December 21, 2010

It Never Ends!

FROM-Tehran Times

Melting Arctic ice heralds new polar hybrids: Pizzlies and more

An odd-looking white bear with patches of brown fur was shot by hunters in 2006 and found to be a cross between a polar bear and a grizzly bear.

Apparently, grizzlies were moving north into polar bear territory. Since then, several hybrid animals have appeared in and around the Arctic, including narwhal-beluga whales and mixed porpoises.

The culprit may be melting Arctic sea ice, which is causing barriers that once separated marine mammals to disappear, while the warming planet is making habitats once too cold for some animals just right.

The resulting hybrid creatures are threatening the survival of rare polar animals, according to a comment published Wednesday (Dec. 15) in the journal Nature.

A team led by ecologist Brendan Kelly of the National Marine Mammal Laboratory counted 34 possible hybridizations between distinct populations or species of Arctic marine mammals, many of which are endangered or threatened.

The “The greatest concern is species that are already imperiled,” said Kelly, first author of the Nature comment. “Interbreeding might be the final straw.”

When hunters encountered a hybrid of a polar bear and a grizzly in 2006, Kelly's colleagues remarked that the incident was just a fluke. But as Kelly delved into the issue, he found more evidence of similar anomalies.

In 2009, a cross between a bowhead and a right whale was spotted in the Bering Sea, between Alaska and Russia. And a museum specimen in Alaska attests to breeding between spotted seals (Phoca largha) and ribbon seals (Histriophoca fasciata), which belong to different genera, a scientific classification of organisms that is broader than the species level.

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