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Omaha Steve

(99,608 posts) Thu Oct 16, 2014, 10:40 AM Oct 2014

Watch Out, Kangaroos: Poisonous Cane Toads Are Evolving Into Even Deadlier Invaders

http://www.takepart.com/article/2014/10/14/watch-out-kangaroos-cane-toads-are-march-and-theyre-evolving-even-deadlier?cmpid=tpdaily-eml-2014-10-15

The imported pest has devastated Australia's wildlife, and now the cane toad has developed the ability to spread farther and faster across the continent.

(Photo: Ian Waldie/Getty Images)

October 15, 2014 By John R. Platt

John R. Platt covers the environment, technology, philanthropy, and more for Scientific American, Conservation, Lion, and other publications.

Not everything about evolution is good. Case in point: Invasive cane toads in Australia have started evolving to jump straighter and farther than ever, allowing them to quickly expand into new regions and creating an even greater threat to Australia's native wildlife.

Cane toads were first imported to Australia from Hawaii nearly 80 years ago, when the first 100 amphibians were brought to northern Queensland to fight a native beetle devastating the sugarcane crop. That didn't work. There are now an estimated 200 million cane toads in Australia, and they have spread across thousands of miles. The massive invaders not only eat anything smaller than them but also secrete a highly toxic venom that is deadly to anything that tries to consume them, whether a kangaroo that inadvertently swallows one or a snake on the hunt for dinner.

The toxic toads have proved particularly devastating to native predators such as the northern quoll, a cat-size marsupial, and a monitor lizard called the goanna. By the 1980s, the cane toad had reached Kakadu National Park, a cradle of biodiversity in the Northern Territory. “It is evident that a major decline of the northern quoll has occurred in Kakadu National Park, and will continue to occur, and that northern quolls may disappear from Kakadu National Park altogether within the foreseeable future due to the invasion of the cane toad,” the Australian Department of the Environment stated in a 2005 report. One recent study found that populations of Argus monitor lizards declined by 90 percent after cane toads arrived in their habitat. Even large predators such as freshwater crocodiles are not immune.

At first the cane toads' spread was relatively slow, but some have picked up the pace in recent decades, and the Australian government predicts they might reach the west coast of the country. According to research published on Oct. 8 in the Proceedings of the Royal Society B, that's because the toads are rapidly evolving. Those on the furthest edges of the "invasion vanguard" now hop in a relatively straight line and travel nearly twice as fast as those in areas where the toads have lived for years.

FULL story at link.