Work

Near telomere-to-telomere genome reveals the phylogenomics and hibernation-related evolution in Tibetan brown bear (Ursus arctos pruinosus)

Year: 2026

Type: article

Abstract: Background The Tibetan brown bear ( Ursus arctos pruinosus ) is an apex predator endemic to the Qinghai-Xizang Plateau (QXP) with crucial ecological status, while high-quality genomic resources for studying its plateau-adaptated evolution remain scarce. Results Here, we generated a chromosome-level genome assembly of a female Tibetan brown bear from QXP, using PacBio HiFi and Hi-C sequencing. The final assembly spans 2.42 Gb, with scaffold N50 of 72.35 Mb, contig N50 of 66.56 Mb and GC content of 42.36%. Comparative genomic analyses revealed high chromosomal synteny between Tibetan brown bear and polar bear. Demographic reconstruction of Tibetan brown bear demonstrated an population expansion during the early Pleistocene, followed by two significant population bottlenecks at approximately 2 Mya (pre-Poyang Glaciation) and 0.1 Mya (the Last Glacial Period), leading to a cumulative effective population size reduce of nearly 80%. Notably, Tibetan brown bear hibernation-related pathway analyses revealed a specific carbohydrate-dominated metabolic strategy that differs strikingly from the lipid metabolism-dependent hibernation pattern of North American brown bear. This distinct metabolic adaptation highlights its unique adaptive mechanisms for surviving extreme QXP environments. Conclusion This high-quality genome assembly provides a valuable genomic resource for exploring the evolutionary history of ursidae and facilitates future conservation and management.

Source: BMC Genomics

DOI: 10.1186/s12864-026-13324-3