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[February 16, 2006]
Toxic cane toad develops longer legs to speed up its conquest of Australia
(The Daily Telegraph, Via Thomson Dialog NewsEdge)THE toxic cane toad is evolving longer legs to speed its takeover of Australia, scientists report today.
The introduction of Bufo marinus from the Americas more than 70 years ago was aimed at combating insect pests on sugar cane crops, as Australia has no native toad species.
But the toads proved unable to jump up and eat the cane beetles and looked elsewhere for food, starting an ecological disaster.
They now range over more than 400 square miles of the continent. They consume many native insects and because of their toxicity can kill lizards and snakes that eat or try to eat them.
A report in the journal Nature says that toads at the forefront of the invasion have developed longer legs than those in older and more established populations, enabling them to hop ever faster into new territory. Prof Richard Shine, of Sydney University, and colleagues stationed themselves at the invasion front 37 miles east of Darwin and waited for the toads, which can travel just over a mile a night. The first to arrive had longer legs, showing that evolution is favouring those leading the charge into new territory. "The toads in the vanguard had hind legs about 45 per cent of their body length,'' Prof Shine said. "Later arrivals had progressively shorter legs. When we looked at museum specimens gathered over a 60-year period from long-colonised areas, the relative leg length just kept dropping.'' Prof Shine told The Daily Telegraph: "I find it absolutely staggering that a small dumpy creature like a cane toad can travel over a mile a night - night after night.
"It is difficult to imagine that they will be able to go much faster unless they evolve jet propulsion.''
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