In other news
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, 12:06 PM
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09-03-2021
, 04:53 PM
09-03-2021
, 07:42 PM
Invasive cannibalistic toads are evolving so fast they’re pushing the limits of evolution
For cane toads in Australia, the biggest enemy is often… other cane toads. Cannibalistic tadpoles often munch on hatchlings like it’s an eating contest, and they do it so much they’re pushing the hatchlings into developing quicker — but this comes at a cost.
The first cane toads (about 100 or so) were brought to Australia in 1935, in an attempt to control the cane beetles that had been running rampant through the plantations. Not only did the toads not eliminate the beetles, but they became a problematic invasive species themselves, multiplying way beyond control.
It’s a sad story that Australia went through multiple times, with different animals. Because they are poisonous, the cane toads (Rhinella marina) have no natural predators, and went on to grow and spread throughout large swaths of the country.
But although adult toads can be quite menacing (measuring 25 cm, or 10 inches long), it’s their tadpoles that are carnivorous (at least most of the time).
It’s not that uncommon for tadpoles to become cannibalistic, many frog and toad species do it. Normally, they only get snippy and try to eat their relatives in the pond when resources are scarce. But in the case of the Australian cane toads, this seems to be happening a lot.
A single clutch can have thousands or even tens of thousands of eggs. The tadpoles that hatch earlier can then gobble up the unhatched eggs — and they do it like there’s no tomorrow. Researchers have documented cases where over 99% of the hatchlings in a clutch were consumed by just a few tadpoles...
Hatchlings in Australia are developing at a much faster pace than the others. This comes at a cost — when they reach the tadpole and mature stages of their life, they will not be as well-developed as their non-Australian peers, but it beats being devoured by a tadpole.
Even more impressively, the hatchlings seem to speed up the pace of their development when they sense a chemical released by other tadpoles. Since it’s not worth developing quicker when there’s no risk of cannibalism, the hatchlings only do it when they sense a risk.
Although cannibalism is generally a dangerous strategy, in the case of the cane toads, it could actually be helpful. Tadpoles that consume their relatives aren’t just getting a lot of nutrients — they’re eliminating competition for the pond resources, which are sometimes scarce. They develop to mature toad stage faster and tend to be larger.
But the good news is that at the very least, this works as a form of population control, limiting the spread of the invasive species.
It’s also a remarkable demonstration of how fast evolution can trigger changes. The toads roaming Australia now are notably different from those who first stepped foot on the continent. Australian cane toads are a frightening bunch: not only are they cannibalistic invaders, but they’re also evolving at a very rapid pace.
For cane toads in Australia, the biggest enemy is often… other cane toads. Cannibalistic tadpoles often munch on hatchlings like it’s an eating contest, and they do it so much they’re pushing the hatchlings into developing quicker — but this comes at a cost.
The first cane toads (about 100 or so) were brought to Australia in 1935, in an attempt to control the cane beetles that had been running rampant through the plantations. Not only did the toads not eliminate the beetles, but they became a problematic invasive species themselves, multiplying way beyond control.
It’s a sad story that Australia went through multiple times, with different animals. Because they are poisonous, the cane toads (Rhinella marina) have no natural predators, and went on to grow and spread throughout large swaths of the country.
But although adult toads can be quite menacing (measuring 25 cm, or 10 inches long), it’s their tadpoles that are carnivorous (at least most of the time).
It’s not that uncommon for tadpoles to become cannibalistic, many frog and toad species do it. Normally, they only get snippy and try to eat their relatives in the pond when resources are scarce. But in the case of the Australian cane toads, this seems to be happening a lot.
A single clutch can have thousands or even tens of thousands of eggs. The tadpoles that hatch earlier can then gobble up the unhatched eggs — and they do it like there’s no tomorrow. Researchers have documented cases where over 99% of the hatchlings in a clutch were consumed by just a few tadpoles...
Hatchlings in Australia are developing at a much faster pace than the others. This comes at a cost — when they reach the tadpole and mature stages of their life, they will not be as well-developed as their non-Australian peers, but it beats being devoured by a tadpole.
Even more impressively, the hatchlings seem to speed up the pace of their development when they sense a chemical released by other tadpoles. Since it’s not worth developing quicker when there’s no risk of cannibalism, the hatchlings only do it when they sense a risk.
Although cannibalism is generally a dangerous strategy, in the case of the cane toads, it could actually be helpful. Tadpoles that consume their relatives aren’t just getting a lot of nutrients — they’re eliminating competition for the pond resources, which are sometimes scarce. They develop to mature toad stage faster and tend to be larger.
But the good news is that at the very least, this works as a form of population control, limiting the spread of the invasive species.
It’s also a remarkable demonstration of how fast evolution can trigger changes. The toads roaming Australia now are notably different from those who first stepped foot on the continent. Australian cane toads are a frightening bunch: not only are they cannibalistic invaders, but they’re also evolving at a very rapid pace.
09-05-2021
, 12:11 PM
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, 10:20 PM
09-09-2021
, 05:58 AM
