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Aga in Australia: Why do toads eat cannibalism – knowledge

People in Australia have tried everything to get rid of the cane toddler: hitting poisonous waterfalls with golf clubs, trying to infertility with the virus, and sending toad-eating meat ants by the neck. Nothing helped. Annually, anuras, up to 22 centimeters long and weighing more than a kilogram, advances about 40 kilometers southwest of the country. And the number is increasing: cane toads are squatting in the front doors of swimming pools and Australians, where they eat cat and dog food.

It seems like all of this is too much for the animals. Anyway, they started eating each other. More specifically, cane toad dotlings eat cane eggs and small cane burpots. An entire clutch is often destroyed in this way, while the eggs of other waterfowl species are usually saved. Why this is has been a mystery to biologists for a long time. Australian aga researchers have now discovered how dotpoles recognize the eggs of their own species, much like many waterfowl species. According to your studyIt is in the journal Science Ecology and evolution Apparently, tadpoles become neurotic when in contact with a poisonous cocktail, which is present in aga eggs, but not in the grip of other anuras.

In the first experiment, a team led by Michael Crossland of the University of Sydney isolated cane stalks from fish stocks. Ten Aga eggs swam in one of them, and ten eggs of various Australian frog species swam in each. After three to four days, how many eggs or animals left in the cane tadpole hatched from them. Very few of the survivors were descendants of Aga. Sugarcane tadpoles also lay eggs of other waterfowl species – but not statistically significant, the researchers said. Ecology and evolution To write.

Only in Australia do cane toads eat each other

In the second experiment, the scientists again placed the cane dotballs in the fishbowl with the eggs of their own species, but this time mixed the water with befo toxins, a toxic compound that protects the female cane toads from their predators. However, the poisonous cocktail had the opposite effect on the cane tadpoles: it aroused the appetite of the animals, with nothing in the clutch. If the researchers provided cane datpoles eggs, from which the young chicks would hatch, the animals would have completely cannibalized their relatives even without additional buffer toxins. So the researchers believe that when the eggs hatch, the toxin stored in the eggs is released and the datpoles become cannibalized.

Surprisingly, only cane toads in Australia have developed an appetite for individuals of their own species. Animals from Central and South America, the original location of these waterfalls, are not cannibals – although they are the same species. Until 1935 there were no cane toads in Australia. 110 samples were then imported to the continent from Venezuela. In Queensland, at that time they had to eat the larvae of beetles that destroyed crops in sugarcane plantations. The experiment went very wrong: the only thing toads don’t like are insects.

Otherwise, to this day they swallow everything that fits in their mouths, mostly whole: insects, spiders, worms and snails, but also other waterfalls, small mammals and birds. A special feature of the cane toad is its ability to lurk in front of hives, intercepting honey and pollen-bearing worker bees. There are now over 200 million cane toads in Australia – with dramatic effects on many native species. Other frogs, for example, have about two hundred different species in Australia. The cane toad has completely displaced some of them. Sugarcane toads are estimated to be more numerous in Australia today than any other frog species.

Waterfalls have become their enemy

But large animals are also threatened by cane toads because they poison themselves and die if the toad wants to eat them. Some monitor lizard species, for example, have disappeared from certain areas after the cane toad migrated there. And snake species that were once common have become rare in many places. Cane toads are also poisonous to humans. Even mere contact with the skin can cause severe irritation.

According to researchers, the fact that animals became cannibalistic in Australia may be due to the fact that they breed there much faster than their original homeland. “The density of sugarcane toads in Australia is much higher than their origin,” says Michael Crossland. “And at extreme densities, the evolution of cannibalism is possible.”

Scientists have estimated that there are 1,000 to 2,000 toads per 100 meters of beach in Queensland. In this situation, other animal species also become cannibalistic. Rats and hamsters, for example, feed on their offspring when they are at risk of overgrowth and food shortages. So Australia’s cane toads have become victims of their own success and are now their own worst enemies. Waterfalls take what their peers do best: Eat.

What attracts the authors of the present study is the speed at which the waterfalls became neurotic. They believe that buffalo toxins released by the eggs of their own species, especially during hatching, are inherited by Australian animals. If true, the cannibalism of sugarcane toads on the continent may be the result of an evolutionary process. However, something very quick, because the toads came to Australia 87 years ago. Compared to other evolutions that have taken thousands or millions of years, this is less than the blink of an eye.