Evolved toads invading Australia at high speed

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Evolved toads invading Aust at high speed

 

By Sabra Lane

 

Scientists say cane toads are evolving so quickly, they will soon be on Sydney's doorstep and breeding in Perth, Adelaide and western Victoria.

 

A team of researchers from Sydney University has found cane toads are spreading across the continent at a much faster rate than previously thought.

 

The team, headed by evolutionary biologist Rick Shine, says the feral invaders have rapidly adapted to Australia's climate, after they were first introduced in 1935 to wipe out cane beetles.

 

Professor Shine says scientific modelling has come up with some grim predictions of just how far the pests will spread.

 

"The toads are remarkable invasion machines," Professor Shine said.

 

"In the course of about 50 generations in Australia, they've changed from quiet little meandering animals that don't travel very far to these road warriors on the invasion front that move every night, move long distances, move in straight lines.

 

"The invasion front's moving about six times faster than in the early days of toad invasion. They're incredibly impressive little animals."

High-speed evolution

 

Professor Shine says the feral invaders have adapted to the Australian environment so much quicker than previously thought that areas once thought impossible for the pests to survive in are now on the toad takeover map.

 

"They're going to extend much further than we really have anticipated," he said.

 

"Basically, people have expected that toads would only be able to live in the bits of Australia that have climates similar to the places they came from in South America.

 

"But our work is showing that the toads are evolving - they're adapting to Australian conditions.

 

"That means that the proportion of the Australian continent that they'll be able to invade is actually getting larger decade by decade.

 

"It now includes large areas of southern Australia... certainly a very large area of south-western Australia, around Perth and that whole corner of the continent, a big southern swathe down through Adelaide and western Victoria, and then some patchier spots along the New South Wales coast heading down towards Sydney."

 

He says cane toads have moved to areas with conditions like those of Sydney.

 

"The stage is set and it's a question of how the toads are going to get there," he said.