argentina (Cabana et al 2006), Navajo (Monson et al 2002), Ayoreo from Bolivia and Paraguay (Dornelles et al 2004), Ngobe from Panamá (Kolman et al 1995), Córdoba (this study) …”

Population Genetic Structure of Traditional Populations in the Peruvian Central Andes and Implications for South American Population History

“…Prior characterizations of western Andean population genetic variation assume a strong distinction from eastern South American populations. In our reanalysis, the contrast between "west" and "east" is not as stark as reported previously.In the case of mtDNA, the relative comparison between "west" and "east"is inconsistent with previous reports (i.e., Fuselli et al 2003;Cabana et al 2006). …”

Genetic uniqueness of the Waorani tribe from the Ecuadorian Amazon

“…The genetic variability observed through the analysis of 10 X-chromosome molecular markers (0.569) showed the lowest diversity observed to date in any South American population , and is consistent with previous findings in isolated populations . In contrast to some Amazonian groups such as the Waorani, populations from Gran Chaco have been reported to show a greater history of interpopulation contacts, and therefore, of genetic admixture (Cabana et al, 2006). However, a comparative analysis of the allele distribution of X-chromosome markers between the Waorani and Gran Chaco panmictic populations showed some similarities, especially for marker DXS9898, characterized by the presence of very few alleles.…”