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

Abstract

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. Author SummaryThe human genetic diversity in Argentina reflects demographic processes during which the European colonists invaded a territory where Native American populations were settled. During the colonial period, the slave trade also prompted many African people to move to Argentina. Little is known about the origins of these three continental ancestry components in Argentinean populations nowadays. Genotyping data for 87 admixed individuals throughout Argentina was generated and data from the literature was re-analyzed to shed light on this question. We confirmed that most of the European genetic ancestry comes from the South, although several individuals are related to Northern Europeans. We confirmed that the African origins in Argentina mainly trace back from Western and Central/Western regions, and we document some proportion of Eastern African origins poorly described before. As for the Native American ancestry, we identified that it can be divided into four main components that correspond to Central Chile/Patagonia, Subtropical and Tropical Forests, Central Andes and Central Western region of Argentina. In order to understand the specificity of the genetic diversity in Argentina, more effort is required to generate specific massive genomic knowledge at the local level.