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Toad toxin resistance evolves four times, same pathway

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From New Scientist:

Sometimes evolution just doesn’t have a choice. Reptiles have evolved to resist toad poisons four separate times, and each time they have made precisely the same biochemical changes to do it.

What’s more, an even wider range of animals show similar adaptations in response to these toxins, giving us by far the most extensive illustration of so-called convergent evolution to date.

“so-called” convergent evolution? Yup. That’s what it is called. Gotta problem with that?

This striking convergence on a few evolutionary outcomes probably occurs because sodium channels play such a critical role in cells. “There are very few options for a gene to modify itself to develop resistance without impairing function,” says Casewell. “It suggests that in this system, evolution can be highly predictable.”

Too bad no one predicted it then. Funny, the way things like this are always foudn to be highly predictable after their discovery.

See also: Evolution appears to converge on goals—but in Darwinian terms, is that possible?

Convergent evolution is evidence that evolution can happen. But the Darwinian model does not seem to be the right one. The life forms appear to be converging on a common goal.

That said, the problem presented for Darwinism by convergent evolution has hardly penetrated the world of pop science writers, high school teachers, politicians, judges, theologians, and entertainers. Mere evidence could not compete with a position so compelling as Darwin’s. More.

gpuccio, this functionally complex post of yours convinces me it had an intelligent cause. ;) Mung
News: If I must be sincere, I don't think you have really a point here. I agree with you that, in general terms, the concept of "convergent evolution" is simply a ridiculous tool to "explain" what cannot be explained. For example, it is really difficult to envision the multiple indipendent "evolutions" of flight as a credible pattern (indeed, even once would be incredible, but many times?). But the point is: convergent evolution is impossible, provided that it is convergent evolution of a complex trait. For example, even a new single functional protein. Or more complex networks, as in the case of flight. But, in the case mentioned in the OP, it is cleraly a case of very simple "convergent microevolution". I quote "In all these animals, the gene coding for the sodium channel had changed, altering the same two amino acids in identical ways each time. As a result, the toxin can no longer block the channel." IOWs, it is a scenario not very different from the simplest forms of antibiotic resistance, where the variation of a single aminoacid, or a couple, can confer the resistance. As discussed even by Behe, such events are in the range of what RV + NS can do. Now, if we observed the "convergent evolution" of a functional sequence of, say, 100 AAs, that would be all another thing. I believe that we must always keep in focus the concept of "functional complexity", which is central to all ID thought. While the functional specification is the qualitative key, it's the complexity of that specification which gives us the quantitative power to make the design inference. gpuccio
Convergence on a common goal is a feasible explanation for evolution if one assumes an underlying pattern. Darwinism explicitly denies such goals, or at least its current pundits tell us so. News
YES they keep on bumping into this. Like results for like needs. It seems defying the roll of the dice that evolution preaches built complexity. Imagine the creatures now extinct that EVOLVED response to toads etc. Why does it not hint/suggest there are other mechanisms other then selection/mutation that force creatures to like results. Why is complexity claimed by evolution but then said there are not many options. OPTIONS!! Complexity is about options. Evolution is about options. No excuses. Its a rising problem for serious thinkers to explain such common like answers for like needs in unrelated creatures. There must be a probability equation here that evolutionism is defying. I think convergence evolutionism claims is the soft underbelly in the error of evolutionism. Watch those toads!! Robert Byers
This is exactly what we would expect if Evolution is true. Andre

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