[ad_1]
In Australia, poison cane frogs have become their worst enemies.
For decades, scientists have witnessed cane tadpoles devouring their young relatives in shared puddles and ponds. The reason for his cannibalistic behavior was a mystery until now.
a new studyPublished this month in the journal Ecology and Evolution, found that Australian cane toad tadpoles develop an insatiable appetite when exposed to a toxin found in cane frog eggs, the same toxin that makes frogs poisonous.
Native to South America and Central America, cane toads were introduced to Australia in 1935 by scientists who hoped it would reduce the number of cane beetles that are causing problems for Australia’s sugarcane farmers. With prey in abundance and no predators able to withstand their venom, toads quickly numbered in the tens of millions and became an invasive pest squeezing native amphibians in Australia from their habitats.
But something changed when they settled in their home in Australia. Such cannibalism among cane toads has not been observed in the frog’s natural range. It has only been observed in Australia in recent years, indicating that this behavior is rapidly evolving in the Australian population.
“This is a unique situation where we can see evolution happening extremely fast and in real time,” said Jayna DeVore, a postdoctoral researcher at the University of Sydney and author of the study.
A little over a decade ago, scientists in Australia, including University of Sydney research fellow and study author Michael Crossland, were studying the effects of toads on native frogs. discovered Cane frog tadpoles had a voracious appetite to hatch cane frog eggs, even if other amphibian eggs were offered, flocking to traps that baited with them.
This is Dr. Crossland to conduct a series of experiments to better understand this phenomenon. Last year, he and his Macquarie University biologist colleague Richard Shine proved that cane toad tadpoles are interested in chemical compounds associated with toad eggs and hatchlings. These eggs are chemically similar to those of other amphibians, but with one key difference: They contain buphadienolite toxins, the same chemical that makes cane frogs poisonous and protects them from predators. The researchers suspected it was this chemical that triggered the tadpoles to feed on younger members of their species.
In their latest study, the researchers bred wild cane frogs, put the tadpoles in tanks with varying amounts of bufadienolite toxin in the water, and offered them cane frog eggs as well as Australian frog species. Tadpoles, which were not exposed to the bufadienolite toxin, barely gnawed frog and toad eggs. However, tadpoles exposed to bufadienolite toxin enjoyed consuming both native frog eggs and eggs of their own species.
The researchers also presented the tadpole eggs as they hatched. They found that the hatching process caused the tadpoles to exhibit the same cannibalistic hunger as when bufadienolite toxin was added to their water. This suggests that the toxins inside the eggs were released into the water when the fry hatched from them.
“We knew for a while that they were extremely cannibalistic, but this explains the mechanism that drives this cannibalism,” said Matthew Greenlees, a cane toad expert and postdoctoral researcher at Monash University who was not involved in the study. .
The study’s authors argue that Australian cane frogs likely evolved this response to their own toxins to reduce the number of other cane frogs in their habitat.
Dr. “It is well known that frog tadpoles in Australia compete very vigorously with each other,” Crossland said. “The density of cane frogs in Australia is much greater than their natural range, and under high-density conditions, cannibalism is likely to evolve. They are basically working on a way to eliminate future competitors.”
Dr. Crossland said it was “incredible” that cane frogs were able to evolve this cannibalistic behavior in such a short time. “Frogs arrived in Australia only in 1935. That’s the evolution of fast motion.”
Invasive species tend to evolve faster than native species, in part because they reproduce rapidly. This allows scientists to track evolution over decades as opposed to centuries or millennia.
Researchers believe that toads in Australia did not evolve. For their next research, they plan to examine how juvenile toads have evolved to defend themselves against their cannibalistic elders. Dr. “This is really an arms race between increasingly cannibalistic tadpoles and juveniles,” DeVore said.
[ad_2]
Source link