Genetic Variation and Population Structure in Native Americans

TLDR

The study genotyped 678 autosomal microsatellites in 422 individuals from 24 Native American populations across the Americas and compared the data with 54 other indigenous groups worldwide, including five additional Native American groups. Native American populations exhibit lower genetic diversity and higher differentiation than other continental groups, with gradients of decreasing diversity and similarity to Siberians from the Bering Strait, greater diversity and less structure in western South America, minimal differentiation between Mesoamerican and Andean groups, evidence that coastal routes were more accessible than inland routes, and a partial concordance between genetic similarity and linguistic classification, providing new insights into the peopling of the Americas.

Abstract

We examined genetic diversity and population structure in the American landmass using 678 autosomal microsatellite markers genotyped in 422 individuals representing 24 Native American populations sampled from North, Central, and South America. These data were analyzed jointly with similar data available in 54 other indigenous populations worldwide, including an additional five Native American groups. The Native American populations have lower genetic diversity and greater differentiation than populations from other continental regions. We observe gradients both of decreasing genetic diversity as a function of geographic distance from the Bering Strait and of decreasing genetic similarity to Siberians—signals of the southward dispersal of human populations from the northwestern tip of the Americas. We also observe evidence of: (1) a higher level of diversity and lower level of population structure in western South America compared to eastern South America, (2) a relative lack of differentiation between Mesoamerican and Andean populations, (3) a scenario in which coastal routes were easier for migrating peoples to traverse in comparison with inland routes, and (4) a partial agreement on a local scale between genetic similarity and the linguistic classification of populations. These findings offer new insights into the process of population dispersal and differentiation during the peopling of the Americas.