Reconciling migration models to the Americas with the variation of North American native mitogenomes

Abstract

In this study we evaluated migration models to the Americas by using the information contained in native mitochondrial genomes (mitogenomes) from North America. Molecular and phylogeographic analyses of B2a mitogenomes, which are absent in Eskimo–Aleut and northern Na-Dene speakers, revealed that this haplogroup arose in North America ∼11–13 ka from one of the founder Paleo-Indian B2 mitogenomes. In contrast, haplogroup A2a, which is typical of Eskimo–Aleuts and Na-Dene, but also present in the easternmost Siberian groups, originated only 4–7 ka in Alaska, led to the first Paleo-Eskimo settlement of northern Canada and Greenland, and contributed to the formation of the Na-Dene gene pool. However, mitogenomes also show that Amerindians from northern North America, without any distinction between Na-Dene and non–Na-Dene, were heavily affected by an additional and distinctive Beringian genetic input. In conclusion, most mtDNA variation (along the double-continent) stems from the first wave from Beringia, which followed the Pacific coastal route. This was accompanied or followed by a second inland migratory event, marked by haplogroups X2a and C4c, which affected all Amerindian groups of Northern North America. Much later, the ancestral A2a carriers spread from Alaska, undertaking both a westward migration to Asia and an eastward expansion into the circumpolar regions of Canada. Thus, the first American founders left the greatest genetic mark but the original maternal makeup of North American Natives was subsequently reshaped by additional streams of gene flow and local population dynamics, making a three-wave view too simplistic.

Spatiotemporal distribution of Holocene populations in North America

“…This predates the Independence I (35) and Early Pre-Dorset (36) occupations by several thousand years and may be due to known dating problems from Arctic sites (37) and temporal smoothing of the maps. However, these dates support recent genetic evidence suggesting there was human activity in the general region around 6,000 y ago (38). By 4 ka, there are signs of occupation across the entire Canadian Arctic, and at 2.5 ka, site density increases to the south.…”

Mitochondrial genome diversity at the Bering Strait area highlights prehistoric human migrations from Siberia to northern North America

“…6 However, this model has not been fully evaluated, in part, because researchers were unable to date their arrival, which instead could be inferred from entire mitochondrial genomes. 7 The last inhabitants of former Beringia, reflected genetically in the Yukaghir, Chukchi, Eskimo-Aleuts, Na-Dene, and Northwestern North American Indians, have been a focus of extensive comparisons between complete mtDNA sequences from Siberia and from North America. As a result, the Siberian affinities of major Native American mtDNA haploclusters (A-D), initially detected by comparing a few single-nucleotide polymorphisms of similar haplotypes from Eurasia and the Americas, [7][8][9][10][11][12][13][14] have been revised and extended.…”

“…7 The last inhabitants of former Beringia, reflected genetically in the Yukaghir, Chukchi, Eskimo-Aleuts, Na-Dene, and Northwestern North American Indians, have been a focus of extensive comparisons between complete mtDNA sequences from Siberia and from North America. As a result, the Siberian affinities of major Native American mtDNA haploclusters (A-D), initially detected by comparing a few single-nucleotide polymorphisms of similar haplotypes from Eurasia and the Americas, [7][8][9][10][11][12][13][14] have been revised and extended. It has become evident that the range of distinct lineages confined to the entire Eskimo Arctic is a subset of haplogroups A2a, A2b, D2a, and D4b1a2a1, though each of their evolutionary histories is far from being explicitly clear.…”

Bison phylogeography constrains dispersal and viability of the Ice Free Corridor in western Canada

“…The Clovis First model lost favor as sites south of the LGM ice sheets, such as Monte Verde (Chile), the Gault locality (Texas), Manis (Washington), and Paisley (Oregon), provided archaeological evidence that humans were present in the Americas at least a millennium before the appearance of Clovis technology (13). At the same time, genetic analyses suggested that New World founding populations began dispersing from Beringia ∼15,000-20,000 cal y BP (14)(15)(16).…”