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Abstract Background The modern wildherd of the tundra muskox (Ovibos moschatus) is native only to the New World (northern North America and Greenland), and its genetic diversity is notably low. However, like several other megafaunal mammals, muskoxen enjoyed a holarctic distribution during the late Pleistocene. To investigate whether collapse in range and loss of diversity might be correlated, we collected mitochondrial sequence data (hypervariable region and cytochrome b) from muskox fossil material recovered from localities in northeastern Asia and the Arctic Archipelago of northern North America, dating from late Pleistocene to late Holocene, and compared our results to existing databases for modern muskoxen. Results Two classes of haplotypes were detected in the fossil material. "Surviving haplotypes" (SHs), closely similar or identical to haplotypes found in modern muskoxen and ranging in age from ~22,000 to ~160 yrbp, were found in all New World samples as well as some samples from northeastern Asia. "Extinct haplotypes" (EHs), dating between ~44,000 and ~18,000 yrbp, were found only in material from the Taimyr Peninsula and New Siberian Islands in northeastern Asia. EHs were not found in the Holocene muskoxen specimens available for this study, nor have they been found in other studies of extant muskox populations. Conclusion We provisionally interpret this evidence as showing that genetic variability was reduced in muskoxen after the Last Glacial Maximum but before the mid-Holocene, or roughly within the interval 18,000-4,000 yrbp. Narrowing this gap further will require the recovery of more fossils and additional genetic information from this interval.

Arnold, L. J., Roberts, R. G., MacPhee, R. D. E., Haile, J. S., Brock, F., Möller, P., Froese, D. G., Tikhonov, A. N., Chivas, A. R., Gilbert, M. T. P. & Willerslev, E. 2010: Paper II - Dirt, dates and DNA: OSL and radiocarbon chronologies of perennially frozen sediments in Siberia, and their implications for sedimentary ancient DNA studies. Boreas, Vol. 40, pp. 417-445. 10.1111/j.1502-3885.2010.00181.x. ISSN 0300-9483 The sedimentary ancient DNA ( sedaDNA) technique offers a potentially invaluable means of investigating species evolution and extinction dynamics in high-latitude environments. An implicit assumption of the sedaDNA approach is that the extracted DNA is autochthonous with the host deposit and that it has not been physically transported from older source deposits or reworked within the sedimentary profile by postdepositional mixing. In this paper we investigate whether these fundamental conditions are upheld at seven perennially frozen wetland sites across the Taimyr Peninsula and coastal lowlands of north-central Siberia. Optically stimulated luminescence (OSL) and radiocarbon (C) dating are used to constrain the ages of both the inorganic and organic fractions of perennially frozen deposits from which sedaDNA of extinct and extant species have been recovered. OSL and C age/depth profiles, as well as single-grain equivalent dose (D) distribution characteristics, are used to assess the stratigraphic integrity of these sedaDNA sequences by (i) identifying the presence of primary or reworked organic and inorganic material, and (ii) examining the types of depositional and postdepositional processes that have affected specific sedimentary facies. The results of this study demonstrate that even though DNA preservation and stratigraphic integrity are commonly superior in perennially frozen settings, this does not, in itself, guarantee the suitability of the sedaDNA approach. The combined OSL and C chronologies reveal that certain perennially frozen sites may be poorly suited for sedaDNA analysis, and that careful site selection is paramount to ensuring the accuracy of any sedaDNA study - particularly for 'latest appearance date' estimates of extinct taxa. [ABSTRACT FROM AUTHOR]

The brown bear (Ursus arctos L., 1758) is a widespread bear species inhabiting the forest zone of Eurasia, including the Republic of Yakutia. The association with forest habitats explains why the Pleistocene findings of U. arctos fossils are rare in the northern part of Eastern Siberia, where open steppe-tundra and steppefied landscapes prevailed during the Pleistocene. Fossils of U. arctos that have been found on the territory of Yakutia are dated since the beginning of the Middle Pleistocene. These are mainly the skulls and bones of the postcranial skeleton. In the present study, using comparative morphological analysis, computed tomography, and DNA sequencing, we describe a first mummified carcass of a brown bear individual that inhabited the New Siberian Islands (Northeast Siberia) in the Middle Holocene, approximately 3,500 years BP, which was found in the permafrost of Bolshoy Lyakhovsky Island, Russia, in 2020. [ABSTRACT FROM AUTHOR]