The End of Evolution By Means of Natural Selection

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This is the answer that is always given to this argument, and Pink Sasquatch gives another version of the same answer in her post that follows PaulK's. I answered in turn many times that increase in variation (sometimes called "information") doesn't prevent this ultimate reduction -- you can have as much variability as mutation or any other source of genetic variability can provide, but the processes that select and isolate, which are considered essential to evolution, inevitably work to reduce the needed genetic variability, and this spells the end of evolutionary processes. It seems to be generally overlooked that for evolution to occur, alleles must be eliminated, thus reducing genetic diversity.

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This response really makes no sense. If there are increases in variation and decreases in variation the net change in variation will be the difference between them. Only if the decrease is greater than the increase will there be a net decrease in variation. This is simple, obvious fact and flatly denying it is pointless.

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This isn't a simple addition and subtraction problem.

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At heart it is. Granted there are complications in the details, but there is no doubt that there is addition as well as subtraction.

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If you start with twenty alleles in a population for one gene and one of them becomes crucial for a particular environment and therefore gets selected, either rapidly or slowly depending on the selection pressure, you will lose the other nineteen alleles as the one selected comes to determine this particular trait.

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And that allele will still be subject to mutations and new alleles will be derived from the one survivor. Meanwhile other genes will also be mutating, producing new alleles. There is addition as well as subtraction.

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It would make no sense to add new alleles for that trait either, as it has been selected because of its value for the species. Selection REQUIRES the elimination of alleles. Addition would only kill selection and kill evolution. Addition means stasis, not evolution. Selection (or isolation of a portion of the population) is essential for evolution to occur.

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Addition certainly does not mean stasis. It cannot, because addition is the arrival of new alleles, not previously existing in the population. That is an example of change, not stasis. Selection gives direction to change, making it more than a random walk but mutation and drift ensure that change would happen, even in the absence of selection.

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But the variation is rebuilt during succeeding generations.

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I bolded that statement because I believe that is wishful thinking that is not borne out in reality. If this were true conservationists wouldn't be wringing their hands over the small numbers of salmon that get themselves up a tributary where undesirable reproductions bring undesirable traits to the fore along with extremely reduced genetic possibilities for further change; and there wouldn't be a club for the preservation of the cheetah. While all along in this discussion I am assuming for the sake of argument that useful mutations do occur at a rate that allows them to become the basis for selected traits, in reality this simply doesn't happen, as all too many conservationist scientists in the field ought to be able to testify.

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I am afraid that you don't know what you are talking about. Severe bottlenecks cause serious problems. The species is liable to go extinct before genetic variation can recover - especially if the population remains low - and THAT is what the conservationists are worried about.In fact the cheetah disproves your argument because its genetic variation IS recovering: Dating the genetic bottleneck of the African cheetah (Abstract)

If there is addition as well as subtraction you have to show that the subtraction outweighs the addition. That's simple fact.

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How unfortunate! This poor allele was selected only to be morphed into something else after doing its duty for the species? Wouldn't the adaptive benefit its selection conferred on the population then be lost again? What kind of "evolution" is going on here?

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No, that's not necessarily true. There must be plenty of variations that would not compromise the adaptive change. Some might build on it further, some might confer some other benefit - possibly where the protein is used in some other role entirely - and a lot will just do nothing. Given the facts that proteins often have multiple uses, that neutral mutations are common, that much of the structure of a protein is not critical to it's function the assertion that any additional variation will disable an adaption seems hard to justify.And, of course, in some cases the fixed trait becomes unnecessary and can be lost.

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Indeed there is, but what is going on in the rest of the population is not my subject here, as I'm trying to keep the focus on what happens when there is SELECTION and ISOLATION, not increased variation.

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You cannot consider variation without considering a population. And you can't ignore increases in variation - they are a critical factor in your argument. Maybe you think that I'm talking about the case where a subpopulation is split off and becomes a new species - and that I am counting both the variation in that population and in the remaining parent population. But that would be completely incorrect. Others are making that argument, not me. Did you forget that species have many genes ? Or that genetic variation must be considered over the whole genome, over a population ?

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What you get from mutation is the raw material for evolution, you do not get evolution. Any number of writers on this subject will tell you that, especially Dawkins I believe. I suppose I should look it up at some point.

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I have no idea why you find the need to tell me something that I already know. Nothing in my post disagreed with this in the slightest. You must remember that your whole argument is based on assuming that the supply of new variation must be inadequate.

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You need to find solutions consistent with both your religious views *and* reality.

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But Percy, her argument isn't even consistent with her religious views. Even if the animals on the ark were modern species rather than the "kinds" preferred by most YECs, every species would have suffered a bottleneck. And according to Faith's argument they cannot recover from that. YECs need a mechanism to generate variation even more than evolution does to explain why we don't see evidence of that bottleneck.This point was brought up in the original discussion so Faith has no excuse for ignoring it.

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I don't know if increased variation in mitochondrial DNA and hypervariable minisatellite loci contribute to the genetic diversity needed by the cheetah to recover or not. It isn't the normal expected source of genetic diversity so you'd have to tell me what it means.

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The reason for looking at the most variable regions is that those will show the greatest change - which is helpful for dating a relatively recent bottleneck.I have no idea what distinction you are trying to make, though. It's a clear case of mutation increasing the diversity, and there is every reason to expect increasing diversity in other genes as well. Any claim that this is not happening and cannot happen needs real evidence - not simply an assertion. Especially when that it IS happening to some genes.

Bottlenecks and reduced genetic diversity are a major part of this topic. So that fact that your beliefs include major bottlenecks in many species, a belief contradicted by the existing genetic diversity - and if your arguments only make this problem worse for you it seems to be clearly relevant. Even if it merely highlights a major inconsistency in your own beliefs, it shows that you have not clearly thought things through since the previous thread, even though the issue was one that had been raised. And if you have not managed that then I suggest that a little less certainty on your own part might be appropriate. Other Bible-based beliefs can be discussed elsewhere.

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I don't really think in terms of recovery, because bottleneck is just one way I see new species forming

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Neither the severe bottleneck in the cheetah's past, nor the bottlenecks that would afflict the species in the Ark - if the story were true - are examples of speciation. And, as I pointed out, the typical YEC view involves multiple speciation events after the Flood to produce a wide array of modern species from a single "kind".We do not find evidence of the many severe recent bottlenecks implied by the Flood story - and both your ideas and the common YEC idea of ancestral "kinds" occupying the Ark only make the situation worse. Unless you abandon the Flood story altogether you need to explain why genetic diversity is far HIGHER than it should be in every species that should be affected.

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I assume enormous genetic diversity in the passengers on the ark, that has since played out in the many splittings and variations and speciations we see today

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You cannot have "enoromous genetic diversity" in a single pair. You can only have a maximum of 4 alleles for each gene. That is quite basic genetics.

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This is a complete misreading of what I'm doing and I'm at a loss how to correct it since it keeps cropping up. I am NOT "assuming" this at all, and my argument is not "based on" it. It is an OBSERVATION that the selecting-isolating factors determine the phenotype of a new subpopulation by reducing its genetic diversity.

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Since your argument asserts that evolution will end, and since it will not end if diversity is replenished I cannot see why you call it a "complete misreading". Even if we assume that your "OBSERVATION" is completely and entirely true it cannot stand alone as an argument against evolution.

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Oh I can't get this said in any way that you aren't going to continue to object to in the same old way so I have to find new waysto say it

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Here's how you could say it so that everybody will get the point. "I was wrong. Evolution will not end. The supply of new variation means that evolution can continue indefinitely."

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In domestic breeding -- let's stick to dogs -- do you agree that you get and maintain a breed by being sure you breed it with its own type?

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Do you agree that this is to protect the breed's particular allele complement from contamination from alleles of other dog types?

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I'll agree with those two.

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Do you agree that any dog breed possesses a very limited genetic diversity with respect to the total dog population?

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I can't agree with that without evidence. THere is no reason why it would have to be the case. There are a lot of genes and relatively few are likely to be involved in the desired traits.

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Do you agree that it is its limited genetic diversity that is the basis for the characteristics of the breed itself and that if there is any increase in the genetic diversity the breed will lose its character at least to some extent?

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I agree that distinctive traits are maintained by fixing some alleles. I can't agree that any increase in genetic diversity would affect the distinctive character of the breed. In fact I cannot imagine why any informed individual would think that. Only mutations that affected the distinctive traits of the breed would have that effect and it would be absurd to say that all mutations would do so.

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Do you agree that Darwin based his natural selection on domestic selection?

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To an extent. In this case I should emphasise that Darwin did not assume that natural selection would typically include the intensive inbreeding used to accelerate the fixation of traits.

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Do you agree that natural selection is the "engine of evolution?"

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I would say that it's more like the steering. Natural selection is what enables adaptive evolution, by providing a degree of direction. Without a source of variation, it will eventually stop.

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Do you agree that the end goal of evolution is speciation or is evolution simply any change at all whether it ever leads to speciation or not?

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Absolutely not. Evolution doesn't have an "end goal" and speciation is not in any way a goal of evolution. (It should also be noted that there is only limited evidence that natural selection directly favours speciation at all, and then only in cases where the populations are actually interbreeding).

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Well, maybe you'll get the point and maybe you won't. It isn't a simple additive process. The subtractions that lead to speciation lay waste to all the additions you can come up with. That's the idea anyway. Prove that there's an increase in genetic diversity AT speciation. Simply claiming that mutations are going to prevent the reduction I'm talking about doesn't cut it.

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Simply claiming that the reductions of diversity involved in speciation - to the extent there are any - MUST outweigh the additions from mutations doesn't cut it either. You need the numbers. Which is exactly the problem your last argument ran into.And no, we don't need to show that there is an increase of diversity at speciation. Because speciation events don't happen that frequently. If it happens that a new species should happen to have a slightly reduced genetic diversity compared to the parent population it doesn't matter, so long as diversity recovers in a reasonable period.Again, the evidence doesn't show that there is any serious problem with a loss of variation. Your favourite example, the domestic dog, shows plenty of variety. So do pigeons, an example used by Darwin.So, do you have a GOOD reason for discounting mutations ? Because you haven't come up with one in this thread, even though it is the major issue from the last thread.

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Kinda the same way Dawkins would be convinced of the falseness of evolution if a rabbit were found in the precambrian, which is the opposite of what creationism would predict too.

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Of course that is completely wrong. Even modern (young earth) creationism would predict that the something of the same "kind" should be at least possible in pre-flood sediments. And the quote you refer to is usually attributed to Haldane who died in 1964.YEC does not attribute all fossil-bearing strata to the Flood, assuming that some come later. Since these must have formed in the ~4000 years since the Flood there seems to be no problem with fossils being formed in the ~2000 years prior to the Flood. Especially as they will have more time and better conditions.And since YEC has no adequate explanation for the order in the fossil record at all, it can't really be said to make predictions even of the order in the rocks that they do attribute to the Flood.Also, let us be clear, that the quote is usually described as an off-the-cuff remark. We should expect rather more from you than that, if you have really seriously considered the idea. For instance if you actually think about it Haldane had the problem that large amounts of evidence had already been examined and found to support evolution, You, on the other hand have no significant evidence at all - just theoretical musings and guesswork. Your ideas are merely a hypothesis awaiting testing (at best), not an established theory - therefore at the stage where a scientist would be seriously looking at how it could be falsified.

That is absolutely true, and I considered it. However Faith could simply argue that she was only looking for something that would falsify her claims and wasn't considering evolution. While that would be a dubious move (since she is trying to argue directly against evolution) it would be far from the least rational argument that she has used and not absolutely without merit (just very, very little).

Some points you need to consider:We have evidence that the variation in the dog population has been increased by mutation.
(The short legs seen in dachshunds, referenced earlier in these threads).Faith's model requires that variation is continuously decreasing. Showing that there is plenty of variation within modern species isn't exactly helpful to her view. (The more so when you consider that she believes in a literal version of Noah's Flood. I would suggest that Faith's model is in serious conflict with her YEC views, and in fact only make sense if OEC is assumed).There doesn't seem to be any great need to challenge Faith's model of speciation beyond the fact that in real speciation as opposed to dog breeding the timescales are extended so that mutation plays a greater role (it is likely required if reproductive incompatibility is involved) - remember that for dogs we are talking about the time to establish a new breed, not the whole of the domestication period. It also likely does not involve the same level of inbreeding. However, if mutation can restore the diversity of the species over its lifetime then Faith's argument has failed. (It should also be pointed out that natural selection - unlike dog breeders - does not directly care about maintaining the distinctive traits of species - if a trait gives a reproductive advantage it will be selected, if not it will not be selected.)Faith's speciation argument seems to be based on the idea that each speciation fixes alleles (which cannot then change at all) and eventually the lineage will run out of genes that could be fixed. The problem is that fixation is defined as including variants of the allele produced by mutation - which means that the allele can be changed, and a new version fixed. Also genes can be added and traits can be lost as well as gained. So the argument as Faith has outlined it is not a sure thing at all. Faith needs to quantify her argument to show that it actually works.

I think you are confusing the allele with the trait. Black fur is a trait. The form of the gene that causes black fur is the allele.I think that the dominance of the gene is not even relevant for considering the incidence of black fur. There might be a small recovery in the next generation because rabbits homozygous for the black fur allele will have only black-furred offspring, but that's all I can think of. Without selection, it's down to drift.

This is exactly the situation I presented in my post. You are starting with rabbits homozygous for the B allele and thus the incidence of the black-fur trait increases - but only for one generation (and it decreases in the next).However the relative frequency of the B allele does not increase. The number of copies of it doubles with each generation but only because the size of the population doubles in each generation. And that is all that is happening. Therefore after the initial increase (due only to the assumption that the surviving black rabbits are homozygous for B) the proportion of black rabbits will not increase either.