A Toxic Cane Toad: Super-quick evolution has allowed the cane toad, above, to invade Australia at a rate of 30 miles per year today, compared with seven miles per year in the 1950s.
Posted on 02/15/2006 1:30:20 PM PST by PatrickHenry
Fat, toxic toads at the leading edge of an Australian invasion have evolved longer legs than those behind the front lines, report biologists.
The alarming discovery not only means the toads can spread more quickly over the continent, but it raises the possibility that under the right conditions, animal evolution can happen in just decades, not eons.
That, in turn, has major implications for animals adapting to global warming, as well as biological pest control projects, which generally take for granted that carefully studied animals introduced to fight off invasive species can not evolve into something troublesome.
The inexorable, seven-decade-long expansion of cane toads from their disastrous introduction to Queensland in 1935 has long been monitored by biologists.
One such biologist was recently driving along a toad-crowded road one night, along the invasion front about 40 miles east of Darwin, when he noticed how desperately the toads were hopping grimly toward him, all facing the same way: into virgin territory.
"It was just like an invasion in a science fiction movie," said biologist Richard Shine of the University of Sydney.
Shine is a snake specialist, but when the toads began heading toward his study area, he decided it would be wise to "know thine enemy" before they arrived, he explained.
So for years Shine and his colleagues have been tracking cane toads, and as a matter of course they weigh the toads and measure them. Those records came in handy when they discovered that some cane toads at the invasion front were covering an unprecedented mile-and-a-quarter (two kilometers) each night.
"Sure enough, there was a pattern," said Shine of their astonishing leg-length discovery.
Not only were the legs of pioneer toads significantly longer, but the same athletic build dies out among toads as areas become more settled.
In other words, there appears to be a great advantage to getting the first crack at virgin territory. That boils down to the opportunity to produce more viable tadpoles that grow up to continue the line. For seven decades now that advantage has been awarded to cane toads with the longest legs. That has lead to the steady breeding of longer and longer-legged toads that can keep beating the crowd.
The disheartening result is that the toad invasion rate has increased from seven miles per year in the 1950s to a whopping 30 miles per year today, report Shine and his colleagues in the Feb. 16 edition of Nature.
The silver lining is that the cane toads are showing how quickly some species can adapt to new environments, a challenge now facing innumerable species worldwide as the global climate warms, said ecologist and rapid evolution researcher David Skelly of Yale University.
"We never think of evolutionary changes happening that fast," said Skelly of his fellow ecologists.
That has to change, because the cane toads are just a high profile case of something that is being seen in many organisms all over the planet, he said.
"It doesn't mean that we have no problem (with climate change) or that all species will be viable," said Skelly. But there is evidence that many species might be more able to adapt than previously believed.
Another place where people have to start thinking about rapid evolution is at the federal and state agencies where they evaluate exotic species for release as biological checks on exotic pests, said Skelly.
Right now those agencies don't consider the possibility that a new exotic species will very likely change in its new environment, for better or worse. It's time they started thinking differently, he said.
Variability within a species may or may not eventually lead to speciation. If these long-legged toads get separated from their shorter-legged cohorts somehow, and other changes occor in their body such that the two populations can no longer interbreed, THEN you get a new species of toad.
Consider the example of a ring species:
http://en.wikipedia.org/wiki/Ring_species
You can get several populations with small differenes that will still interbreed. As small changes within one species build up, it happens that two groups that are capable of reproducing with some of the other groups in their "species" but NOT WITH EACH OTHER. At this point our whole definition of "species" kind of breaks down.
I found this particular comment in the article rather interesting: And a cooling of the lower atmosphere due to greenhouse gas emissions could delay the closing of the ozone hole, perhaps by a decade or so. So greenhouse gases cause cooling...but they're greenhouse so it should be warming...*sigh* we just can't win.
If the ozone layer is being depleted and ozone depletion causes increased rates of skin cancer, are we sufficiently adapting to it?
In terms of evolution, is our species adapting to it sufficiently, or are we, in time, going to become extinct like the dinosaur, and other species who have been evolving and adapting going to survive?
Just a little food for thought... since we get so caught up in our everyday lives that we often forget to look at the big picture.
And if the toads evolved into a higher order species, who is going to turn into a prince to live happily ever after with Snow White? Is that the right fairy tale? LOL! Have a good day. ;)
The thing is, there are so MNAY humans that any small advantageous mutations that would help us deal with increased UV radiation will be swamped out by the sheer size of our gene pool. Evolution tends to work fastest on small, genetically isolated populations. We really would have to mostly die out, or have some small subgroup be isolated on an island for a few hundred generations to see a truly distinct human species (home somethingorother as opposed to homo sapiens) emerge.
Species tend to be VERY stable over time, and only change if there is some kind of strong natural selective pressure. When such conditions arise, the change can be "rapid", although rapidity must still be measured in many thousands or millions of years. This is the heart of the idea of "puncuated equilibrium".
eye cint spil toody.
"For seven decades now that advantage has been awarded to cane toads with the longest legs. That has lead to the steady breeding of longer and longer-legged toads that can keep beating the crowd."
My favorite science words are: elegant, robust, significant, and 'needs more study.'
Unless they just like studying these toads in situ why don't they just hire a few Johnny Toad-seeders to scatter them from the front line to the shore and see how they adapt to that?
There's a lot of poo-flinging in these CrEvo threads.
And yes GreenFreeper, genetic variability is indeed incredible. I <3 God's design. :D
What's frustrating is how the common-sense understanding of selecting out for type becomes lost in the miasma of evolution/speciation.
Scientists develop new goat which gives almost twice the butterfat in its milk than other goats! (Well, no, that's the Nubian goat, and it developed through the efforts of livestock breeding/mgt, it also has long pendulous ears which are convenient air-conditioners in sultry places.) New goat is earless in the arctic! (there is a breed of earless goat, quite handy and hardy in nippy climates.)
When you partake in one sort of argument with an evo, he wants to claim that there's no connotation of speciation in the term, "evolution." Then he wants to claim that selecting out for type is evidence of "evolution." Then they try to bully you into signing on to their capricious, obsessive lists of definitions.
They need help. Asberger's Syndrome, Anonymous!!
Yes, and they can still keep a straight face and call it science.
Speciation events are closely tied to punctuation events. During these "speciation" events, a new species experiences a large magnitude of evolutionary change.
so they give us three central postulates:
1. Most evolution occurs in short, rapid bursts (punctuation events) followed by stasis. This produces a large morphological gap. (are'nt they so clever)
2. Most evolution occurs at speciation. (In other words, punctuation events are closely tied to speciation.)
3. Speciation has no inherent directionality. A daughter species tends to originate in a random, non-adaptive direction from the parent species.
Funny how these clever postulates made it difficult to explain adaptation. How can adaptation arise if change is concentrated in events that are random concerning adaptation?
So then they came up with species selection. According to this idea, entire species are selected, rather than individual organisms. Speciation is to species selection as mutation is to individual selection
Then if the Puncutationists are questioned they simply alter the concepts of species and selection.
And these Darwin addicts think we don't understand science?
Seriously, they should hang out with Howard Dean
Straight? um...
Maybe they already hang out with Howard Dean, or George Soros. Some vulnerable GOP pols are often mentioned derisively by evo-FReaks, Santorum in particular. Is it really so outlandish to wonder if liberal activists are about on the internet pretending to Care So Much About Science. (There will be a new documentary produced called "The Republican War on Science" made by the Supersize-Me guy who has associations with Soros.)
Do you know scientists who behave like these FRevos do? The practical scientists I know are uninterested in evolution, they're too busy doing their science. They sure wouldn't have the time to start and maintain dozens and dozens of threads every week on the same subject...which boils down to "look how dumb the conservative Christians are"--
It works like a push pol, and Soros has spent money on weirder things.
It's not just that it can walk faster, but it can cover more ground. As the article mentions the faster frogs are able to cover more ground per year than the frogs could decades ago. It stands to reason that the type of frogs furthest from ground zero will be of the faster variety simply because the slower types cannot get that far. Fast frogs produce more fast frogs. So it makes total sense that the front line should be dominated with fast frogs.
Yes Bob, it does make sense that the front line is dominated by long leg frogs, just as the olympic broad jump teams are dominated by long leg men, but neither has any relationship whatsoever to the dreams of evolutionists.
Their ability to get there first is simply a mechanical fact that has existred since they were created, but still isn't 'evolution.'
And which point would that be? The one where allele frequencies change due to RM/NS? Or the one where allele frequencies change due to intelligent agents? Or perhaps the one where allele frequencies change because of morality or immorality? I know it's not the points that Dawkins, Dennett and Lewontin make because reading or listening to them makes me itch. :-}
The situation with jump teams is totally different. The fast frogs did not used to exist, as evidenced by the increase in distance covered by the modern frontline variety. Ie the faster variety have appeared and totally dominated a specific range of the overall territory of this frog. That is due to simple natural selection. The frogs will be changing all the time. Some will be slower, some will be faster. The faster frogs happen to be able to spread further into areas not yet inhabited where they don't have any space competition.
That is a nonsensical statement. There is no way to have even compared present specimens with past specimens over the same terrain. To so state is grossly unscientific and falacious. We are talking about an invasive foreign species.
Belief in evolution has proven itself dishonest, and gullible again.
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