Australasian Science: Australia's authority on science since 1938

It’s Evolution – But Not As We Know It

Cane toad

Perhaps some other process, not natural selection, is responsible for the evolved acceleration of the toad invasion.

By Rick Shine

The accelerating pace of the cane toad’s advance through tropical Australia has revealed a new mechanism of evolution.

Rick Shine is a Professor in Biology at the University of Sydney.

The full text of this article can be purchased from Informit.

Big ideas can appear when you least expect them, especially when you are busy working on some straightforward research project. That’s exactly what happened to me and my colleagues, Greg Brown and Ben Phillips, in the course of our ecological studies on the invasion of cane toads.

We discovered that the toad front has accelerated as it has travelled through Australia, and in trying to understand why we realised that the answer may lie in a new evolutionary process. The process – which we have dubbed “spatial sorting” – occurs in parallel with the mechanism of natural selection proposed by Charles Darwin, but it’s very different from anything that Darwin suggested.

The story began 75 years ago, when some agricultural scientists foolishly introduced giant South American cane toads to tropical coastal Queensland. The toads didn’t have much effect on the cane-eating beetles they were meant to control, but found Australia to their liking. They soon spread southwards along the coast into north-eastern New South Wales, and westwards across the Gulf of Carpentaria and through the Northern Territory. Last year they crossed the Western Australian border, and the toads are currently moving into the Kimberley.

The result has been devastating for some of the native animals that try to eat the toads, presumably mistaking them for native frogs. Australia doesn’t...

The full text of this article can be purchased from Informit.