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Mitochondrial Population Genomics Supports a Single Pre-Clovis Origin with a Coastal Route for the Peopling of the Americas

Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, RS, 91619-900, Brazil.
The American Journal of Human Genetics (Impact Factor: 10.99). 04/2008; 82(3):583-92. DOI: 10.1016/j.ajhg.2007.11.013
Source: PubMed

ABSTRACT It is well accepted that the Americas were the last continents reached by modern humans, most likely through Beringia. However, the precise time and mode of the colonization of the New World remain hotly disputed issues. Native American populations exhibit almost exclusively five mitochondrial DNA (mtDNA) haplogroups (A-D and X). Haplogroups A-D are also frequent in Asia, suggesting a northeastern Asian origin of these lineages. However, the differential pattern of distribution and frequency of haplogroup X led some to suggest that it may represent an independent migration to the Americas. Here we show, by using 86 complete mitochondrial genomes, that all Native American haplogroups, including haplogroup X, were part of a single founding population, thereby refuting multiple-migration models. A detailed demographic history of the mtDNA sequences estimated with a Bayesian coalescent method indicates a complex model for the peopling of the Americas, in which the initial differentiation from Asian populations ended with a moderate bottleneck in Beringia during the last glacial maximum (LGM), around approximately 23,000 to approximately 19,000 years ago. Toward the end of the LGM, a strong population expansion started approximately 18,000 and finished approximately 15,000 years ago. These results support a pre-Clovis occupation of the New World, suggesting a rapid settlement of the continent along a Pacific coastal route.

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Available from: Ândrea Ribeiro dos Santos, Jul 29, 2015
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    • "After decades of intense research, the subject of the settlement of the New World continues to be highly controversial . Although it is widely recognized that America was the last continent to be populated, probably from Asia through Beringia during the last glaciations at the end of the Pleistocene, researchers' views on various aspects of this process (e.g., from where, by whom, how many times the continent has been populated) differ significantly (Lahr, 1996; Bonatto and Salzano, 1997; Santos et al., 1999; Tarazona-Santos and Santos, 2002; Bortolini et al., 2003; Schurr, 2004; Neves and Hubbe, 2005; Goebel et al., 2003; Fagundes et al., 2008; Gonz alez-Jos e et al., 2008; Marangoni et al., 2013; Raghavan et al., 2014a, 2014b, Rasmussen et al. 2014; Dixon 2013, among others). This is probably due to the fact that insights into the peopling of the Americas comes from a variety of disciplines including geology, paleoecology, archaeology, skeletal biology, and genetics, yet the models that intend to explain such different lines of evidence are often centered on only one specific data type, sometimes disregarding potentially complementary interpretations of other traits. "
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    • "Evidence from mitochondrial DNA obtained from people with native American roots and ancient DNA retrieved from pre-Columbian human remains suggests that the Americas became populated by a comparatively homogenous group of people with common ancestors from Eastern Siberia (Eshleman, Malhi, & Smith, 2003; Greenberg, Turner, & Zegura, 1986). One study even suggests that the entire pre-Columbian American population may have derived from as few as 80 founding individuals (Fagundes et al., 2008, p. 584). Although most scholars believe that the continental migration went exclusively via Beringia and not via the Polynesian islands into South America, it is unclear whether this happened by foot or by boat. "
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    • "Importantly, sequencing the hypervariable region alone captures a lot of diversity in a short stretch of sequence, but does not provide a full picture of mitogenome diversity. As demonstrated by SOM Table 1, multiple dog haplotypes have identical sequences in the region we studied, so it is possible that we are underestimating the diversity of dog mitogenomes present in the Americas, as was found true of human mitochondrial diversity as mitogenome sequencing became more routine (Tamm et al., 2007; Achilli et al., 2008; Fagundes et al., 2008). This underestimation, combined with the possibility of breeding practices mentioned above, may mean that some of the putative founding haplotypes we have identified are not as frequent or as widespread as our results seem to indicate. "
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