Monday, January 10, 2011

Origin and Post-Glacial Dispersal of Mitochondrial DNA Haplogroups C and D in Northern Asia

Ancient Beringia Area


The territory of northern Asia is of crucial importance for the study of early human dispersal and the peopling of the Americas. Recent findings about the peopling of northern Asia reconstructed by archaeologists suggest that modern humans colonized the southern part of Siberia around 40 thousand years ago (kya) and the far northern parts of Siberia and ancient Beringia prerequisite for colonization of the Americasby approximately 30 kya [1][2]. Current molecular genetic evidence suggest that the initial founders of the Americas emerged from an ancestral population of less than 5000 individuals that evolved in isolationlikely in Beringiafrom where they dispersed south after approximately 17 kya [3]–[6]. The genetic data have not revealed multiple late-Pleistocene migrationsbut do distinguish a Holocene dispersal of Eskimo-Aleuts from northeastern Asia as well as detect two distinct almost concomitant paths for the Paleo-Indian dispersal from Beringia approximately 15–17 kya [7]. Additionallythe first successful genome sequencing of a 4000-year-old Greenland individual belonging to the Saqqaq Culture has provided an unambiguously evidence for a close relationship between Saqqaq and Siberian Arctic populations and for migration from Siberia into the New World some 5.5 kya independent of that giving rise to the modern Native Americans and Inuit [8].
Notably most of genetic evidence concerning the peopling of Americas has been acquired from the analysis of the mtDNA haplogroups at the highest level of molecular resolution – that of complete mtDNA sequences [4]–[7][9]–[12]. A comprehensive overview of all available complete mtDNA genomes has allowed reconstruction of the detailed phylogeny of the six Native American haplogroups (A2B2C1D1X2aand D4h3)identification of their internal clades and candidate founder sequencesand estimation of their expansion times into the Americas [5][7][9].
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