Global Warming Is Spurring Evolution, Study Says

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But as global warming makes Alaska more like Mississippi, the cues animals once relied upon will no longer match the climate.

(Read "Global Warming: How Hot? How Soon?")

Bradshaw and Holzapfel cite as an example the European blackcap, a bird that traditionally breeds in Germany and then migrates southwest for the winter to Spain and Portugal.

Some of these birds have begun to migrate west to England, which now has a suitable winter climate, the researchers say.

In the spring, these British birds can beat their Spanish cousins back to Germany, getting dibs on the best nesting sites.

Moreover, Bradshaw and Holzapfel note, the east-west migration pattern is instinctive, indicating that it's now embedded in the British birds' genes.

The upshot, Holzapfel says, is that some animals will be able to adapt to continued climate change, while others will have considerable difficulty.

"Large animals like polar bears will probably do very poorly," she said.

"They have a long life cycle, so it takes them relatively long to adapt genetically."

Over time, she said, "[ecological] communities will become completely different."

Animals and Natural Cues

Other ecologists agree.

The matching of organisms' life cycles to their environments is essential for survival, says Steven Running, forestry scientist at the University of Montana in Missoula.

Global warming, he says, is altering the optimal time for temperature-sensitive activities without changing the daylight cycle in any given place.

The result is a mismatch between the altered climate and the genetically programmed cues upon which organisms currently rely.

The ability of plants and animals to evolve in the face of these changes, Running said via email, "may well define what species are winners and losers in adapting to rapidly changing climates."

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