http://www.cnn.com/TECH/science/9811/25/sudden.evolution.ap/
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In the fruit fly experiments, the Chicago researchers determined that the genetic variations held in reserve depended on a protein called Heat shock protein 90.
Hsp90 is known as a chaperone protein. As temperatures rise, it prevents other proteins from going awry and disrupting normal cell functions and growth, and also prevents degenerative diseases.
However, Hsp90 gets spread too thin when conditions continue to deteriorate. With the chaperone distracted, many different proteins begin to misfire in cells. Genetic variations that were held in reserve begin to trigger.
In the experiments, the researchers deliberately reduced the levels of Hsp90 in fruit flies to simulate the biological response in fruit flies to climate change.
As many as 90 percent of the flies' offspring emerged with oddly shaped wings, strange bristle configurations and limb deformities. The eventual evolutionary benefits of these genetic changes were unknown, the researchers said.
The abnormalities persisted even when Hsp90 levels were returned to normal in later generations, suggesting the changes had become permanent in the fruit flies' genetic code, Lindquist said.