Friday, November 23, 2012

Climate change creates the “pizzly bears” – A threat to the biodiversity

The polar bear and the grizzly bear are both endangered species. The world's 20,000 to 25,000 remaining polar bears are classified as vulnerable, with decreasing Arctic sea ice reducing their chances of hunting and breeding. Increasing greenhouse gas emissions are largely responsible for the deterioration of the polar bear's habitat, and the genetic diversity of the population has also suffered as numbers have decreased. The Grizzly bear populations has decreased from 100 000 to less than 1000 between 1800 and 1975. This decline is due to livestock depredation control, habitat deterioration, commercial trapping, unregulated hunting and the perception that grizzly bears threats human life.

Both of the two bears have important ecological roles. The polar bears are the top predator within its range. And the Grizzly bears have several ecological roles such as regulating prey populations, by foraging for tree roots or plant bulbs they stir up the soil, and thus increases species richness and causes nitrogen to be dug up from lower soil layers that makes the nitrogen more readily available in the environment.

Hybrids are often inferior to their parents because they are not as well adapted to their environments. The melting Arctic ice and warmer temperatures has brought polar bears and grizzly bears together by forcing polar bears on land and grizzly bears further north. Their hybrid offspring known as pizzlies have been detected on Canadian islands. The pizzly bear have patches of brown in their white fur, move like polar bears when they catch seals, they have shortened necks that make them less good swimmers and have long claws that are poorly suited to ice. This hybrid offspring is threatening the survival of rare polar animals, because in the, end it is conceivable that only the hybrid will survive. Even though the offspring is fertile it will not have the same ecological role as its parents. This is a threat to biodiversity. The same is currently happening to coyotes and wolves in North America as well.

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Posted by Åshild Saastad

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