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Flying Ability Lost, Re-evolved Four Times In Walking Stick Insects


LONDON (Reuters) -- In a finding that suggests that even the theory of
evolution evolves, scientists have shown that some insects lost and then
regained their ability to fly.

Researchers had thought that it was impossible for an organism to
re-evolve a complex trait like wings but walking sticks, small insects
that look like twigs, have proven them wrong.

After examining DNA from 35 species of walking sticks, evolutionary
biologist Michael Whiting and his colleagues at Brigham Young University
in Utah found that wings had been lost in some of the primitive insects
and then re-evolved at least four times over tens of millions of years.

"Traditional thought for the last two centuries has been that wings had
only evolved once in evolution but our study demonstrates that in walking
stick insects wings were re-evolved on multiple occasions," Whiting said. 

 The research reported in the science journal Nature challenges basic
beliefs of evolution -- that wings evolved only once in insects and that
if a trait is lost it cannot be regained.

It also opens a new direction for research because it shows that once a
complex figure has evolved it can be maintained over a long evolutionary
period even if it isn't apparent on the outside.

Over a 50-million year period, even though the stick insects did not have
wings, the genes for creating them appeared to have been maintained. 
Whiting said the genetic instructions to produce wings and legs are
probably related and can probably be switched on and off over millions of
years. ...