Reconciling migration models to the Americas with the variation of North American native mitogenomes.
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.
Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, 06123 Perugia, Italy. alessandro.achilli@unipg.it
Alessandro
A
Achilli
Ugo A
UA
Perego
Hovirag
H
Lancioni
Anna
A
Olivieri
Francesca
F
Gandini
Baharak
B
Hooshiar Kashani
Vincenza
V
Battaglia
Viola
V
Grugni
Norman
N
Angerhofer
Mary P
MP
Rogers
Rene J
RJ
Herrera
Scott R
SR
Woodward
Damian
D
Labuda
David Glenn
DG
Smith
Jerome S
JS
Cybulski
Ornella
O
Semino
Ripan S
RS
Malhi
Antonio
A
Torroni
D004641:Emigration and Immigration; D015894:Genome, Human; D063426:Human Migration; D006801:Humans; D007198:Indians, North American / Q000235:genetics*
Native Americans; human mtDNA