Approximately 97% of Native American mtDNAs belong to one of four major founding mtDNA lineages, designated A to D (Haplogroup A, Haplogroup B, Haplogroup C, Haplogroup D). A fifth mtDNA haplogroup, Haplogroup X, represents a minor founding lineage in Native Americans.

 There is general agreement that the Native American founder populations migrated from Asia into America through Beringia sometime during the Pleistocene.

 Haplogroups A, B, and C form monophyletic clades, but the five haplogroup D sequences have unstable positions and usually do not group together.

 The high degree of similarity in the nucleotide diversity and time of differentiation (i.e., approximately 21,000 years before present) of these four haplogroups support a common origin for these sequences and suggest that the populations who harbor them may also have a common history.

 Age of differentiation at approximately 21,000 years before present could coincides with the process of colonization of the New World and supports the hypothesis of a single and early entry of the ancestral Asian population into the Americas.

 Four haplotype groups (Haplogroup A, Haplogroup B, Haplogroup C, and Haplogroup D) in the Amerind, but only one haplogroup (Haplogroup A) in the Na-Dene, and confirmed the independent origins of the Amerinds and the Na-Dene. (#7688932#)

 Eskimos and northern Na-Dene groups are almost exclusively mtDNA haplogroup A.

 Tribes of the Southwest and adjacent regions, predominantly Hokan and Uto-Aztecan speakers, lack Haplogroup A but exhibit high frequencies of Haplogroup B.

 Tribes of the Southwest and Mexico lacking only Haplogroup D.

 A geographically heterogeneous group of tribes which exhibit varying frequencies of all four haplogroups. There is some correspondence between language group affiliations and the frequencies of the mtDNA haplogroups in certain tribes, while geographic proximity appears responsible for the genetic similarity among other tribes.

 Each haplogroup appeared to have been founded by a single mtDNA haplotype, a result which is consistent with a hypothesized founder effect. (#7688932#)

 Most of the variation within haplogroups was tribal specific, that is, it occurred as tribal private polymorphisms. (#7688932#)

 The process of tribalization began early in the history of the Amerinds, with relatively little intertribal genetic exchange occurring subsequently. (#7688932#)

 The haplotype variation, arose predominantly after the migration of the ancestral Amerinds across the Bering land bridge. (#7688932#)

 Y-chromosome variations study (male ancestry)

• The distribution, relatedness, and diversity of Y lineages in Native Americans indicate a differentiated male ancestry for populations from North and South America, strongly supporting a diverse demographic history for populations from these areas. (#12900798#)
• Data are consistent with the occurrence of two major male migrations from southern/central Siberia to the Americas (with the second migration being restricted to North America) and a shared ancestry in central Asia for some of the initial migrants to Europe and the Americas. (#12900798#)
• The microsatellite diversity and distribution of a Y lineage specific to South America (Q-M19) indicates that certain Amerind populations have been isolated since the initial colonization of the region, suggesting an early onset for tribalization of Native Americans. (#12900798#)
• Age estimates based on Y-chromosome microsatellite diversity place the initial settlement of the American continent at approximately 14,000 years ago, in relative agreement with the age of well-established archaeological evidence. (#12900798#)

 There is very little evidence that more than five founder mtDNA sequences entered Beringia before the Last Glacial Maximum and left their traces in the current Native American mtDNA pool. (#14641239#)

Features

 single early entry (Silva WA, 2002)
 entry: age ? number ? size ?
 haplogroups A, B, C, D

 average time of entry

• HSV I : 42 000 to 29 000 years BP
• HSV-I + HSV-II : 43 000 to 33 000 years BP

References

 Salas A, Richards M, Lareu MV, Scozzari R, Coppa A, Torroni A, Macaulay V, Carracedo A. The African diaspora: mitochondrial DNA and the Atlantic slave trade. Am J Hum Genet. 2004 Mar;74(3):454-65. PMID: #14872407#

 Seielstad M, Yuldasheva N, Singh N, Underhill P, Oefner P, Shen P, Wells RS. A novel Y-chromosome variant puts an upper limit on the timing of first entry into the Americas. Am J Hum Genet. 2003 Sep;73(3):700-5. PMID: #12929085#

 Bortolini MC, Salzano FM, Thomas MG, Stuart S, Nasanen SP, Bau CH, Hutz MH, Layrisse Z, Petzl-Erler ML, Tsuneto LT, Hill K, Hurtado AM, Castro-de-Guerra D, Torres MM, Groot H, Michalski R, Nymadawa P, Bedoya G, Bradman N, Labuda D, Ruiz-Linares A. Y-chromosome evidence for differing ancient demographic histories in the Americas. Am J Hum Genet. 2003 Sep;73(3):524-39. PMID: #12900798#

 Silva WA Jr, Bonatto SL, Holanda AJ, Ribeiro-Dos-Santos AK, Paixao BM, Goldman GH, Abe-Sandes K, Rodriguez-Delfin L, Barbosa M, Paco-Larson ML, Petzl-Erler ML, Valente V, Santos SE, Zago MA. Mitochondrial genome diversity of Native Americans supports a single early entry of founder populations into America. Am J Hum Genet. 2002 Jul;71(1):187-92. PMID: #12022039#

 Bonatto SL, Salzano FM. Diversity and age of the four major mtDNA haplogroups, and their implications for the peopling of the New World. Am J Hum Genet. 1997 Dec;61(6):1413-23. PMID: #9399887#

 Lorenz JG, Smith DG. Distribution of four founding mtDNA haplogroups among Native North Americans. Am J Phys Anthropol. 1996 Nov;101(3):307-23. PMID: #8922178#

 Torroni A, Sukernik RI, Schurr TG, Starikorskaya YB, Cabell MF, Crawford MH, Comuzzie AG, Wallace DC. mtDNA variation of aboriginal Siberians reveals distinct genetic affinities with Native Americans. Am J Hum Genet. 1993 Sep;53(3):591-608. PMID: #7688933#

 Torroni A, Schurr TG, Cabell MF, Brown MD, Neel JV, Larsen M, Smith DG, Vullo CM, Wallace DC. Asian affinities and continental radiation of the four founding Native American mtDNAs. Am J Hum Genet. 1993 Sep;53(3):563-90. PMID: #7688932#