New ancient DNA sequences suggest high genetic diversity for the woolly mammoth (Mammuthus primigenius)

Partial DNA sequences of cytochrome b gene (mtDNA) were successfully retrieved from I-ate Pleistocene fossil bone of Mammuthus primigenius collected from the Xiguitu County (Yakeshi), Inner Mongolia Autonomous Region and from Zhaodong, Harbin of Heilongjiang Province in northern China. Two ancient DNA fragments (109 bp and 124 bp) were authenticated by reproducible experiments in two different laboratories and by phylogenctic analysis with other Elephantidae taxa. Phylogenetic analysis using these sequences and published data in either separate or combined datasets indicate unstable relationship among the woolly mammoth and the two living elephants, Elephas and Loxodonta. In addition to the short sequences used to attempt the long independent evolution of Elephantidae terminal taxa, we suggest that a high intra-specific diversity existed in Mammuthus primigenius crossing both spatial and temporal ranges, resulting in a complex and divergent genetic background for DNA sequences so far recovered. The high genetic diversity in the extinct woolly mammoth can explain the apparent instability of Elephantidae taxa on the molecular phylogenctic trees and can reconcile the apparent paradox regarding the unresolved Elephantidae trichotomy.