Snakes Evolve to counter poisonous toad in just 70 years

[Zac Naloen]

Snakes bite back at poison toads

Snakes in Australia have evolved to counter the threat of invasive, poisonous cane toads, scientists have found.

The toads (Bufo marinus) were only introduced in the 1930s but have already overwhelmed the local wildlife in Queensland with their rapid reproduction and toxic flesh, which kills many predators foolish enough to make them a meal.

But for two species of snake, at least, natural selection has produced a defence: the snakes have developed relatively smaller heads and longer bodies.

In essence, the reduced gape of the animals limits their ability to eat the toads likely to do them the most damage.

"We've got large lizards, such as monitor lizards, that seem to die after eating cane toads; a lot of our snakes after eating them will die," explained Dr Ben Phillips, of the University of Sydney.

"All the native frog-eating creatures in Australia, and the native cat that we have, are disappearing quite dramatically from areas where cane toads are turning up," he told the BBC World Service's Science In Action programme.

"Basically, large predators that would normally eat frogs are succumbing to cane toads quite dramatically."

Quick adaptation

The cane toad was introduced in 1935 to help control a crop pest, but has since become a nuisance itself.

Its range in Queensland has steadily expanded and the toad is now moving into New South Wales and the Northern Territory.

The way the two species of snake have adapted to cope with this challenge has been described as a classic example of "contemporary evolution".

The red-bellied black snake (Pseudechis porphyriacus) and the green tree snake (Dendrelaphis punctulatus) are highly susceptible to toad toxins.

And the presence of Bufo marinus has imposed an immense selection pressure on their populations.

"One of the ways the snakes seem to be fighting back is by changing their body shape. Basically, their heads have got smaller relative to their bodies (or their bodies have got bigger relative to their heads; whichever way you want to think about it)," said Dr Phillips.

"If a snake's got a small head, it's going to be able to eat a much smaller prey item."

"What that means is that because snakes eat their prey whole and the size of meal is entirely dependent on the size of its head; if a snake's got a small head, it's only going to be able to eat a small prey item.

"Thus, it's going to be able to poison itself a lot less effectively on a cane toad - which is probably a good thing, given that they seem to be a little bit silly about eating things that taste bad."

Natural selection ensures these are the snakes that prosper and reproduce; their head-body traits come to dominate populations.

Alien response

What seems remarkable is that this adaptation has occurred in just 70 years. But Dr Phillips says it should not be too surprising since snakes breed comparatively quickly.

"We need to remember that snakes have a generation time of two or three years; so basically that means a time of 20 to 25 generations has passed since the cane toads arrived in some areas," he said.

"That's a reasonable amount of time, evolutionarily speaking."

The University of Sydney researcher commented that it was encouraging to see that ecosystems could respond to problems imposed by invasive species.

"I think it's a bad idea to leave species around the place - it's almost impossible to know what kind of impact they will have," he said.

"But the upside of what we have found is that while it's all doom and gloom about the environment - we hear a lot of bad news - it's nice to see that Nature's looking after itself."

Dr Phillips and his colleague Dr Richard Shine published their work in a recent edition of the journal Proceedings of the National Academy of Sciences.

[Zac Naloen]

sorry, heres the link http://news.bbc.co.uk/1/hi/sci/tech/4073359.stm

[wautd]

Ive said it before and i say it again: toads are evil

cool news tough

[Lord Zentei]

sorry, heres the link http://news.bbc.co.uk/1/hi/sci/tech/4073359.stm

An excellent resource for creationist-bashing. Kudos

[Gustav32Vasa]

There is no such thing as evolution. God took pity on the snake and in His wisdom gave it immunity to the poison.

[Darth Wong]

Creationists won't accept it as evolution. One thing you'll quickly discover about creationists is that they use the Mother of All "No True Scotsman" fallacies in order to dismiss any and all examples of evolution. In short, they define evolution as some kind of crazy giant-leap mutation which creates a new species which looks totally different from the previous one, after passing through a transitional step which is a horribly mishapen unviable mish-mash of half parts from the old species and half parts from the new one. Since this never happens, and none of the examples of evolution we provide can fit this bizarre criteria, they can state confidently that evolution has never been observed.

And no, I'm not exaggerating. Not even a little bit.

[Zac Naloen]

There is no such thing as evolution. God took pity on the snake and in His wisdom gave it immunity to the poison.

Its not really immunity. They have smaller heads so they don't see it as prey anymore... they aren't smart enough to work out its bad for them too eat it, so natural selection made the decision for them.

[Lord Zentei]

Creationists won't accept it as evolution. One thing you'll quickly discover about creationists is that they use the Mother of All "No True Scotsman" fallacies in order to dismiss any and all examples of evolution. In short, they define evolution as some kind of crazy giant-leap mutation which creates a new species which looks totally different from the previous one, after passing through a transitional step which is a horribly mishapen unviable mish-mash of half parts from the old species and half parts from the new one. Since this never happens, and none of the examples of evolution we provide can fit this bizarre criteria, they can state confidently that evolution has never been observed.

And no, I'm not exaggerating. Not even a little bit.

Gosh. I haven't of course dealt with creationists as you have, but aren't they shooting themselves in the foot with such nonsense? Would they accept the real idea of evolution if it were sneaked under their radar under a different name since they obviously don't know what "evolution" means? Don't they accept the possibility of selective breeding then?

Or perhaps I'm being too logical about this...

[Kuja]

There is no such thing as evolution. God took pity on the snake and in His wisdom gave it immunity to the poison.

I think I just got a migraine.

*rubs head*

[Mayabird]

Or perhaps I'm being too logical about this...

You are. You're trying to think, instead of sticking your fingers in your ears, shutting your eyes, and saying "Lalalala can't hear you lalalala JESUS lalalala BIBLE lalalala..."

[Keevan_Colton]

Creationists won't accept it as evolution. One thing you'll quickly discover about creationists is that they use the Mother of All "No True Scotsman" fallacies in order to dismiss any and all examples of evolution. In short, they define evolution as some kind of crazy giant-leap mutation which creates a new species which looks totally different from the previous one, after passing through a transitional step which is a horribly mishapen unviable mish-mash of half parts from the old species and half parts from the new one. Since this never happens, and none of the examples of evolution we provide can fit this bizarre criteria, they can state confidently that evolution has never been observed.

And no, I'm not exaggerating. Not even a little bit.

I know. The dumbass with a phd that's meant to be teaching my class research skills (the irony) is a fundie moron. He's tried to claim flood geology is in scientific journals, and that the lack of "transitional" fossils shows evolution to be false.

[Durandal]

Oh come on. This is just micro-evolution. Where's the evidence for macro-evolution?

[Stravo]

I noticed one scientists note that 20-25 generations is a reasonable amount of time to evolve in response to pressure. SO does that mean that we can see some changes in humanity in 20-25 generations? Or are we currently lacking any sort of pressure on our population to change?

[Keevan_Colton]

I noticed one scientists note that 20-25 generations is a reasonable amount of time to evolve in response to pressure. SO does that mean that we can see some changes in humanity in 20-25 generations? Or are we currently lacking any sort of pressure on our population to change?

We've harnessed the nice big brains evolution was so kind as to give us and generally shoved our own natural selection off to one side. We adapt memetically more than we do genetically these days...the principle is sort of similar.

We're doing our best to keep evolution and its harsh side out of our way with technology.

[Lord Zentei]

I know. The dumbass with a phd that's meant to be teaching my class research skills (the irony) is a fundie moron. He's tried to claim flood geology is in scientific journals, and that the lack of "transitional" fossils shows evolution to be false.

Where the sam hill does a guy like that earn a phd? Perhaps you should ask him to put his money where his mouth is and provide a copy of said journal.

[Jalinth]

There is no such thing as evolution. God took pity on the snake and in His wisdom gave it immunity to the poison.

Its not really immunity. They have smaller heads so they don't see it as prey anymore... they aren't smart enough to work out its bad for them too eat it, so natural selection made the decision for them.

It sounds like very typical natural selection. A portion of the snakes were naturally small enough (or didn't have quite large enough bite sizes) to eat the toads. These survived, and the bigger brethern died (on a large scale). Very logical, reasonable explanation.

Now what I'm waiting for is for something to come along and be able to eat cane toads (that is somewhat immune to the poison). But that could take a very long time unless a native species already exists that has some poison immunity.

[Marksist]

Although, this is very cool news, the creationists have been ignoring the mountains of evidence for evolution for a long time now, and I don't know why they would stop.

[Darth Wong]

I noticed one scientists note that 20-25 generations is a reasonable amount of time to evolve in response to pressure. SO does that mean that we can see some changes in humanity in 20-25 generations? Or are we currently lacking any sort of pressure on our population to change?

Significant evolutionary changes have occurred in only a few generations. I recall one experiment with maize that caused effective speciation in only a few generations by artificially selecting specimens from two varieties which failed to cross-breed and destroying those that did. After something like four generations, they had almost complete speciation (something like 98% reliability of the two populations inbreeding rather than crossbreeding even when mixed). Obviously, with plants, there are no conscious behavioural factors at work; something else changed.

[Zac Naloen]

It sounds like very typical natural selection. A portion of the snakes were naturally small enough (or didn't have quite large enough bite sizes) to eat the toads. These survived, and the bigger brethern died (on a large scale). Very logical, reasonable explanation.

Now what I'm waiting for is for something to come along and be able to eat cane toads (that is somewhat immune to the poison). But that could take a very long time unless a native species already exists that has some poison immunity.

But thats exactly what natural selection is, the ones with the advantage survive to pass on their genes to the next generation, as the others die out the number of snakes with the advantage increases eventually replacing the original population.

[DPDarkPrimus]

Truely, God favors these snakes over the toads, just as he favors the faithful over the unbelievers! Repent, repent, or you shall be devoured by Satan, who shall ignore the poisons of of your sin... he shall, in fact, find them to be pleasing to his taste, much like an au jus!

[Symmetry]

I noticed one scientists note that 20-25 generations is a reasonable amount of time to evolve in response to pressure. SO does that mean that we can see some changes in humanity in 20-25 generations? Or are we currently lacking any sort of pressure on our population to change?

I'd imagine we're still evolving our natural beharior to cope with modern civilization (crowding, unaccaptability of casual violence, &c).

[Guy N. Cognito]

I noticed one scientists note that 20-25 generations is a reasonable amount of time to evolve in response to pressure. SO does that mean that we can see some changes in humanity in 20-25 generations? Or are we currently lacking any sort of pressure on our population to change?

I'd imagine we're still evolving our natural beharior to cope with modern civilization (crowding, unaccaptability of casual violence, &c).

Uh.... I'm not sure what you are saying is quite true. We are more then likely weakening the gene pool since the pressures on our race are less and less every year. Every time something comes along and it's fatal to portions of our civilization, we use our brains and overcome it, that's note really evolution, but learning. And I don't think there is anyhting stopping people from moving out of highly crowded metropolitan area, so there's no real natural selection there. I think while we are learning, we aren't really evolving.

[CJvR]

We're doing our best to keep evolution and its harsh side out of our way with technology.

No, we are not. The evolutionary process is still going on. Think about the declining birthrates in the western world, and indeed in all industrialised societies. It matters not how fine and advanced a civilisation we build, it matters not how smart and beautiful we are. If we have no children to carry on excess brains will be an evolutionary dead end and then it will be up to the chimps to carry the primate baton, provided we don't exterminate them first...

[Justforfun000]

Hmm, I wonder if in time the human race can evolve to be immune to alcohol. We're certainly using it enough.

[Darth Wong]

Hmm, I wonder if in time the human race can evolve to be immune to alcohol. We're certainly using it enough.

Hypothetically, if one were to execute all alcoholics, eventually the predisposition toward alcoholism would be largely removed via artificial selection.