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Author | Topic: The Great Debate: Molecular Population Genetics and Diversity in Evolution | |||||||||||||||||
Faith ![]() Suspended Member (Idle past 680 days) Posts: 35298 From: Nevada, USA Joined: |
OK, which particular two?
1) You haven't proved this happens 2) How does mutation choose to change only some loci and not others? 3) Even if it did happen, managing not to affect the salient characteristics of the breed or species, it doesn't change the fact that to get that breed or species required the loss of genetic diversity for those evolving new traits. THAT is where the changes are occurring, the new phenotypes and the loss of diversity. Of course it MUST occur throughout the genome anyway just because reduced numbers has to bring about a change in gene frequencies wherever in the genome this can happen, and that in turn has to bring about the loss of genetic diversity I'm talking about. Etc etc etc 4) It also fails to add diversity where the ToE would need it if further evolution beyond any species really were possible -- in those traits that most clearly characterize the breed or species. That is, net diversity that leaves the new species intact doesn't help the ToE at all. Blurring the species with mutations destroys evolution, and so does leaving the species intact, with or without increased diversity. But of course overall decreased genetic diversity is what brings evolution to a natural stopping point. 5) Since apparently Sardinia had lots of gene flow over the centuries although your referenced study said it didn't, and the elephant seals are also still considered to be genetically depleted despite their great increase in population, although your study there said their genetic diversity had increased, I'm beginning to wonder how good all those supposed markers of genetic diversity in those studies really are. Microsatellite information for instance. Mitochondrial information for instance. What do you really learn from those things about the organism's overall genetic diversity? Edited by Faith, : No reason given. Edited by Faith, : No reason given. Edited by Faith, : No reason given.
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Faith ![]() Suspended Member (Idle past 680 days) Posts: 35298 From: Nevada, USA Joined: |
(Great Debate)
I'm wondering more and more just how good this "evidence" is that mutation is a major diversifying force. I mean there is something wrong with your evidence in relation to Sardinia and the elephant seal, and there is also something wrong with the study Tangle came up with for mutation as the cause of the change from the light to the dark peppered moths. I presented my objections to that on his thread but will repeat them here because I'd really like your response to this:
Also seems to be the case with many other studies that find mutations to be the cause of genetic changes. Edited by Faith, : No reason given. Edited by Faith, : No reason given. Edited by Faith, : No reason given.
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Faith ![]() Suspended Member (Idle past 680 days) Posts: 35298 From: Nevada, USA Joined: |
Just so you know, I am still working on your post although also being distracted. I hope it's not a problem breaking it up into small bites; it seems to help me get my responses organized. But I'm working on a bigger bite next time. I'll post it in this box.
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Faith ![]() Suspended Member (Idle past 680 days) Posts: 35298 From: Nevada, USA Joined: |
I'm sorry to inform you that this is not exactly "A Scientific Debate" as I am not a scientist and not required to be one to debate at EvC. Scientific American ought to be an acceptable reference, and whether you accept it or not I'm considering it so for purposes of this discussion.
Nobody has explained to me what either haplotype or nucleotide diversity has to do with anything, what it actually is, why I should regard it as more important than the usual measures of genetic diversity. But I think I get some idea from this post.
So what I'm getting is that you get a lot of mutations at these locations. I understood that to be the case for MtDNA, which is the "haplotype" DNA, but the import of that wasn't apparent at the time. The fact that you get these mutations at this location you call an increase in genetic diversity, which technically of course it is I suppose, but I have no idea why it should be taken as any kind of measure of the genetic condition or general health of the seal population. What does this DNA do anyway? It seems to do nothing more than accumulate mutations. Does it do anything else in the organism? I can see why accumulating mutations so frequently could make cytochrome C a good marker of species since each would get its own mutations, and cytC has something to do with MtDNA, sorry I forget exactly what and I don't want to abandon my post to go find out. Perhaps you will explain if that haplotype DNA actually DOES something. Because if it doesn't, if it does nothing but accumulate mutations, I don't see what it has to do with any kind of genetic diversity that would benefit the elephant seal. The kind of genetic diversity that is needed is the kind that makes traits, phenotypes, changes in the animal itself that can benefit it by giving it options for variation, without which it remains in danger of extinction. THAT kind of genetic diversity is measured by heterozygosity: the more homozygosity the more endangered the animal, which is the problem for the cheetah as well as the elephant seal. Homoygosity at the loci that most characterize the animal used to be the criterion for a purebred until it became known that it put the animal at risk of genetic diseases. All this goes on in the genome where genes make phenotypes. What does MtDNA do? I don't have a clear idea about nucleotide diversity except that it implies a change in the sequence of a gene, which would of course be the result of mutation. Mutations aren't very often a good thing so I don't see how this "increase in genetic diversity" bodes any good for the seal anyway. Since nothing is said about how it relates to the measure of heterozygosity I've always taken as the indicator of true genetic diversity, I'm going to assume that these mutations are generally bad for the seals and it's just a bit of word magic to call them an increase in genetic diversity as if they solved the poor creature's plight of genetic depletion. This of course means I'm saying some unkind things about scientists which I'm sure you'll take with your usual indignation, but really you should just take it as a reason to explain why I should regard this evidence as answering my argument that normal evolutionary processes lead to decreased genetic diversity.
Yes you would have to be right about this. But nothing in these studies shows that either of these sources of increased genetic diversity is REAL increased genetic diversity that gives the genetically impoverished elephant seal any more genuine opportunities for further variation than it had before. I believe that Scientific American blog you so haughtily dismiss as unworthy of your scientific consideration is right: the elephant seal remains genetically endangered even with all this bogus increase in genetic diversity. Now, an increase in viable heterozygosity -- THAT would be SOMETHING. Edited by Faith, : No reason given.
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Faith ![]() Suspended Member (Idle past 680 days) Posts: 35298 From: Nevada, USA Joined: |
After answering the post about the seals maybe I just got an influx of cynicism but it hit me that what's being measured in both these studies has nothing whatever to do with REAL genetic diversity. MtDNA has nothing to do with anything related to normal evolution of traits so its accumulating mutations is just the usual accumulation of garbage, which is what most mutations are, nothing that could possibly contribute to the health of any organism or human being. It's kind of like the logic of someone needing to measure the dimensions of a whole apartment who decides just to measure the broom closet because it's easier and it also is measurable in feet and inches just like the whole apartment so it should suffice as a measure of the apartment. Of course it's absurd but that's how it hits me. MtDNA has nothing to do with the evolution of traits that I've been talking about so how can it have anything to do with increasing the diversity that is lost through that process? So you've got increased MTDNA diversity, which is nothing but a bunch of meaningless mutations absolutely unrelated to the genetic diversity that is lost in the evolutionary scenarios I've been describing. I realize this is too absurd to be true but I have no other way of making sense of this. So this is your next project: proving me wrong about this. Edited by Faith, : No reason given.
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