| MadSci Network: Genetics |
I looked in the web for mtDNA and native Americans and came up with several web sites. The most interesting and relevant one to your question is the following paper presented at the INTERNATIONAL SYMPOSIUM: The Origin of Humankind Venezia, Palazzo Loredan in May 1998. Global Mitochondrial DNA Variation and the Origin of Native Americans Douglas C. Wallace, Michael D. Brown, Theodore G. Schurr, Estella Chen, Yu-Sheng Chen, Yelena B. Starikovskaya and Rem I. Sukernik. Center for Molecular Medicine Emory University Medical School Atlanta, GA 30322 The complete sequence of 39 mitochondrial DNAs (mtDNAs) have confirmed that all human mtDNAs form a single phylogenetic tree, the mtDNAs from each continent (Europe, Asia and Africa) cluster together, and African mtDNAs are the most divergent, hence the oldest, followed by Asian and then European mtDNAs. Comparison with chimpanzee mtDNA roots the human mtDNA tree in Africa and gives an estimated coalescence time of 149,000 years before present (YBP), with 95% confidence limits of 81,000-231,000 YBP. Surveys of continent-specific mtDNA variation using restriction site polymorphisms (RSPs) and control region (CR) sequences have extended this analysis. Using RSP data, the overall sequence diversity of African mtDNAs has been estimated at 0.369%, giving an estimated coalescence time of between 130,000 and 170,000 YBP. Phylogenetic analysis of African mtDNA RSPs has revealed that approximately two thirds of African mtDNAs belong to a group of related mtDNA haplotypes, designated macro-haplogroup L, defined by the presence of a Hpal site ar nucleotide pair (np) 3592. The remaining African mtDNAs divide into four haplogroups which are more similar to European and Asian mtDNAs, than to those of macro-haplogroup L. Macro-haplogroup L is subdivided into haplogroups L1 and L2, and, vithin these haplogroups, distinct lineages are observed for the !Kung, Western Pygmy, Eastern Pygmy, and Senegalese. Phylogenetic and sequence divergence estimates indicate that the !Kung and Western Pygmys are the oldest African populations and that the Eastern and Western Pygmys had independent origins. Analysis of European mtDNA variation has revealed that 99% of European mtDNAs fall into nine haplogroups (H, I, J, K T, U, V, W, and X). The European mtDNA coalescence time is between 40,000 and 50,000 YBP. Central Asian mtDNAs generally fall into two macro-haplogroups. About 55% of Asian mtDNAs harbor two linked RSPs, a DdeI site at np 10394 and an AluI site at np 10397; while almost all of the remainder of Asian mtDNAs lack these sites. Asian mtDNAs which lack the 10394/10397 sites are subdivided into a number of haplogroups, including "A" which is defined by a HaeIII site gain at np 663 and "B" which is defined bu a 9 np COII-tRNALys intergenic deletion. Asian mtDNAs harboring the 10394/10397 sites are also subdivided into haplogroups including haplogroup "C" defined by a combined HincII site loss at np 13259 and AluI site gain at np 13262; and "D" defined by an AluI site loss at np 5176. The coalescence time for the Asian 10394/10397 lineage is about 56 to 73,000 YBP. Analysis of Native American mtDNAs revealed that mosto fall into four major haplogroups (A, B, C and D). Each of these haplogroups encompasses a coherent lineage of Native American specific mtDNA haplotypes which trace back to a founding haplotype that is also present in Asia. This implies that Native Americans were founded by a limited number of Asian ancestors. Analysis of the distribution of haplogroups A, B, C, and D among Native Americans revealed that the Amerind speaking Paleo-Indians of North, Central, and South America harbor all four haplogroups; the Na-Dene speakers of the Pacific Northwest as well as the Navajo and Apache of the Southwest harbor predominantly A; and the Eskimos and Aleuts harbor haplogroups A and D. This suggests that each of these groups of populations is genetically distinct. The coalescence time for Amerind haplogroups A, C, and D is about 20,000 to 30,000 YBP, suggesting that the first Americans arrived in the New World prior to the emergence of the Clovis lithic culture. Haplogroup B may have arrived independently and mixed with the populations carrying haplogroups A, C, and D. By contrast, the coalescence time of Na-Dene haplogroup A suggests that this population radiated into the Americans about 7 to 9,000 YBP. In addition to the primary Native American haplogroups, we have also identified a rare fifth haplogroup "X" in the northern Amerinds and the Navajo. This haplogroup is defined by the absence of a DdeI site at np 1715, the presence of an AccI site at np 14465, and several CR variants. Interestingly, distantly related haplogroup X mtDNAs have been found in Europe, but have not been detected in Asia. The coalescence a time of haplogroup X in the Americas is between 12 and 36,000 YBP, suggesting it represents a distinct migration to the New World. MtDNA analysis of aboriginal Siberian populations has revealed that haplogroups C and D are widely distributed throughout Siberia, while haplogroup B is virtually absent. Haplogroup A is present at relatively low frequencies throughout Siberia, but increases to 68% in the Chukchi of the Chokotka peninsula adjacent to Alaska. Haplogroups C (11%), D (12%), and G (9%) are also found in the Chukchi. The neighboring Koryaks of the Kamchatka peninsula have 4% A, 37% C, 11% D, 43% G, 10% Y and 4%Z. Hence, the haplogroup distribution of the Chukchi most closely resembles that of Native Americans. Analyses of the haplogroup A CR sequence variation in populations surrounding the Bering Strait has indicated that ancient Beringian populations also expanded into northern North America after the last major glacial period. The ancestral Beringian population is delineated by the CR np 16111 T polymorphism which gave rise to all Native American groups. The later Beringian populations are defined by a subsequent polymorphism at np 16192 T which is found in the haplogroup A mt DNA of modern Koyaks, Chukchi, Siberian and Alaskan Eskimos and Na-Dene Indians. In summary, modern Native American population have been derived from at least two and possibily three expansions out of northeastern Asia, the first occurring about 20,000 to 30,000 YBP. hope this helps, gabriel vargas md/phd
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