Mitochondrial variation among the aymara and the signatures of population expansion in the central Andes

Abstract

Objectives The exploitation of marine resources and intensive agriculture led to a marked population increase early in central Andean prehistory. Constant historic and prehistoric population movements also characterize this region. These features undoubtedly affected regional genetic variation, but the exact nature of these effects remains uncertain. Methods Mitochondrial DNA (mtDNA) hypervariable region I sequence variation in 61 Aymara individuals from La Paz, Bolivia, was analyzed and compared to sequences from 47 other South American populations to test hypotheses of whether increased female effective population size and gene flow influenced the mtDNA variation among central Andean populations. Results The Aymara and Quechua were genetically diverse showing evidence of population expansion and large effective population size, and a demographic expansion model fits the mtDNA variation found among central Andean populations well. Estimated migration rates and the results of AMOVA and multidimensional scaling analysis suggest that female gene flow was also an important factor, influencing genetic variation among the central Andeans as well as lowland populations from western South America. mtDNA variation in south central Andes correlated better with geographic proximity than with language, and fit a population continuity model. Conclusion The mtDNA data suggests that the central Andeans experienced population expansion, most likely because of rapid demographic expansion after introduction of intensive agriculture, but roles of female gene flow need to be further explored.

The peopling of South America and the trans-Andean gene flow of the first settlers

“…The pre-Columbian mtDNA data available follow the same pattern: B2 reaches high frequencies in the Peruvian highlands, ranging from 42% to 75% (Shinoda et al 2006;Baca et al 2012Baca et al , 2014. Ancient and contemporary data indicate a genetic continuity in the Central Andes that is compatible with a high N e and intense gene flow in this area for a long time period (8-9 ky), with limited introgression from surrounding regions (Batai and Williams 2014;Cabana et al 2014;Fehren-Schmitz et al 2017). Moreover, the observed genetic patterns in the Central Andes can be tentatively linked to the population expansions of the most relevant Andean empires: the Tiwanaku, the Wari, and more recently, the Incas (Fehren-Schmitz et al 2014).…”

Climate and demography drive 7000 years of dietary change in the Central Andes

“…Few demographic reconstructions of population for the Central Andes exist, but those that do suggest populations were relatively low and stable early in the settlement of the region, with rapid increases in size later in time, though the rates and scales of population change differ by elevation 29 , 40 , 55 . Rapid population expansion 56 and larger population sizes 57 in the region appear to correlate with the incorporation of domesticates and transition to reliance on intensive agriculture as well as decreasing climatic volatility 29 . Here we generate a proxy of the past population sizes for each individual as a quantitative measure of the relative changes over time.…”