Rapid Evolution in Cane Toads


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Cane toads were introduced to Australian cane fields of Queensland in the 1930s to control insect pests. Unfortunately, the toads did not control the beetles that they were brought in to control. Instead, the toads began spreading through Queensland, and on to the Northern Territories and New South Wales. The toads are voracious and grow very large when food is plentiful, frequently up to 2kg (~4.4 lbs). They have contributed to the decline of native amphibians by preying on native species, and they have few natural predators themselves because they are toxic. The toads were spreading across Australia at about 10km/year but now are spreading at an increased rate of 50km/year. Scientists studying the toads have demonstrated that the toads' legs have increased in length since they were introduced, allowing them to cover more ground faster. This is a remarkable rate of evolution, especially since evolutionary change in vertebrates is generally considered to occur much more slowly. The implications of this study for invasive species management, as well as other ecology fields, are serious as it is clear that non-native species are capable of quickly adapting physically to exploit new environments.

Nature article

Overview and history of problem with pictures of toads.

Radio story