angelrose
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http://www.news.com.au/common/story_page/0,4057,11838285%5E13762,00.html
Snakes leapfrog evolution
By Brian Williams
January 3, 2005
RESEARCHERS believe two species of snake have evolved their body shapes so they can eat cane toads without being killed by the amphibian's poison.
The red-bellied black and golden/green tree snake have developed smaller heads and larger bodies. Snakes with a small head can eat only small toads, therefore ingesting less poison. A larger body also allows better absorbtion of larger doses of poison.
University of Sydney evolutionary biologist Rick Shine said the heads of black snakes and tree snakes seemed to have decreased by about 10 per cent and, while maximum body sizes had not changed, minimum sizes had increased. It had taken about 20 generations for this to occur over a 70-year period.
Researchers compared four species held by the Queensland Museum since before toads were released in 1935, and noted consistent shifts in the black snake and the tree snake.
"It looks for all the world like an evolutionary response to a new challenge put upon the system," Professor Shine said.
Snakes leapfrog evolution
By Brian Williams
January 3, 2005
RESEARCHERS believe two species of snake have evolved their body shapes so they can eat cane toads without being killed by the amphibian's poison.
The red-bellied black and golden/green tree snake have developed smaller heads and larger bodies. Snakes with a small head can eat only small toads, therefore ingesting less poison. A larger body also allows better absorbtion of larger doses of poison.
University of Sydney evolutionary biologist Rick Shine said the heads of black snakes and tree snakes seemed to have decreased by about 10 per cent and, while maximum body sizes had not changed, minimum sizes had increased. It had taken about 20 generations for this to occur over a 70-year period.
Researchers compared four species held by the Queensland Museum since before toads were released in 1935, and noted consistent shifts in the black snake and the tree snake.
"It looks for all the world like an evolutionary response to a new challenge put upon the system," Professor Shine said.
