Population Histories and Genomic Diversity of South American Natives

South America is home to one of the most culturally diverse present-day native populations. However, the dispersion pattern, genetic substructure, and demographic complexity within South America are still poorly understood. Based on genome-wide data of 58 native populations, we provide a comprehensive scenario of South American indigenous groups considering the genomic, environmental, and linguistic data. Clear patterns of genetic structure were inferred among the South American natives, presenting at least four primary genetic clusters in the Amazonian and savanna regions and three clusters in the Andes and Pacific coast. We detected a cline of genetic variation along a west-east axis, contradicting a hard Andes-Amazon divide. This longitudinal genetic variation seemed to have been shaped by both serial population bottlenecks and isolation by distance. Results indicated that present-day South American substructures recapitulate ancient macroregional ancestries and western Amazonia groups show genetic evidence of cultural exchanges that led to language replacement in precontact times. Finally, demographic inferences pointed to a higher resilience of the western South American groups regarding population collapses caused by the European invasion and indicated precontact population reductions and demic expansions in South America.

Automated summary

Based on genome-wide data of 58 native populations, this study revealed clear patterns of genetic structure among South American natives, showing at least four primary genetic clusters in the Amazonian and savanna regions and three clusters in the Andes and Pacific coast. The longitudinal genetic variation along a west-east axis seems to have been shaped by population bottlenecks and isolation by distance, while the present-day South American substructures recapitulate ancient macroregional ancestries and suggest cultural exchanges in the western Amazonia groups that led to language replacement in precontact times. Demographic inferences indicate a higher resilience of western South American groups to population collapses caused by the European invasion and suggest precontact population reductions and demic expansions in South America.