How strong was the bottleneck associated to the peopling of the Americas? New insights from multilocus sequence data

Abstract

In spite of many genetic studies that contributed for a deep knowledge about the peopling of the Americas, no consensus has emerged about important parameters such as the effective size of the Native Americans founder population. Previous estimates based on genomic datasets may have been biased by the use of admixed individuals from Latino populations, while other recent studies using samples from Native American individuals relied on approximated analytical approaches. In this study we use resequencing data for nine independent regions in a set of Native American and Siberian individuals and a full-likelihood approach based on isolation-with-migration scenarios accounting for recent flow between Asian and Native American populations. Our results suggest that, in agreement with previous studies, the effective size of the Native American population was small, most likely in the order of a few hundred individuals, with point estimates close to 250 individuals, even though credible intervals include a number as large as ~4,000 individuals. Recognizing the size of the genetic bottleneck during the peopling of the Americas is important for determining the extent of genetic markers needed to characterize Native American populations in genome-wide studies and to evaluate the adaptive potential of genetic variants in this population.

An Oceanographic Perspective on Early Human Migrations to the Americas

“…Several recent papers have addressed archaeological and genetic evidence of early coastal migrations. The timings of the initial migrations into the Americas are supported by evidence of early settlement (e.g., Monte Verde South America by ~14,500 yr BP), after a moderate genetic bottleneck in Beringia about 23,000-19,000 yr BP followed by a rapid population expansion between 18,000 yr BP and 15,000 yr BP (Fagundes et al, 2008(Fagundes et al, , 2018Moreno-Mayar et al, 2018;Braje et al, 2019). This strong population expansion, which ended ~15,000 yr BP, supports pre-Clovis occupation of the New World and suggests rapid settlement of North and South America by humans following a Pacific coastal route.…”

Consequences of diverse evolutionary processes on american genetic gradients of modern humans

“…Some parameters related to the evolution of modern humans (i.e., generation time and growth rate) followed previous works based on Eurasian populations (Alves et al 2016;Arenas et al 2013;François et al 2010;Pimenta et al 2017), although we increased the migration rate to simulate a colonization of the Americas rapid enough to fit with the current knowledge (details for all the applied parameters are shown in Supplementary Material). Indeed, the population size at the onset of the colonization of the Americas followed previous works based on American populations (Fagundes et al 2018;Gravel et al 2013;Hey 2005;Kitchen et al 2008;Mulligan et al 2004…”

Initial Human Colonization of the Americas, Redux

“…Estimates of the "effective" size of the founding population, based on their descendants' genetic diversity, have ranged from a low of about 43 (Ray et al 2010) to a high of about 5400 (Kitchen et al 2008). Most recently, Fagundes et al (2018) estimated the founding population as about 230-300, with a 95% credible interval between about 100 and 3700 individuals. Effective population sizes, by analogy with recent Polar Eskimo, are probably about 60% of the census population (Matsumura and Forster 2008).…”