FOUNDER MITOCHONDRIAL HAPLOTYPES IN AMERINDIAN POPULATION

It has been proposed that the colonization of the New World took place by three successive migrations from northeastern Asia. The first one gave rise to Amerindians (Paleo-Indians), the second and third ones to Nadene and Aleut-Eskimo, respectively. Variation in mtDNA has been us ed to infer the demographic structure of the Amerindian ancestors. The study of RFLP all along the mtDNA and the analysis of nucleotide subs titutions in the D-loop region of the mitochondrial genome apparently indicate that most or all full-blooded Amerindians cluster in one of f our different mitochondrial haplotypes that are considered to represen t the founder maternal lineages of Paleo-Indians. We have studied the mtDNA diversity in 109 Amerindians belonging to 3 different tribes, an d we have reanalyzed the published data on 482 individuals from 18 oth er tribes. Our study confirms the existence of four major Amerindian h aplotypes. However, we also found evidence supporting the existence of several other potential founder haplotypes or haplotype subsets in ad dition to the four ancestral lineages reported. Confirmation of a rela tively high number of founder haplotypes would indicate that early mig ration into America was not accompanied by a severe genetic bottleneck .