• A cane toad, probably waiting to breed (pixabay)Source: pixabay
Messing with the genetics of an invasive cane toad population could stop their spread through "genetic backburning".
Kemal Atlay

24 Feb 2016 - 4:32 PM  UPDATED 25 Feb 2016 - 11:30 AM

Scientists have suggested a new and potentially powerful tool for stopping the spread of invasive species such as the infamous cane toads (Rhinella marina).

The idea, called ‘genetic backburning’, involves taking a subset of the invasive species that is fitter but less effective at dispersing, and transporting them to the invasion front to out-compete the main population for food and habitat.

According to the researchers, genetic backburning could make it easier to stop the spread of invasive species, and they describe this strategy in a paper published today in Proceedings of the Royal Society B.

“In the right circumstances, it can potentially be a powerful tool for halting invasions at natural chokepoints and natural landscape barriers,” says lead author of the study Dr Ben Phillips, an expert in ecology and dispersal evolution from the University of Melbourne.

“One of the ways that we could make invasion fronts easier to stop is actually to take some of those individuals from back in the [main population], the low dispersing individuals, and put them in front of the invasion front.”

Learning from bushfires

The idea, which is purely theoretical at this point, builds on the concept of backburns ahead of the bushfire season, where fire crews will burn dry bushland in an attempt to stop the spread of future potential bushfires.

Dr Phillips used the spread of cane toads in northern Australia as an example of how rapidly invasive species can spread across great distances.

“The invasion front is made up of individuals that can potentially move huge distances relative to the individuals back in the core of the [main population],” Dr Phillips said.

Cane toads were first introduced to Australia in 1935 to control pest beetles that were destroying sugarcane crops in Queensland; over the decades, they have spread both south to New South Wales and west into the Top End.

Not only do cane toads compete with native wildlife for food and shelter, they are also highly poisonous, often killing any predator that takes a bite – this problem has been directly linked to the decline of northern quolls and large goannas in Kakadu National Park.

According to Dr Phillips, in the next decade cane toads could move through The Kimberleys until they encounter the landscape where the Great Sandy Desert meets the northern coast of Western Australia.

Could work in theory

Associate Professor John White, an ecology expert from Deakin University, told SBS  Science that the idea of genetic backburning has merit, but he questions its effectiveness in actually eradicating invasive species.

“It doesn’t necessarily deal with the fact that the species are still in the system,” says White. “What it’s doing is trying to effectively constrain the area over which [the species] spreads.”

“Theoretically, you could create a barrier of individuals that never disperse and swamp the gene pool with that.”

However, he thinks that it could be used as part of a two-step approach where scientists could first slow the spread of the species before actually dealing with eradication.

“Half the problem with trying to manage these things is the fact that they spread rapidly,” says White. Therefore even slowing their spread could turn the invasion into a manageable problem.

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