Iridium Nightmare and Living Fossils

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Originally posted by ksc:
The living fossils SHOULD have evolved. They didn't.

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How do you know they didn't?Your are equating morphological change with evolution as a whole, evolution is the change in allele frequency over time & doesn’t necessarily a mean morphological change. Alleles may have been lost, gained, neutral mutations fixed & lost, even chromosome number & composition changes, all without major morphological change. This is all evolution, if the ceolocanth is morphologically well adapted to it's environment, then anything that changes that will be negatively selected against, maintaining the status quo.Mark------------------
Occam's razor is not for shaving with.

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Originally posted by ksc:
I really enjoyed reading the evo responce. For all you out there this is it in a nut shell

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"No one says animals have to evolve."

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Funny though, even the evo logic dictates that they do.

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No, it doesn't.And what evolutionary biology book says it does? Nevertheless, as I have shown, & Quetzal, Edge, Mister Pamboli has alluded, evolution does not necessarily equate to physical/morphological change. So, what is your evidence that the ceolocanth hasn't evolved?

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Originally posted by ksc:

In my post I presented an example of evolution they tell us occurred, (wolf to whale)

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No evolutionist told you wolves evolved into whales, artiodactyls, yes, wolves, no. Straw man.Mark------------------
Occam's razor is not for shaving with.

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[This message has been edited by mark24, 05-07-2002]

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Originally posted by ksc:
mark24: Actually, the coelacanth did evolve somewhat and it is not clear that modern versions would actually be the same
species as the Cretaceous coelacanth by some definitions. Nevertheless, there is no part of evolution that says an
organism must evolve. If you think differently, then produce evidence to that effect.

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The fossil record. Sheeze, even dogs show more variation than the coelacanth.

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Not really, as Mister Pamboli points out, earlier species of coelocanths were much smaller than the 2m specimens today. But even if this weren't true, so what? You still haven't shown me that coelocanths haven't evolved. For the third time, don't equate evolution with purely morphological change. Can you show me that coelocanths didn't evolve?Mark------------------
Occam's razor is not for shaving with.

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Originally posted by ksc:
mark24: Actually, the coelacanth did evolve somewhat and it is not clear that modern versions would actually be the same species as the Cretaceous coelacanth by some definitions. Nevertheless, there is no part of evolution that says an organism must evolve. If you think differently, then produce evidence to that effect.

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The fossil record. Sheeze, even dogs show more variation than the coelacanth.

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Karl, I don't know who you're quoting here, but it ain't me!You actually are claiming to answer a question I never asked. Bearing in mind you are claiming to Percy to have answered my questions, & are seeking an apology from him. Can I have one too?I’ll ask my question again. How do you know coelacanths didn’t evolve?I repeat. Evolution is the change in allele frequency over time, & doesn’t necessarily mean morphological change. Alleles may have been lost, gained, neutral mutations fixed & lost, even chromosome number & composition changes, all without major morphological change. Genetic drift can take alleles to fixation if they are neutral, or nearly so. If that drift affects a morphological change that affects survival negatively, then NS will act upon it. As has been pointed out to you, in the relatively stable deep sea environment, the coelacanth would have reached a morphological optimisation a long time ago. Any morphological changes will therefore affect fitness in a negative way. The only real way that these mutations will be positive (or even neutral) is if that environment changes significantly.Mark------------------
Occam's razor is not for shaving with.

ksc,You still haven't told me WHY long time frames equate to morpological change. I refer you back to message 46.Mark------------------
Occam's razor is not for shaving with.

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Originally posted by ksc:
Yeah, your right mark24. After 340 MY, and all of the mutations that according to the evo theories would have occured along with the normal 340 MY of genetic drift, along with a change in the tempo of evolution, yeah, your right. They should still look the same. My bad. sorry.

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Good, glad you accept normalising selection acting on non-neutral mutations affecting morphology. You seem to be labouring under the misapprehension that genetic drift overides NS. & your right, it is your bad.So, for the umpteenth time, can you show me that the coelacanth didn't evolve?And you have the gall to ask for an apology from Percy because you answered questions? I think not.Also, what particular change in tempo of evolution are we talking about? More mutations? Higher level of morphological adaption? Are you SURE the coelacanths experienced this? Are you SURE their environment changes in such a way as to REQUIRE change?Please answer these questions rather than just reasserting points made in your first post.Mark------------------
Occam's razor is not for shaving with.

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Originally posted by ksc:

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Good, glad you accept normalising selection acting on non-neutral mutations affecting morphology. You seem to be labouring under the misapprehension that genetic drift overides NS. & your right, it is your bad.

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So, for the umpteenth time, can you show me that the coelacanth didn't evolve?

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...perhaps you should have followed the coelacanth post I presented.

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Originally posted by ksc:

Now why are you fibbing? The question was answered and it was answered in more than one way. Sheeze mark, go read the post then get back to me.

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Then answer the question. It’s a simple cut & paste job, after all. Silly ol' me can't see where you answered this precise question in context of genetic variation, (which, if you check, WAS the context). I’m very interested as to how you know such details as chromosome number & structure of cretaceous coelacanths, not to mention amino acid/nucleotide sequences of proteins/genes. Have you shown that coelacanths never evolved?I hope this isn’t going to turn into one of those kidnician postings (creationweb), where you continually maintain to have answered questions, but actually haven’t.Paste away.

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Originally posted by ksc:

Also, what particular change in tempo of evolution are we talking about? More mutations? Higher level of morphological adaption? Are you SURE the coelacanths experienced this? Are you SURE their environment changes in such a way as to REQUIRE change?

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Please answer these questions rather than just reasserting points made in your first post.

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Why don't you present some evidence from a text book that says things don't have to change instead of the evobabble you have been presenting.

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From Futuyma, Evolutionary Biology, p344-5. In describing Dhobanskies experiments with Drosophila pseudoobscura . The critical implication of this experiment is that the chromosome frequencies approach STABLE EQUILIBRIUM, no matter what the initial frequencies are. This can only be due to natural selection, FOR GENETIC DRIFT WOULD NOT SHOW SUCH CONSISTENCY. Moreover, natural selection must be acting in such a way as to MAINTAIN VARIATION; it does not necessarily cause fixation of the single best genotype."Figures are provided showing the equilibrium being reached over TIME, regardless of initial variations introduced. Natural selection is acting to maintain variation, IN SPITE OF GENETIC DRIFT.Your question was to give a textbook quote as to why things don’t have to change. Answered. Can you give one that says they do?

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Originally posted by ksc:

So i have to now assume that you and joey both teach that time and mutations DO NOT produce change. especially 340MYs worth of mutations.

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Nope, I'm sure time & mutation does produce change. This is the point of my question, above. Positive adaptations may well have taken place, just not on the morphology of the coelacanth. Probably many neutral mutations have been fixed/reached equilibrium, via drift. However, those mutations that affected the basic body plan would be deleterious, & acted on by ns. Stabilising selection, no less.Can you tell us why stabilising selection cannot act over 340 m.y.?Mark------------------
Occam's razor is not for shaving with.

Percy,Thanks for the information. I understand that kscs position is that the ceolacanth has remained unchanged for 340 m.y. The point I'm picking up upon is that just because species are morphologically similar, doesn't mean they are genetically similar. So, assuming common descent, a 1m long cretaceous ceolacanth may have a very similar bone structure to Latimeria chalumnae, doesn't mean that it is genetically the same. Namely, that evolution has acted upon & changed the genome, whilst retaining the same morphology via stabilising selection.Karl has asserted that todays coelacanth is virtually unchanged, & that evolution hasn't acted upon it. Until he can show this to be true, he really doesn't have an argument. The best he could attempt is to try to demonstrate that there is no such thing as stabilising selection.Note that he hasn't answered......1/ Can you tell us why stabilising selection cannot act over 340 m.y.?2/ Can you show, in a genetic context, that the coelacanth didn’t evolve?If he can show that stabilising selection can’t work over 340 m.y. (& I understand that modern coelacanths aren’t the same species as their fossil ancestors, also that is the basic body plan that has been preserved), then he has a point.If he can show that evolution in it’s broadest sense hasn’t occurred (loosely, SINES, LINES, pseudogenes, retreoviruses etc.), then he has a point.Until then, he can’t claim victory because the very assumption that he bases his arguments upon can’t be shown to be true. ie The coelacanth hasn't evolved, & that there isn't a mechanism that prevents change.Mark------------------
Occam's razor is not for shaving with.

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[This message has been edited by mark24, 05-12-2002]