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Darwinian deadliness?

No, this isn’t about what you think. For once, we are talking about frogs and newts.

A friend notes that an evolutionary biologist puzzles as follows:

“One of the most puzzling paradoxes in the evolution of toxins is why organisms evolve to be deadly – contrary to venoms, for which deadly effects have a clear benefit. Extreme toxicity occurs repeatedly, from saturniid caterpillars to dart poison frogs. Selection favors the most-fit individuals, and those should be the ones that avoid predation. Killing an individual predator does not give an advantage over simply deterring one, especially if the prey has to be handled or eaten by a predator to deliver the poison. How, then, can we explain the evolution of deadly toxicity?” (Brodie, E. D., III. 2009. Toxins and venoms. Current Biology 19: R931-R935.)

Brodie, I’m told, is a leading researcher on evolutionary arms races at the University of Virginia. He goes on to suggest a solution: “arms races between predators and prey … drive the exaggerated evolution of toxicity in general, without resulting in deadly consequences to the primary selective agent.” (R933) He suggests as an example is the predator-prey relationship between garter snakes and a newt that produces tetrodotoxin powerful enough to kill 10-20 humans or thousands of mice. But the interesting thing is that the snakes, which seem to be the “primary selective agent” for newts, in the sense of selecting them for dinner, are resistant to the toxin. Brodie attributes the newts’ heightened toxicity to coevolution with the garter snakes.

My friend asks, “But how does that solve the paradox? Newts with a higher level of toxicity would only accrue selective advantage if those higher levels of toxicity protected them against the predators.”

Well, I suspect the answer lies in another question: What do we think the problem is, exactly? For a Darwinist, the goal is to persuade others that natural selection is the primary source of new information in the history of life. Therefore, the problem is “coming up with a Darwinian explanation”, however unsatisfactory it is. And my friend should know by now not to ask any questions if he really needs his job. (See Expelled.) Shut up, Brodie explained.

Of course, a non-Darwinist like myself would hazard a guess that no selection whatever is involved (because I don’t need selection to do anything in particular and am not looking for it when it probably isn’t there). If neither predator nor prey are affected by the prey’s toxicity to life forms that are irrelevant to their mutual ecology (such as humans), there is no reason the prey shouldn’t have as high a level of toxicity as is chemically consistent with its continued life. And for all we know, the toxin provides some hitherto unlooked for convenience for the newt.

Besides which, anyone who tried to research this topic up close and personal in the wild may now be referred to exclusively in the past tense … Jane Goodall lives on another street, I am afraid.

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9 Responses to Darwinian deadliness?

  1. I guess it is the population rather than the individual that is protected – If a predator eats a poisonous frog the predator dies and the rest of the poisonous frogs survive – and benefit because the predator dies.

    Predators that eat poisonous food die, which has a bad effect on their survival, so you then have selection in favor of predators that avoid poisonous food. (Many posionous creatures have vivid marking – no camoflage but a big signpost saying ‘Eat me and DIE’)

    It certainly is no benefit to the individual to be poisonous but it seems easy (from my POV) to see how a population of inedible creatures would be preserved by selection, even if a few of thm got eaten, and why selection would favour poisonous creatures that advertise their inedibility – because that DOES protect the individual.

    In other words if an inedible trait emerges in a population then it has an impact on the rate of predation for that population, which confers a survival advantage (for the population)

    The trait would only disapear, or fail to emerge, if the first member of the population to show that trait was killed before reproducing, of it all members with that trait got eaten (so the trait dies off)

  2. oops, that last sentence should be:
    or if all members with that trait got eaten (so the trait dies off)

  3. All these explanations seem to be mere speculations that are constructed to be consistent with the Darwinian paradigm. After all, there is no doubt that Darwin’s theory is true.

    Evolutionists are always insisting that scientific hypotheses must be testable. How does one go about testing this speculation — I mean hyptothesis?

    I am always amazed at how easily the phrases selection can produce this and selection can produce that flows off the lips of the evolutionist.

  4. You can test simple dynamics like this in simulation – in fact I’m pretty sure they probably have although I’m a bit to busy to dig through all the literature on population dynamics and co-evolution.

    The problem is that many ID supporters (but not me) tend to dismiss simulations as being designed to produce the results they produce.

  5. Yup, Googling for “population dynamics predator prey coevolution simulation” gives a lot of links like this:

    http://www.ncbi.nlm.nih.gov/pubmed/15315903

    (Linking didn’t work for this URL.)

  6. In other words if an inedible trait emerges in a population then it has an impact on the rate of predation for that population, which confers a survival advantage (for the population)

    The problematic part of this is that according to the evolutionary model, new traits only emerge in individuals, not in whole populations simultaneously. The traits must then spread through enough of the population to become established rather than wiped out through interbreeding. If the trait (like advertised toxicity) does not confer a selective advantage until established in a sizable population, why would it spread through that population to become established, as opposed to being wiped out?

  7. lars,

    Exactly, especially if it is 1. likely to be dangerous to the individual (poison!)
    2. must evolve concurrently with the spot or bright colors and device that protects it from its own poison.

  8. hmmm,

    this is somewhat relevant?

    “Please Be My Toothpick You Scrumptious Old Wrasse!”
    Excerpt: Goliath groupers that open their mouths to cleaning ‘minions’ such as the blue-streak cleaner wrasse defy deeply held expectations of nature’s ways as do sharks that extend their vicious jaws to pilot fish that then pick out food remnants from between their teeth.

    Extraordinary from a predatory perspective is the finding that wrasses and pilot fish are rarely (if ever) eaten by their much larger hosts. Discussions on the evolution of such partnerships leave the non-expert believing that chance mutations could simply turn predator ‘fearers’ into predator ‘lovers’ that naturally bond with their otherwise mortal enemies. Evolutionists weigh in by further supposing that reciprocal mutations led these same enemies to offer VIP treatments to their tasty servants.

    Hornyanszky and Tasi nevertheless spare little in their decrial of the evolutionists’ hand-waving ideals.
    http://www.uncommondescent.com.....ld-wrasse/

    Barracuda Teeth at Cleaner Wrasse Cleaning Station by Bob Yin
    http://www.youtube.com/watch?v=TOC2Qc2Qedw

    Symbiosis: Cleaner shrimp and Fish Clients
    http://vimeo.com/1997771

  9. # 5 MathGrrl
    The working link for a free PDF is:

    http://www.ncbi.nlm.nih.gov/pm.....315903.pdf

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