A Moment of Science

Invasion Can Be Hard on Invaders

While we all know that invasive species are particularly hard on native species in the environment, invasive species can have it pretty tough too.

Motionless cane toad

Photo: Edwin Nollen (flickr)

Cane toads like this one were introduced in Australia in order save sugar cane crops, but the plan backfired

While we all know that invasive species are particularly hard on native species in the environment, but to play devils advocate, invasive species can have it pretty tough too.

Many studies have investigated the negative impact that invasive species have on natural ecosystems, but a study of invasive cane toads in Australia focused on challenges faced by invaders.

Cane toads are large poisonous toads from South America. They were introduced into Australia in the 1930′s with the hope that they would eat the cane beetles that were destroying sugar cane crops.

Unfortunately the toads didn’t eat the beetles, but did eat almost every other small animal or insect in their path. The voracious toads are a double threat to the Australian ecosystem, because the toads are so poisonous that many Australian predators, including pets, have died from eating them.

The cane toads’ success is due, in part, to how fast they migrate. A toad may move a half mile each night looking for new food and breeding opportunities. Since the fastest toads are the most successful, natural selection has resulted in larger toads with longer legs with each generation. However, speed has costs too. The researchers discovered that some of the largest toads develop severe spinal arthritis, and are more susceptible to infections than smaller, slower individuals.

Scientists hope that by understanding the impacts that invasion has on the invading species, they might discover new ways to stop invaders in their tracks.

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