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. 2017 Dec 13;284(1868):20171804.
doi: 10.1098/rspb.2017.1804.

Evolutionary history of enigmatic bears in the Tibetan Plateau-Himalaya region and the identity of the yeti

Affiliations

Evolutionary history of enigmatic bears in the Tibetan Plateau-Himalaya region and the identity of the yeti

Tianying Lan et al. Proc Biol Sci. .

Abstract

Although anecdotally associated with local bears (Ursus arctos and U. thibetanus), the exact identity of 'hominid'-like creatures important to folklore and mythology in the Tibetan Plateau-Himalaya region is still surrounded by mystery. Recently, two purported yeti samples from the Himalayas showed genetic affinity with an ancient polar bear, suggesting they may be from previously unrecognized, possibly hybrid, bear species, but this preliminary finding has been under question. We conducted a comprehensive genetic survey of field-collected and museum specimens to explore their identity and ultimately infer the evolutionary history of bears in the region. Phylogenetic analyses of mitochondrial DNA sequences determined clade affinities of the purported yeti samples in this study, strongly supporting the biological basis of the yeti legend to be local, extant bears. Complete mitochondrial genomes were assembled for Himalayan brown bear (U. a. isabellinus) and black bear (U. t. laniger) for the first time. Our results demonstrate that the Himalayan brown bear is one of the first-branching clades within the brown bear lineage, while Tibetan brown bears diverged much later. The estimated times of divergence of the Tibetan Plateau and Himalayan bear lineages overlap with Middle to Late Pleistocene glaciation events, suggesting that extant bears in the region are likely descendants of populations that survived in local refugia during the Pleistocene glaciations.

Keywords: Himalaya; Tibetan Plateau; Ursus arctos; Ursus thibetanus; mitochondrial DNA; phylogenetics.

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Conflict of interest statement

The authors have no competing interests.

Figures

Figure 1.
Figure 1.
Distribution of Himalayan and Tibetan brown bear and localities of samples studied. Red and blue lines outline the approximate historical range of the Himalayan brown bear and the Tibetan brown bear, respectively (redrawn from Galbreath et al. [15]). The triangles, diamonds and circles, respectively, indicate the approximate collecting localities of the studied samples associated with Asian black bear, Tibetan brown bear and Himalayan brown bear.
Figure 2.
Figure 2.
Phylogenetic trees based on (a) ML and (b) BI analyses of new mtDNA sequence data produced in this study and sequence data obtained from GenBank. New sequences are marked with triangles, diamonds, circles and a square, indicating the Asian black bear, Tibetan brown bear, Himalayan brown bear and the brown bear from the AMNH, respectively. GenBank data include complete mitogenomes of non-Tibetan–Himalayan bears, as well as amplicon and complete mitochondrial sequences of Tibetan and Himalayan bears. Major maternal clades and their geographic range are labelled following [10,17]. See electronic supplementary material, figures S2 and S3, for complete versions of the trees, shown with posterior probability and bootstrap values.
Figure 3.
Figure 3.
Maximum clade credibility tree from a BEAST analysis based on complete mitogenomes. The numbers at nodes indicate the median estimated divergence time in ka BP (HPD values are shown in brackets and the lower scale indicates time in ka BP). The coloured vertical bars indicate, from left to right, time spans of four Pleistocene glaciations: the Xixabangma, Nyanyaxungla, Guxiang and Baiyu. New mitogenomes sequenced in this study are indicated with symbols as in figure 2. See electronic supplementary material, figure S4, for a complete version of the tree and divergence times estimated for all nodes.

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