Invasive Cannibal Frog Species is Accelerating Evolution by Eating Its Own Offspring – Newsweek

Evolution is typically a slow processbut one toad species may have inadvertently figured out a way to speed it up: by eating their young.

Cane toads are native to Central America, but they were introduced to countries around the world in a failed effort to provide pest management on farms. The venomous species thrived in these new placesand in Australia, especiallyand are now considered one of the globe's most invasive species.

In Australia, the toads have no natural predators and will eat practically anything, including birds and small mammalsa combination of factors that has led to a rapid population boom, resulting in millions of cane toads across the region.

Because cane toads in Australia do not have any predators, the species' only threat lies in each other. If the population gets too big, cane toads will be forced to compete for increasingly scarce resources.

As a result, they began to eat their own hatchlings to keep their population numbers in check. This sort of cannibalistic behavior has been observed in the species' native populations, reported Smithsonian Magazine, but it is far more common in Australia, where the lack of predators makes overpopulation their primary concern.

However, a new study published in Proceedings of the National Academy of Sciences of the United States of America (PNAS) now suggests that young toad hatchlings are adjusting rapidly in an effort to avoid the cannibalistic behavior of their elders.

Within Australian cane toad populations, tadpoles will devour the hatchlings laid in ponds by female toads. "When these eggs first hatch, the young can't swim or eat yet, so they can pretty much only lie there on the bottom of the pond until they develop into tadpoles," explained the study's lead researcher, Jayna DeVore, to Live Science.

The cannibalistic behavior can only take place during this brief periodmerely a few daysbefore hatchlings have matured into tadpoles. "Once the hatchlings develop into tadpoles, they are too large and mobile for other tadpoles to eat them, so the cannibals have to work quickly if they want to consume them all," added DeVore.

As a result, cane toad hatchlings have started to develop at a faster rate than seen in their native populations, effectively minimizing the window where they may be eaten by tadpoles. Explained DeVore: "If cannibals are looking for you, the less time you can spend as an egg or hatchling, the better."

Developing faster may save hatchlings from an unfortunate, cannibalistic fate, but the accelerated maturation rate has its downfalls. Those that spent less time as hatchlings are less successful once they reach the tadpole stage.

While cannibalism seems like the sort of behavior that may lead to a population declineor even extinctionDeVore doesn't believe that's on the horizon for cane toads. "Australian cane toads may well be their own worst enemy, but I wouldn't expect them to go extinct anytime soon," she told Live Science.

"The good news is that cannibalism can control population growth," she added. "So, although cane toads are unlikely to drive themselves extinct, these cannibalistic behaviors may help to regulate their abundance post-invasion."

Newsweek has reached out to DeVore for further comment.

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Invasive Cannibal Frog Species is Accelerating Evolution by Eating Its Own Offspring - Newsweek