Describe how grizzly and polar bear evolution may be affected by climate change.

Climactic changes might currently be threatening the survival of polar bears (Ursus maritimus), but similar shifts appear to have played an important part in bringing the species into existence in the not too distant past.  

Researchers announced today that they have sequenced the mitochondrial genome of an ancient polar bear. The genetic traces they found in the bear's 110,000- to 130,000-year-old jawbone reveal that the species likely split from brown bears (U. arctos) just 150,000 years ago, at a time when specializing in arctic living quickly became an advantage rather than a liability.

The species' rapid evolution sheds new light on one of the emblematic species of climate change. Although the breed has become a popular flagship species for the issue, scientists knew little about how past climate affected the bear's evolutionary success.

The new genetic portrait gives a firmer frame to the polar bear's relatively rapid adaptations in the past. "From a conservation perspective it does tell us the polar bear has been through warming periods before," says Lisette Waits, a professor in the Department of Fish and Wildlife Resources at the University of Idaho, who was not involved with the research.

Explanation:

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explanation:

b,bacteria convert nitrates

into nitrogen gas.

d,plants and animals take in

and use nitrogen compounds.

e,bacteria break down waste    

products and return nitrogen  

to the soil.

a,bacteria convert atmospheric

nitrogen to ammonia.

c,bacteria convert ammonia

to nitrites and nitrates.