As in other Latin American populations, Argentinians are the result of the admixture amongst different continental groups, mainly from America and Europe, and to a lesser extent from Sub-Saharan Africa. However, it is known that the admixture processes did not occur homogeneously throughout the country. Therefore, considering the importance for anthropological, medical and forensic researches, this study aimed to investigate the population genetic structure of the Argentinian Patagonia, through the analysis of 46 ancestry informative markers, in 433 individuals from five different localities. Overall, in the Patagonian sample, the average individual ancestry was estimated as 35.8% Native American (95% CI: 32.2–39.4%), 62.1% European (58.5–65.7%) and 2.1% African (1.7–2.4%). Comparing the five localities studied, statistically significant differences were observed for the Native American and European contributions, but not for the African ancestry. The admixture results combined with the genealogical information revealed intra-regional variations that are consistent with the different geographic origin of the participants and their ancestors. As expected, a high European ancestry was observed for donors with four grandparents born in Europe (96.8%) or in the Central region of Argentina (85%). In contrast, the Native American ancestry increased when the four grandparents were born in the North (71%) or in the South (61.9%) regions of the country, or even in Chile (60.5%). In summary, our results showed that differences on continental ancestry contribution have different origins in each region in Patagonia, and even in each locality, highlighting the importance of knowing the origin of the participants and their ancestors for the correct interpretation and contextualization of the genetic information.

3940 As for other Latin American populations, Argentinians are the result of the admixture 41 amongst different continental groups, mainly from America and Europe, and to a lesser 42 extent from Sub-Saharan Africa. However, it is known that the admixture processes did 43 not occur homogeneously throughout the country. Therefore, considering the importance 44 for anthropological, medical and forensic researches, this study aimed to investigate the 45 population genetic structure of the Argentinian Patagonia, through the analysis of 46 46 ancestry informative markers, in 433 individuals from five different localities. Overall, in 47 the Patagonian sample, the average individual ancestry was estimated as 35.8% Native 48 American (95% CI: 32.2-39.4%), 62.1% European (58.5-65.7%) and 2.1% African (1.7-49 2.4%). Comparing the five localities studied, statistically significant differences were 50 observed for the Native American and European contributions, but not for the African 51 ancestry. The admixture results combined with the genealogical information revealed 52 intra-regional variations that are consistent with the different geographic origin of the 53 participants and their ancestors. As expected, a high European ancestry was observed for 54 donors with four grandparents born in Europe (96.8%) or in the Central region of 55 Argentina (85%). In contrast, the Native American ancestry increased when the four 56 grandparents were born in the North (71%) or in the South (61.9%) regions of the country, 57 or even in Chile (60.5%). In summary, our results showed that differences on continental 58 ancestry contribution have different origins in each region in Patagonia, and even in each 59 locality, highlighting the importance of knowing the origin of the participants and their 60 ancestors for the correct interpretation and contextualization of the genetic information.

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Objectives: 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. Methods: 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.Results: 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. Conclusions: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.

Patagonia, a cul-de-sac for the continental dispersal of Homo sapiens into the Americas, has been extensively analyzed by archaeologists and bioanthropologists. Despite its deep and rich archaeological record, the genetic make up of its pre-contact inhabitants is barely known. We present the analysis of 19 mitogenomes recovered by NGS from archaeological sites in Central Patagonia (Chubut, Argentina). 15 are pre-contact samples, (6,010-770YBP), and four are samples from historical times (550-310YBP). Preservation of the samples was extraordinary, with endogenous DNA values up to 68%. Preliminary analysis indicates that mtDNA genomes. Central Patagonia belong to haplogroups B2 (21%), C1b (21%), C1c (5%), D1 (47%) and D4h3a (5%). This is surprising when compared with a database of 19,000 control region sequences and >2,100 mitogenomes of Native American origin: 1) While modern indigenous populations from Northern and Central Patagonia of Argentina and Chile derive 41-54% of their maternal lineages from clades B2i2 and C1b13, none of these are present in our dataset; 2) 75% of our B2 and C1b lineages share derived polymorphism with lineages so far known to be present only in modern Central-Western Argentina; and 3) although modern Patagonians carry the highest continental frequencies of D1g, the ancient set is enriched mostly in D1g5, a lineage widely distributed from South-Central Andes to Tierra del Fuego (including two samples with private motifs not described before). The upcoming analysis of the nuclear portion of these samples will help us better understand migratory and admixture processes in the Patagonian region.