Polar and brown bear genomes reveal ancient admixture and demographic footprints of past climate change.

ABSTRACT: Polar bears (PBs) are superbly adapted to the extreme Arctic environment and have become emblematic of the threat to biodiversity from global climate change. Their divergence from the lower-latitude brown bear provides a textbook example of rapid evolution of distinct phenotypes. However, limited mitochondrial and nuclear DNA evidence conflicts in the timing of PB origin as well as placement of the species within versus sister to the brown bear lineage. We gathered extensive genomic sequence data from contemporary polar, brown, and American black bear samples, in addition to a 130,000- to 110,000-y old PB, to examine this problem from a genome-wide perspective. Nuclear DNA markers reflect a species tree consistent with expectation, showing polar and brown bears to be sister species. Howeve

SUBMITTER: Miller W 

PROVIDER: S-EPMC3437856 | biostudies-literature | 2012 Sep

REPOSITORIES: biostudies-literature