Why Don’t Polar Bears Hibernate?

The polar bear’s coat helps it blend in with its snow-covered environment, which is a useful hunting adaptation. The polar bear’s front legs appear slightly bowllegged and pigeon-toed, and fur covers the bottoms of its paws. These adaptations help the polar bear keep them from slipping on ice. Photo taken by Charles Welch 2014

The polar bear’s coat helps it blend in with its snow-covered environment, which is a useful hunting adaptation. The polar bear’s front legs appear slightly bowllegged and pigeon-toed, and fur covers the bottoms of its paws. These adaptations help the polar bear keep them from slipping on ice. Photo taken by Charles Welch 2014

Every elementary school student is taught the misconception that all bears hibernate for the winter. However, for polar bears, winter is their hunting season.

A research team at the University of Buffalo, led by Charlotte Lindqvist, found that gene adaptations in polar bears allow them to convert nutrients into heat in colder temperatures.

Polar bear eating habits differ from most other bear species in that they fast most of the summer and overeat throughout the winter whether food is available or not.

The new study found that genes controlling nitric oxide, a compound used to convert food into heat, contain differences from comparable genes in brown and black bears. The genes in polar bears proved to be more active and enhanced.  More unique variations of the genes were also found in the polar bears.  Twenty three polar bears, three brown bears and one black bear were used in the study.  The scientists investigated the genomes of these 27 bears.

Normally, nutrients is converted into energy but in this case adaptive thermogenesis occurs meaning energy is produced in the form of heat.  This happens due to a particular environmental condition; in this case extreme cold.

“Levels of nitric oxide production may be a key switch triggering how much heat or energy is produced as cells metabolize nutrients, or how much of the nutrients is stored as fat”, Lindqvist said.

Scientists are using this research to look at polar bear response to climate change and the melting of the ice caps.  This research is also being used to make sense of how polar bears can thrive in such a harsh climate.

For more information visit:

http://www.polarbearsinternational.org/news-room/news/how-do-polar-bears-stay-warm-research-finds-answer-their-genes

Journal Source:

Andreanna J. Welch, Oscar C. Bedoya-Reina, Lorenzo Carretero-Paulet, Webb Miller, Karyn D. Rode, Charlotte Lindqvist. (2014). Polar Bears Exhibit Genome-Wide Signatures of Bioenergetic Adaptation to Life in the Arctic Environment. Genome Biol Evol (2014)doi: 10.1093/gbe/evu025

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