GENETIC EVIDENCE FOR THE COLLAPSE AND TRANSIENT RECOVERY OF MUSKOX (OVIBOS) IN LATE QUATERNARY TAIMYR, SIBERIA

The existing standing crop of Ovibos is naturally distributed only in the New World (NW), although muskoxen formerly lived in Eurasia (OW) as well. What is the relationship of OW and NW muskoxen, and what happened to OW Ovibos? It is well known that extant Ovibos moschatus displays little genetic diversity (8 haplotypes recovered from 37 samples by Groves et al. [1997]). Among-haplotype diversity (AHD) is also low (1-7 differences). To create a comparable dataset for extinct OW Ovibos, using ancient DNA techniques (Greenwood et al., 2001) we successfully characterized the mitochondrial control region in 6 dated fossil samples from Taimyr, Siberia, ranging in age from ca. 22,000 BP to 2900 BP. In late Pleistocene Taimyr (LPT) specimens, we found 4 haplotypes (AHD, 5-7 differences). Unexpectedly, LPT samples differed from all NW muskoxen to a marked degree (13-23 positions). According to the ¹⁴C record, there is no empirical evidence for the presence of muskoxen in Eurasia between ca. 10,000 and 4000 BP. According to the same record, ca. 4000 BP muskoxen made a brief reappearance (in Taimyr only?) before finally disappearing completely well before 2000 BP. Partial sequence for our youngest mid-Holocene Taimyr (MHT) specimen yielded 2-6 differences from modern NW muskoxen haplotypes for the same region. Incomplete data for Pleistocene Alaskan muskoxen are similar. By contrast, LPT muskoxen displayed 8-11 differences for the same region, and there were 5-6 differences between LPT and MHT samples. Preliminary phylogenetic analysis shows that NW and MHT muskoxen group separately from LPT muskoxen (which may indicate that Pleistocene Eurasian muskox should be regarded as a distinct species). Accordingly, existing data are consistent with the following scenario: (1) In OW, endemic Pleistocene muskox lineages became extinct, presumably at the end of the epoch. (2) During the mid-Holocene, at least one part of Asia was briefly recolonized by a lineage related to the NW population, which had itself passed through a severe genetic bottleneck. On a wider scale, the vicissitudes suffered by Ovibos suggests that the agent(s) that forced the end-Pleistocene extinctions may have had a severe (and heretofore unmeasured) impact on many megafauna, not just the species that became completely extinct (e.g., woolly mammoth, woolly rhino).