Continental Origin for Q Haplogroup Patrilineages in Argentina and Paraguay.

Haplogroup Q originated in Eurasia around 30,000 years ago. It is present in Y-chromosomes from Asia and Europe at rather low frequencies. Since America is undoubtedly one of the continents where this haplogroup is highly represented, it has been defined as one of the founding haplogroups. Its M3 clade has been early described as the most frequent, with pan-American representation. However, it was also possible to find several other haplogroup Q clades at low frequencies. Numerous mutations have been described for haplogroup Q, allowing analysis of its variability and assignment of its geographic origin. We have analyzed 442 samples of unrelated men from Argentina and Paraguay belonging to haplogroup Q; here we report specifically on 27 Q (xM3) lineages. We tested 3 single-nucleotide polymorphisms (SNPs) by amplified product-length polymorphism (APLP) analysis, 3 SNPs for restriction fragment length polymorphism (RFLP) analysis, 15 SNPs by Sanger sequencing, and 17 short tandem repeats (STRs). Our approach allowed us to identify five subhaplogroups. Q-M3 and Q-CTS2730/Z780 are undoubtedly autochthonous lineages and represent the most frequent subhaplogroups, with significant representation in self-defined aboriginal populations, and their autochthonous status has been previously described. The aim of present work was to identify the continental origin of the remaining Q lineages. Thus, we analyzed the STR haplotypes for the samples and compared them with haplotypes described by other authors for the rest of the world. Even when haplogroup Q lineages have been extensively studied in America, some of them could have their origin in post-Columbian human migration from Europe and Middle East.

Fine-scale genomic analyses of admixed individuals reveal unrecognized genetic ancestry components in Argentina.

Similarly to other populations across the Americas, Argentinean populations trace back their genetic ancestry into African, European and Native American ancestors, reflecting a complex demographic history with multiple migration and admixture events in pre- and post-colonial times. However, little is known about the sub-continental origins of these three main ancestries. We present new high-throughput genotyping data for 87 admixed individuals across Argentina. This data was combined to previously published data for admixed individuals in the region and then compared to different reference panels specifically built to perform population structure analyses at a sub-continental level. Concerning the Native American ancestry, we could identify four Native American components segregating in modern Argentinean populations. Three of them are also found in modern South American populations and are specifically represented in Central Andes, Central Chile/Patagonia, and Subtropical and Tropical Forests geographic areas. The fourth component might be specific to the Central Western region of Argentina, and it is not well represented in any genomic data from the literature. As for the European and African ancestries, we confirmed previous results about origins from Southern Europe, Western and Central Western Africa, and we provide evidences for the presence of Northern European and Eastern African ancestries.