Polar bears older than biologists used to think


This video is called other Polar Bear and Cubs Emerging from Den – BBC Planet Earth.

From Science:

Nuclear Genomic Sequences Reveal that Polar Bears Are an Old and Distinct Bear Lineage

Frank Hailer1,
Verena E. Kutschera1,
Björn M. Hallström,
Denise Klassert,
Steven R. Fain,
Jennifer A. Leonard,
Ulfur Arnason,
Axel Janke

Abstract

Recent studies have shown that the polar bear matriline (mitochondrial DNA) evolved from a brown bear lineage since the late Pleistocene, potentially indicating rapid speciation and adaption to arctic conditions.

Here, we present a high-resolution data set from multiple independent loci across the nuclear genomes of a broad sample of polar, brown, and black bears.

Bayesian coalescent analyses place polar bears outside the brown bear clade and date the divergence much earlier, in the middle Pleistocene, about 600 (338 to 934) thousand years ago. This provides more time for polar bear evolution and confirms previous suggestions that polar bears carry introgressed brown bear mitochondrial DNA due to past hybridization. Our results highlight that multilocus genomic analyses are crucial for an accurate understanding of evolutionary history.

See also here.

July 2012. An analysis of newly sequenced polar bear genomes is providing important clues about the species’ evolution, suggesting that climate change and genetic exchange with brown bears helped create the polar bear as we know it today. The international study found evidence that the size of the polar bear population fluctuated with key climatic events over the past million years, growing during periods of cooling and shrinking in warmer times: here.

Will more climate change mean more pizzlies (polar bear-grizzly bear hybrids)? Here.

As climate changes, polar bears switch to polluted food: here.

Thanks to global warming polar bears now risk starvation during their wait for ice to form: here.

Shrinking Arctic sea ice has left polar bears scrambling to find food, and they’ve taken to eggs in a big way, which is bad news for many seabirds. A polar bear in the Northern Hudson Bay region can eat hundreds of seabird eggs at a sitting: here.

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