Thursday, December 16, 2010

Wild Polar Bears Under Threat of Hybridization with Grizzly Bears

A possible grizzly/polar bear hybrid

A recent study has shown that the rapid loss of sea ice in the Arctic is leading to a formation of hybrids between polar bears and grizzly bears. Scientists believe that the reduction of an area covered by floating sea ice is forcing the polar bear to come into contact with its forest-dwelling relative, which could threaten the gene pool between the two distinctive species. The first polar-grizzly hybrid spotted in the wild was in 2006. In appearance, the creature was white with brown patches. DNA tests confirmed that it was a result of hybridization between the two species. The most recent sighting was earlier this year when a hybrid was killed by hunter in the western Canadian Arctic, and tests showed that it was a second-generation hybrid. That is, its parents were a hybrid female and a pure-bred male grizzly bear.

Scientists also believe that there are probably more cases of these bizarre hybrids out there because of change in behavior of polar bears brought by climate change. They would spend more time on shore waiting for ice to form, in turn bringing them into close contact with grizzlies. One study led by Dr. Brendan Kelly of Juneau's U.S National Marine Mammal Laboratory discovered 34 possible hybridizations, out of which 22 cases involved isolated population at risk of intermixing. According to Dr. Kelly and his colleagues, it is predicted that the Arctic Ocean will loose its ice in summer before the end of the century, removing a vast icy barrier and leading to interbreeding between the two bears. Furthermore, scientists say that the extent of this hybridization could have major implications on polar bears. For example, zoologists in a German zoo had found that polar-grizzly bear hybrids lack strong swimming abilities associated with polar bears which they use when roaming vast stretches of the Arctic during winter months to hunt seals. Also, Dr. Andrew Whiteley of the University of Massachusetts stated that hybridization can cause loss of biodiversity in which distinct lineages that have evolved over millenia become mixed.

This report, in my opinion, sends a clear message of why we should join together to fight global warming. The melting polar ice caps are forcing the polar bears further inland where they are usually never be found. This has been leading to them to come into contact with their distant relatives, grizzly bears, and resulting in hybrids. Normally, hybrids like these would be seen in captivity. Seeing a polar-grizzly bear hybrid out in the wild is like seeing a liger which is also seen in captivity. Although these creations are natural features of the evolution, they do tend to not have certain characteristics which regular pure-bred animals have. For example, polar bears have the ability to swim long distances in search of seals which polar-grizzly bears do not. If this hybridization continues, then the polar bear or the grizzly bear may be gone forever and only the hybrids will remain. Also, in addition to these bear hybrids, there have been reports of a narwhal-beluga whale hybrid along with one that is part bowhead whale and part right whale. Both of these animals, too, may lack certain characteristics which are usually associated with either one of the pure-bred whales. All of these animals need to be protected in such a way that would not result into any hybridization. And with climate change as the main culprit, one way to prevent this problem would be to reverse the greenhouse gas emissions within the next ten years.

View article here    

No comments:

Post a Comment