mtDNA Variation in the Altai-Kizhi Population of Southern Siberia: A Synthesis of Genetic Variation

Human Biology, Aug 2006 by Phillips-Krawczak, Christine, Devor, Eric, Zlojutro, Mark, Moffat-Wilson, Kristin, Crawford, Michael H

Despite the differences between the Altai samples, the coalescent dates are similar. Even though these coalescent dates are not specific to the Altai region but are more a reflection of the initial colonization and expansion into the Eurasian landmass, their similarity is reassuring because it is unlikely that inadequate sampling will disrupt the deep interior branches of the Altai's actual mtDNA structure.

The importance of the Altaian region is evident when addressing the peopling of the New World. The five founding haplogroups, A, B, C, D, and X, found in Native American populations are also present in the Altai (Starikovskaya et al. 2005), suggesting that the Altaian population is a likely ancestral population to Native Americans. It should be noted that the Native American haplogroup X is a specific subhaplotype (X2a) not presently found outside the New World (Reidla et al. 2003). The Altaian haplogroup X has been postulated to hold an intermediate position between European and Native American haplogroup X lineages (Derenko et al. 2001b). Alternative theories suggest that the haplogroup X mtDNAs found in the Altai are not related to the Native American lineages and are explained by recent gene flow from Europe or West Asia into the Altai region (Reidla et al. 2003). Because Native American haplogroup X sequences have been designated as a subgroup that is phylogenetically distinctive from Eurasian haplogroup X, the ancestral origin of this Native American lineage remains unresolved.

In summary, Mendur-Sokkon exhibits depressed θ estimates and gene diversity scores relative to other Altai samples, which demonstrates MendurSokkon's similarity to some neighboring south Siberian populations and may suggest the effects of a population bottleneck, perhaps a genetic signature of Russian contact and the corresponding decline in native Siberian population numbers (Forsyth 1992). The Derenko et al. (2003) Altai mtDNA data, on the other hand, are more consistent with the statistics of groups with known histories of expansion, such as the Mongols, and likely represent an artifact of the sampling strategy, which involved greater geographic coverage of the Altai region. Thus independent sampling of a single population can result in a different picture of a population's evolutionary history.

Acknowledgments We thank the members of the research team from the Siberian Branch of the Academy of Sciences who were instrumental in the collection of the blood samples from the study participants. In particular, we thank L. Osipova, T. Karafet, and O. Posukh; without their help this study would not have been possible. We are most thankful to the villagers of Mendur-Sokkon for their assistance and hospitality. We also extend our gratitude to Theodore Schurr for his expertise and use of his laboratory during the commencement of these mtDNA analyses. This project was supported by a General Research Grant from the University of Kansas and by the Siberian Branch of the Russian Academy of Sciences.