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.
Highlights
The Tibetan Plateau, the most extensive and highest plateau in the world with an average altitude of 4500 m above sea level, is partly surrounded by the Himalayan range and many of Earth’s highest mountains
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
Summary
The Tibetan Plateau, the most extensive and highest plateau in the world with an average altitude of 4500 m above sea level, is partly surrounded by the Himalayan range and many of Earth’s highest mountains. Based on a short fragment of the mtDNA 12S rRNA gene from two samples collected in Ladakh, India and Bhutan, respectively, and a 100% match to a sequence recovered from a subfossil polar bear [38], Sykes et al [37] speculated that an unclassified bear species or hybrid of polar bear and brown bear might be present in the Tibetan Plateau–Himalaya region. We report on new analyses of 24 field-collected and museum specimens, including hair, bone, skin and faecal samples, collected from bears or purported yetis in the Tibetan Plateau–Himalaya region Based on both amplified mtDNA loci as well as complete mitogenomes, we reconstructed maternal phylogenies to increase knowledge about the phylogenetic relationships and evolutionary history of Himalayan and Tibetan bears. Effective sampling size value greater than 200 for all parameters sampled from the MCMC and the posterior distributions were examined using Tracer v. 1.6 [60]
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