Evolution Requires Reduction in Genetic Diversity

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Oh brother. You are NOT following the argument. The POINT was that they HAVE to be selected to come to any kind of expression in the new subpopulation, or in genetic drift where they are for that matter. ou are NOT following the argument. To figure in the situation I've been describing forever here THEY HAVE TO BE SELECTED

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Disagreeing with claims that are obviously wrong does not indicate a lack of understanding. A dominant allele will obviously make it's presence in the population known, whether it is selected or not. Genetic drift is changes in allele frequency without selection.And, the extreme case of the founder effect is the best case for alleles become fixed through drift alone....

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How does evolution arrive at what is called a new species? I know only one way: by forming daughter populations that bring out new traits or phenotypes because of their different allele frequencies, and a series of such population splits would get there sooner. And this process requires reduction in genetic diversity, variation or whatever the proper term is.

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Nothing has been said to indicate that there is any other way for speciation to occur.

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In fact it has been suggested that mutations are often required to reduce interfertility. Which seems more likely than your scenario.And, of course, we must not focus only on speciation events. We must recognise the increases in genetic diversity that occur at other times.

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Adding genetic diversity to a population by any means at all, migration or mutation or whatever, adds new phenotypes but doesn't do anything to make a new species out of them.

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Aside from being the likely cause of infertility between populations...But even if that were entirely true, what would be the relevance ?

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It doesn't matter if the diversity is added to a large population that subsequently splits, or if it is added at the end of a series of populations, to a subspecies or new species, the same process has to occur for the formation of further species: reproductive isolation of new traits breeding together, and that will reduce genetic diversity (the number of allelic possibilities)which makes further evolution impossible. So you get new diversity and the same thing has to happen and around we go. Evolution, meaning macroevolution, meaning evolution as understood by the Theory of Evolution, really is impossible.

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And this is obviously fallacious. If you bother to think it through it can easily be seen. For the argument to work it must be assumed that the reductions in genetic diversity are permanent. That no species can ever have as much genetic diversity as its parent species. But that is just an assumption, and an assumption that is very likely false.

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I do think that is obvious if you just think it through.

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Then I can only suggest that you do take the time to think it through, and pay attention to the responses you've gotten. Because if you did you'd see that it is NOT obviously true, and is in fact very likely false.

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Evolution in action is therefore ONLY microevolution, and it has a natural end point brought about by the loss of genetic diversity (or allelic possibilities) necessary to the creation of new phenotypes. If this leads to "speciation" it also leads to genetic depletion, which makes further evolution impossible.

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And that is still only your assumption. And given that the evidence is still against it, I see no reason to accept it.

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But if speciation is not really a new species but just a subspecies that has lost the ability to interbreed with other subspecies, and if as a matter of fact it possesses reduced genetic variability, then it is sheer illusion to call it speciation.

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Faith, I understand that it is important for you to refuse to accept that you believe in macroevolution - independent of the actual meaning of the word. But in doing so you only betray the fact that you are the one who believes in word magic.But saying that your irrational hate of a word dictates the correct usage of other words - even to call a correct usage "sheer illusion" is the height of arrogance. That is, even if your description was entirely correct for any single example it would still be a new species.And, of course, through genetic drift alone an isolated population will certainly accumulate genetic differences at the level of sequences. And, over time, it is very likely that it will acquire new traits through mutation too. It is even likely that these changes are the cause of the inability to interbreed with the parent population.

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Which is not based on any kind of evidence of relatedness between the different groups but is only an appealing mental construct imposed on the facts.

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The nested hierarchies ARE facts. Facts you don't like. But simply making assertions will not overcome facts.

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And they do, through normal microevolution as I've been laboriously describing it, which reaches a natural end point where macroevolution should begin but can't because of genetic depletion.

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I think you've repeated your assertions often enough. But that is hardly a convincing argument. You need evidence. You need to deal with the objections. You need alternative explanations for the evidence for large-scale evolution rather than trying to pretend that the evidence doesn't exist. If all you can do is to keep repeating your assertions then you don't have a case.

Faith, we understand your opinions. We just don't agree with them.What you are really saying is that you have to keep repeating your opinions because you can't support them.

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the environment weeds out unproductive changes.

Pure ToE, purely hypothetical. If this really happened in reality nobody would survive.

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So now you're rejecting natural selection ? Unfortunately for you natural selection is a fact. And a fact that is the basis of your argument anyway.And since natural selection is a fact, it must be your assumptions that are at fault. Very likely your dismissal of the idea that mutation counteracts the loss of genetic diversity caused by selection.

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I've acknowledged that natural selection occurs in some cases (peppered moths for instance) but at the same time I've argued that I think it is far less often the cause of adaptive changes than mere reproductive isolation of a randomly assembled smallish daughter population.

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So you agree that it is NOT "purely hypothetical" as you claimed. And so far as the rest of your claims go, are you REALLY relying on drift to get all your "loss of genetic diversity"?

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I've argued this in relation to Darwin's finches for instance, and the large-headed lizard on the island in Croatia.

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Have you even read the popular literature in the studies of natural selection with regard to Darwin's finches? If you haven't, isn't it your position that is "purely hypothetical"?

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Everything I've seen about the cheetah is that it was formed by a bottleneck, a purely random and not health-promoting event. The best interpretation then seems to be that its wonderful body design for speed was also purely accidental or random.

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False. Everything you,ve seen about the cheetah's genetic problems is attributed to the bottlenecks. That's not the same thing at all. You haven't seen anything supporting the idea that the cheetah's speed is "purely accidental or random".

There is no "also". You accepted that natural selection does occur. Calling it "purely hypothetical" was a stupid lie. Because how else can we characterise a statement that you knew to be false and that seriously undermines your already-weak position?And, since you haven't bothered to look at the evidence you really aren't in a position to judge which hypothesis is better even in particular cases. And there's no excuse for that when there has been a long-term observational study and even a well-known popular book about that study. As is the case for Darwin's finches.

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You don't know if it's false or not, you just enjoy saying so.

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I have good reason to think that you have never seen any source making that claim. If you want to say otherwise produce one.

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If new traits are the result of mere change in allele frequencies, the cheetah's characteristics would be the result of the bottleneck which just happened to "select" the alleles for its sleek fast body type.

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That's hardly a rational argument. How can you tell the difference between traits existing before the bottleneck and those that only appeared with the bottleneck?

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As usual we're arguing plausibilities here, not evidence. There is NO actual evidence I've seen for any of the ToE's Likely Stories either.

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What your sources say should be a matter of fact. For the cheetah if your only argument is that you find it plausible you don't have much of a case. It's only plausible to you because it fits with your assumptions.Anyway, if you want to tell us that bottlenecks produce major adaptive change why not talk about elephant seals? The major bottleneck there is in historical times, so surely it's a better chance for you to produce evidence.

This thread is supposedly about your ideas. If you can't produce evidence to support your claims, too bad. If you chose not to look at easily available evidence before speculating - and expect your speculations to be accepted as fact - then you are just being silly.So, your claim that natural selection is "purely hypothetical" is false and you knew it to be false when you made the claim. The fact that rejecting natural selection also severely undermines your own position is a relevant point in the discussionAnd in fact let me ask you - if I argued more like you - but preferring my own beliefs rather than yours- would you be more likely to believe me or less ? I grant that I would have to say more things that are actually true, but I hardly think that you would admit to finding that a reason to disbelieve me.

So, since you haven't replied I think we can assume that I was correct. That your claim that

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Everything I've seen about the cheetah is that it was formed by a bottleneck, a purely random and not health-promoting event.

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is based on nothing but your own wishful thinking. Not one source, not one piece of evidence, not one argument beyond your own assumptions.But your whole argument is based on the idea of drift producing adaptive change - and idea rightly rejected by biologists because it relies too heavily on chance. A desperate and irrational need to deny any significant role for natural selection in evolution is not a good reason for overturning that judgement. And anyone who really cared about the truth would agree.

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I'm not comparing breeding and microevolution in the wild on the basis of selection, but rather on the basis of the effect of a population split. There may or may not be selection involved.

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Then it seems that you are attributing too much to the population split and not enough to selection. Breeders do not take a random pair and simply let their descendants breed randomly. Selection is a vital part of the process from the very start. While you may see some recessive traits come out without selection it should be slower, less likely to show the degree of difference seen in artificially bred populations and less certain.Also we note that, excepting the more extreme differences of size, to the best of my knowledge, reproductive isolation must still be artificially maintained in every domestic breed of animal. If even the extreme case of artificial selection does not produce populations unable to interbreed how can we be sure that it will happen in nature without some other factor?

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Well, since you are ridiculously wrong that I've ever made any claim that mixing old alleles could create a genetically new species, ---HOW UTTERLY RIDICULOUS

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Either you are splitting hairs here or you are admitting that mutation is necessary for speciation. Without mutation all you gave is "old" alleles and every combination of alleles is a mix of alleles existing in the parent species - a mix that could have existed in the parent population.

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I've given plenty of examples where it's observed.

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No. You can't give any examples where it's been observed to happen. Simply examples where you assume that's what happened. That isn't the same thing.So, the question is why can't you show that that happened. Why can't you point to new features in elephant seals, since they are one of your chosen examples and where the bottleneck occurred in historical time. Surely they should be a perfect example.

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Where what has been observed to happen? Since you go on to the bottlenecked seals it's clear you have something completely differe3nt in mind than I've said.

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If you bothered to check the context you would see:

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To ask that question means you don't understand anything I've said.

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You don't think that a loss of alleles followed by drift produces new "species" ?

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I don't expect the bottlenecked seals to recover

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According to stated your views recovery would *inhibit* the appearance of new features. Is this an admission that in reality you think that new phenotypic features are usually produced by mutation ? Or is it the case that your objection is based on not reading what *I* wrote.