Uniparental origins of the admixed Argentine Patagonia

We aimed to contribute to the understanding of the ancient geographic origins of the uniparentally inherited markers in modern admixed Argentinian populations from central Patagonia with new information provided for the city of Trelew. We attempted to highlight the importance of combining different genetic markers when studying population history.

The mtDNA control region sequence was typified in 89 individuals and 12 Y-STR and 15 Y-SNP loci were analyzed in 66 males. With these data, analysis of molecular variance and Network analyses were carried out. We exhaustively compared the modern data with ancient mtDNA information. Finally, we tested the differences in continental origins estimated by uniparental and previously published biparental markers.

Native American mtDNAs (53.9%) increased when maternal ancestors were born in the northern (81.8%) and southern (58.5%) regions of Argentina or in Chile (77.8%). Population substructure was only observed for Y-chromosome haplotypes. Some mtDNA haplogroups have been present in the area for at least ca. 2762-2430 and ca. 500 (D1g and D1g4 haplogroups) and ca. 6736 and ca. 6620 (C1b and C1c haplogroups) years, respectively. In contrast, haplogroups B2i2 and C1b13, frequent in modern Patagonia populations, had not been found in previous ancient DNA studies of the region.

The results suggest that Native American ancestry is well preserved in the region. Trelew samples had characteristic native mtDNA haplogroups previously described in Chilean and Argentine Patagonian populations, but not observed in ancient samples until now. These findings support the idea that these lineages have a recent regional origin. Finally, the estimated proportions of continental ancestry depend on the genetic marker analyzed.