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We present new data and analysis on the genetic variation of contemporary inhabitants of central Argentina, including a total of 812 unrelated individuals from 20 populations. Our goal was to bring new elements for understanding micro-evolutionary and historical processes that generated the genetic diversity of the region, using molecular markers of uniparental inheritance (mitochondrial DNA and Y chromosome). Almost 76% of the individuals show mitochondrial lineages of American origin. The Native American haplogroups predominate in all surveyed localities, except in one. The larger presence of Eurasian maternal lineages were observed in the plains (Pampas) of the southeast, whereas the African lineages are more frequent in northern Córdoba. On the other hand, the analysis of 258 male samples reveals that 92% of them present Eurasian paternal lineages, 7% carry Native American haplogroups, and only 1% of the males show African lineages. The maternal lineages have high genetic diversity homogeneously distributed throughout central Argentina, probably as result of a recent common origin and sustained gene flow. Migratory events that occurred in colonial and recent times should have contributed to hiding any traces of differentiation that might have existed in the past. The analysis of paternal lineages showed also homogeneous distribution of the variation together with a drastic reduction of the native male population.

AbstractThe Gran Chaco region is a vast subtropical plain in South America that covers part of the territories of Argentina, Paraguay, and Bolivia, being the refuge of some of the last hunter-gatherer groups remaining in South America. Culturally as well as ecologically, the Gran Chaco is a transitional zone between the tropical plains of the Amazon Basin and the Pampas of Argentina. Along its western border it was wide-open to influences from the Andean cultures, and in the east it abutted on a subtropical region inhabited by Tupí-Guaraní tribes. In this paper we present a synthesis of the principal findings of a long term study on the genetic structure of native populations of the Gran Chaco using an assortment of morphological (anthropometrics and dermatoglyphics) and molecular markers (mitochondrial haplogroups and HVR-I sequences, Y-chromosome markers, and nuclear STRs). In general, the biological evidence demonstrates that the Gran Chaco tribes present high genetic diversity and low differentiation among populations, when compared to other regions of South America. The only exception is the Ayoreo, a population with unique genetic and morphological patterns, being an outlier not only in relation to the rest of the Gran Chaco populations but also to any other native group of South America.

Apoproteins (also known as apolipoproteins) have been studied extensively because of their role in lipid transport, association between specific genotypes and elevated serum lipid levels, and increased risk of heart disease. There is considerable genetic variation in the geographic distributions of these markers, with a north‐south cline of the APOE*4 allele observed in Europe by Lucotte et al. ([1997] Hum Biol 69:253–262). This study compares the frequencies of seven APO (APOA1 −75 bp, APOA1 +83 bp, APOB Ins/Del, APOB XbaI, APOC3 SstI, and APOE) and LPL loci in Mennonite populations from Kansas and Nebraska. In total, 277 individuals were sampled from Goessel, Meridian, Garden View, and Lone Tree in 2002–2004. In addition, DNA samples that were collected in 1981 from Henderson, Nebraska, were genotyped for the seven APO and LPL loci. Of the seven APO and LPL loci tested, only one locus, APOB XbaI, departed significantly from Hardy‐Weinberg equilibrium, with an unexpected excess of observed heterozygotes. The frequencies of the several APO loci are unique among the Mennonites, separating them from other European populations. A bidimensional scaling representation of Reynold's coancestry distances based on allelic frequencies of the seven APO and LPL markers in five Mennonite congregations fails to represent schematically the known patterns of fission. It is unclear whether the observed patterns are due to selection operating on these loci or whether genetic drift, small populations sizes, or a lack of statistical power of these biallelic loci distort the observed genetic relationship among congregations. Am. J. Hum. Biol. 17:593–600, 2005. © 2005 Wiley‐Liss, Inc..