Natural Limitation to Evolutionary Processes (2/14/05)

Isn't that the field known more commonly as "bioinformatics"?

I take a slightly more kinematic than dynamic approach of PaulK so I think it is possible that limits on selection can keep evolution "afloat" even if the zero state be approached. This however is only my own idea and I am having a bit of a problem trying to figure out how to join in in this thread plus my own notes on the relevant issue is not immeidately available to me. I found it quite strange that Will Provine would ask Phil Johnson "what are the limits on selection" when he didnt have reason to think there might be any from breeders' knowledge. I have started to imagine such limits given the "interference" macrothermodynamics has been postulated to hierarchically inlay between boundary conditions Salthe elsewhere philosophized on. The issue I might assist however is on drift as there seems to be a real difference of opinion between Wright and Fisher AND Mayr on that. That is not possible.

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The processes of variation (called "speciation" by evolutionists) proceed by selecting out portions of the built-in potential for expression in the phenotype. The process ALWAYS involves reduction of the frequency of alleles and of genetic variability because for new traits to come to the fore new allelic combinations are required and you don't get these unless other allelic expressions are somehow suppressed -- or unfortunately in some cases actually killed.

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The process of natural selection works on the phenotypes. This can cause a reduction in variation but you mustn't forget that there is still hidden variation within the genotype which can continue on in later generations and not be expressed.

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Not "can" cause a reduction, but natural selection ALWAYS causes a reduction in variation by selecting some types at the expense of others. The change may be small depending on the severity of the selecting factors. And I don't forget about hidden variation at all -- it seems to me it is often generally forgotten in fact by some who seem to think all variation is produced by mutations. It is hidden variation that is selected FOR in many situations of natural selection: Poison variety of newt hidden in nonpoisonous newt population gets expressed phenotypically as newt population is eaten by newt-loving snake; antibiotic-resistant bacterium hidden in nonresistant bacteria population gets expressed after nonresistant ones are killed. In both cases while there may still be some variability left in either population, the overall effect is a reduction in variability as there are simply fewer alleles (or resistant bacteria). Some alleles (or bacteria types) may no longer exist in the population at all. Some variation may certainly remain in the new selected population but my only point is that although there may be equilibrium or very small effects from any of the "processes of evolution" (except migration and mutation), the effect is always going to be in the direction of reduction of variability.None of these processes increase variability to say the least, but an increase in variability would seem to me to be THE engine to drive "macroevolution" if it is really possible. And for the processes that DO increase variability, mutation and migration, all migration does is add BACK alleles that were previously cut off or reduced in a previous population-reducing event in that Species, restoring a pre-selection condition, and that leaves mutation as the only possible mechanism for increasing variability, and mutation is still a very iffy thing in my mind.Hey if I'm wrong I'll admit it, but I haven't seen it yet. Most of the answers have been about OTHER processes acting in the opposite direction, which actually come down to one, Mutation, and I've admitted that it MAY counteract the reductive effect depending on what it really is, its rate, its life-enhancing versus life-compromising qualities etc. etc. etc. -- but that's to my mind another topic. I just keep coming back to this, that the overall TENDENCY of all the other "processes of evolution" is reduction of variability, reduction of allelic alternatives, even to the complete elimination of allelic alternatives at the extremes of these same processes. The point is that the direction is never toward increase, except possibly through mutation, and I don't yet know what to believe about mutation. ALL of these processes, while called processes of evolution, all work in the very direction that makes evolution past a certain point impossible. UNLESS mutation can save the day.

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No, because this ["processes of evolution"] is an independent process [from mutation] that is always true whether mutation occurs at a rate that can overcome it or not.

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Mutation is a "process of evolution"; it is not independent from it. It is independent of selection, but not independent of evolution.

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Yes I know it is a "process of evolution" and my point WAS that it is independent of natural selection and all the other processes that select.

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ALWAYS selection decreases diversity.

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Do you have any sort of reference or source to support this absolute statement?

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I think it's obvious, but I have run across statements that led me to this conclusion so I'll see if I can dig some up.

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I haven't yet seen anything that contradicts it.

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Off the top of my head - hemaglobin allelic diversity is maintained by selective forces. If an individual is homozygous wild-type, they are susceptible to malaria (the selective force); if they are homozygous for the sickle-cell allele, they have anemia. Thus the allelic diversity of having two hemaglobin alleles is maintained in the population, because heterozygous individuals are positively selected for.

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There it is - an example of selection maintaining diversity.

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Well, that's very interesting, and something to think about, but 1) it's not exactly typical of the processes of evolution, and 2) maintaining diversity doesn't contradict my contention. Equilibrium, very slow changes, none of that contradicts it. Only INCREASE in variability would contradict it.

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You can take the "ALWAYS" off the front of your statements.

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Not yet.

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The only question is whether mutation increases genetic diversity enough to keep the theory of evolution afloat.

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Why do you think selection acts faster than mutation? You are so adamant about it, but you haven't provided any evidence for why you think the rate of the former is higher than the rate of the latter.

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I'm simply struck by the fact that except for mutation, the processes of evolution all select in a sense even if they don't select for the best adapted, in other words all tend to the reduction of variability. Migration tends only to restore previous variability, adding nothing new, and mutation is the only process that contradicts the tendency to decreased variability. I don't think this fact is even noticed generally. I haven't got to the point of being able to think about rates. That's next I suppose, but I'm still working on getting this on the table.

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Yes, your bacterium. But still in my mind are the examples from the PBS program that called the process of selection of the poisonous newt and the antibiotic-resistant tuberculosis "mutation" while nevertheless ILLUSTRATING the process by diagrams showing that the adaptive trait was present in the beginning of the process. Surely that is not mutation, that is simply an already-present allelic variant. And such a case makes the whole question of mutation very iffy.

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How do you think that that adaptive trait came about in the first place?

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I tend to think all such traits are what somebody here called "hidden" traits if I understood his use of the term, that is, they are latent in the population until a selective event kills off or reduces the alleles with greater frequencies and allows it to come to the fore.

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This, I think, is a fundemental problem that you are falling under. Mutation had to have happened at one time or another.

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There's the assumption I keep finding in most of you here, this notion that mutation is the ONLY way new traits are created. But the most common way is for alleles with lower frequencies and probably recessive character to be expressed in the phenotype as those with higher frequencies are suppressed by the selecting factor.

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This mutation may already have been present in the population but not expressed, until some selective pressure made it beneficial to HAVE that mutation. How do you think you get variations in allele's??

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As above. You describe the same process but assume that the origin of the allele was mutation. I don't assume that any allele is produced by mutation, but is "already present in the population" as a normal variant, given in the Species at its origin. Perhaps this is because I am a creationist and you an evolutionist, so we have different expectations, different models, but you can't trump mine by simply assuming mutation because it fits your model. That begs the very question we are discussing, or at least an important aspect of it.This message has been edited by Faith, 02-16-2005 23:36 AM

I think it's noticed by everyone; you're the only one that seems to find it significant. It's like you're saying "except for everything that is up, everything is down."I mean if you specifically ignore the process that increases genotypic variation, then there's no surprise to find you're only looking at the processes that decrease variation. What about that is significant?Selection isn't evolution; mutation isn't evolution. Mutation and selection, together, are evolution. This has been repeated but it never seems to sink in. Why is that?

We've already addressed this. In a clonal population of haploids, there is only one allele (per gene.) There aren't any "latent" traits; it's impossible for there to be any.In a monocultural population of haploids, if there's any more than one allele per gene, then those additional alleles can only have come about through mutation. There's no way that they could have been latent in the population. It's not an assumption; it's the only possible explanation. There are no other possibilites in a monoculture of haploids; there are no latent traits or less frequent alleles short of those that arise through mutation. No, it's because you're ignoring evidence (or not understanding it), and we're not. We don't assume it; we conclude it, because it's the only possible explanation for alternate alleles in a monoculture of haploid individuals.

Hello Faith,I know you have a lot to reply to but I would appreciate at least a passing response to either of my replies to you.Message 40 (Message 40) in particular seems that it was overlooked. If a trait that was "hidden", or in other words recessive, then it should never appear in a population created from a monoculture. If mutations don't happen then there is never a case when the "hidden" gene could "unhide". It cannot just spontaniously show itself. It must be combined with another one of its type to be expressed. If you are only making copies of yourself with no change then this cannot happen. Lower frequencies do not automatically make a gene recessive. A particular gene is recessive simply by its properties. A new mutation might introduce a gene that is dominant and therefore expressed right away. If this expression allows the creature to be more successful at reproducing then the scenario in which you describe is overcome. Mutations are not assumed. Please address my post 40 (Message 40). Mutations are an observable thing. No creature is an exact copy of its parent or half an exact copy of its parents. This is proveable.Thank you for your reply,

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By the way, for a fun second-term drinking game, chug a beer every time you hear the phrase, "...contentious but futile protest vote by democrats." By the time Jeb Bush is elected president you will be so wasted you wont even notice the war in Syria.
-- Jon Stewart, The Daily Show

Good point about the bacteria being haploid. That greatly simplifies the situation. Absolutly any change must be a result of mutation. There is no place for recessive genes to hide.

I'm beginning to think you are not arguing in good faith, since you quote-mined yourself. The first sentence you left out: So - maintaining diversity DOES contradict your repeated claim that "ALWAYS selection decreases diversity". Selection CANNOT increase variability, only mutation can increase variability (though selection could select for a genotype that was prone to mutation). But selection CAN maintain diversity once it is introduced into a population via mutation.Also, the hemaglobin example absolutely is typical of the processes of evolution. Nothing is going on with selection on hemaglobin gene mutations that is "atypical" of evolutionary processes.To respond to another point you make: How do you think the hidden variation arose? You talk about hidden variation as if it is separate of mutations, when hidden variation is the result of mutations.At a basic level, evolution proceeds by mutation and selection. Mutation increases allelic diversity, and selection maintains or decreases allelic diversity.Compare this to your own argument above: To paraphrase, "except for mutation (which increases allelic diversity), selection (the remaining "process of evolution") decreases allelic diversity.Perhaps you'll understand why I say that from my point of view all you are doing is describing scientifically accepted aspects of the theory of evolution, but with disbelief.

I haven't got to the point of being able to think about rates.

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That is very frustrating to read. Your entire argument is rates.Perhaps you should take Ned's advice and learn a lot more about the field before claiming to have its refutation.

We don't assume mutation, as Crash and Jazzns also state, we have direct evidence. Crash reiterated his haploid bacterial monoculture; I'll reiterate my inbred mouse coat color gene example.- The black mice were inbred, homozygous at all loci, with zero allelic diversity.- White mice appeared in one generation of the population.- The genetic difference that caused the whiteness was pinpointed in the genome (a single base change causing an recessive allele).- The black parents and black grandparents of the white mice were tested for this genetic difference.- The black parents were heterozygous for the white form of the gene.- The black grandparents did not carry the white form of the gene at all.If not mutation, then where did the white form of the gene come from?It could NOT have been preexisting variants, because if that was the case, the grandparent would have to at least be carriers for the white form of the gene, which they were not. This is not "assumption", this is fact.Do you believe that mutations ever occur?

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Faith, isn't this a very odd way to come at this?
You've jumped into the kind of details that researchers like to deal with: thinks that might be called "computational evolution". (I'm makin g that up.).

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You could be right that I'm coming at this in an odd way, but I got convinced of it a while back and wanted to try it out. I don't see that I've bitten off that much. The computational part comes in because of the insistence of others that mutation cancels out my claims, which leads to demands that I give estimates of rate of mutation versus rate of selection, but my basic interest is in what seems to me to be obvious, that all the forms of selection tend to a reduction in variability. If mutation cancels it out then that's the end of that, and the computations will sort that out, but the fact that they DO all lead to reduction in variability (if they change anything at all past equilibrium) is what I'm interested in getting acknowledged. So far nothing has contradicted it. Somebody said it's obvious, and that's an acknowledgment at least, but everybody else seems interested only in disputing it.

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You've jumped in while admitting you know pretty much nothing about the topic at all. Why would you do that? Why not build a base of understanding before you dive into the deep end? There is no pedagological approach that I'm aware of that suggests that yours is a good way to go at it.

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All no doubt true, but this angle interests me at the moment and I didn't see any discussion here that it would fit into.

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There may be many other things that you need to clarify first. You haven't as yet made it clear what else you understand or accept.

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Figured that would develop as conversation proceeds.

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For one thing, separate from the theory of how evolution occured, there is the fact that evolution has occured. If you wonder if the current theory can explain how you need to come up with another one explaining that it has.

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Well, I'm the kind of creationist that denies that evolution has occurred in any sense other than the immense variations we see in Species, meaning can't occur beyond Species to anything that is not that Species, which I hardly consider proved. This view I would have expected to be clear from my first post where I talk about creationists needing to establish an end point to the processes of evolution to show that they can't proceed beyond Species. I did think I might eventually get into discussions that bring out the general viewpoints but I didn't see one going on at the moment and this topic interests me, what can I say?But if you say so flatly that evolution HAS occurred, why carry on the charade of discussing it with creationists, as obviously you aren't going to be open to any creationist argument?

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If, on the other hand, you think that it hasn't happened at all. You need to forget about the theory and get back to the underlying evidence that shows that it has occured (by whatever mechanisms). At the extreme this means backing up and recognizing what has been called "deep time". The evolution of life on earth has occured over a period greater than 3 billion years. You willingness to accept that evolution could happen is bound to be affected by your acceptance of the time scales. If you don't accept them then why would you worry about mutation rates?

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I'm not worried about them. My topic is the processes of selection and I haven't gotten around to thinking about how mutation affects them, simply acknowledged in response to others here that perhaps it does. I do consider the billions of years to be unproven, and I've read enough to know the basic outlines of the argument.

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Or even if evolution occured. All you have to do is show that the 3 billion years value is wrong.

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That's one way, but it's not the only way. There are many angles on this topic. I'd hope that a creationist who has the scientific knowledge might come along and talk to me about what I'm trying to say here.

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How about one step at a time.

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If you wish to stick to this then you need to show the math that shows that various selective pressures will reduce variation under specific mutation rates.

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This kind of work is done by evolutionary theorists (though I don't know enough to be able to point to the publications). If you want to suggest that your ideas are right then you have to start with numbers. Produce models showing what happens with various rates of mutation and selection.

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Actually, if it is clear that all the processes of evolution except mutation tend in the direction of decreasing variability then I've made my point and the mutation question can be considered later. That's all I was after here. If it's accepted then end of subject. Its dominance over mutation hasn't been proved but that's another subject. I'd be happy just to get my simple observation of reduction in variation through all these processes acknowledged.

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It seems you haven't the tiniest bit of reason to support what you are suggesting. The only reason you are bringing it up is because you don't like the idea of evolution itself.

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I'm bringing it up because it struck me that if all the processes of evolution tend to a reduction in variability that that's a very good clue to where the end point of evolution that creationists need to establish may be found. I wouldn't expect to be able to work all this out with all the scientific details. It just seems to me to be a completely new angle on the problem and full of potential, and actually I thought that creationists would be more interested in thinking about it than evolutionists, but there don't seem to be many creationists hanging out here, or at least they aren't showing the interest I expected. I figured out from this discussion that the only interference with the tendencies to genetic reduction is mutation, so I consider it to be a very fruitful discussion. If the computations you are talking about are the next step then I'm probably not likely to take it. If there's anything to what I'm suggesting somebody else will have to.

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How about being a bit honest and admit that you are not either going to believe what you are told or do the enormous amount of work necessary to understand the science at the level of detail you are attempting to discuss.

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The second statement about the enormous work I conceded above.Another discussion I could get into is the Biblical Flood answer to the Geologic Time Table as the only likely alternative explanation for the geological facts of the strata and fossils. But it was this topic that interested me as I said, and still seems to me to have a lot of potential.

Faith, since the above seems to be your mantra:
Specifically, what do you consider the "processes of evolution"?

I'm sorry I even hinted at you discussing in bad faith. (and excuse the hint of a pun as well ). I think it has been clear from the beginning (but maybe no one was absolutley unequivocal) that we agree that selection is a reduction in variability much of the time (not all the time but much of it).Yes, selection (particulary to fixation in a population) is a reduction of variation in a gene.Clearly, you have also been shown that mutations aupply variation. Only calculations can settle the question as to when they supply enough and when they don't. One can obviously construct scenarios where the rate of mutation can be overcome. The idea of the flood and ark is one of them. The fact that there isn't a consistent bottleneck for all the animals that were supposed to be on the ark is just one of the more minor falisfications of that idea. Ok, as long as you're willing to understand it is a bit more messy than some areas of discussion; why shouldn't you discuss what you want? It also needed a separate thread since it is one of the rare topics that hasn't been discussed to death. Well one reason is that a good discussion is fun. You should note that when you say that the limit is at the species barrier (which is not where many creationists now but "kind" -- while they work very hard to avoid defining it ) that has been discussed in many threads around here. The occurance of speciation has been documented a rather large number of times. We all hope that a creationist with some scientific knowledge will come along. That is when it is most fun. However, they don't seem to appear and if they do it is with very, very little knowledge. Then they avoid the simple, most obvious issues like the age of the earth one. Personally I keep trying to point YEC'ers at it but they shy away or give up very early.If you hang around for a few months you might begin to suspect that there are not any creationists with the requisite knowledge. You might find that, search as you might, you won't find the creationist sites making arguments that we haven't had fun with several times over here. You might even begin to wonder what all of that is telling you. Not being an evolutionary biologist I can't be sure, but I think you have a good point. I'm pretty sure that the issue of variability and viability of gene pools in the long term is actually examined and modeled by researchers. It is looked at just because you have, at the base, a valid point. However, it isn't the big giant killer you think it is.You should also note that in the process of science it is those same researchers who do the most rigorous digging into such issues. You seem to think that a bias will blind them but that is why we don't relay on the thinking of just few individuals. Oh good! This is one that has been discussed at some length. However, we have had no good explanation that stands up to scrutiny.

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I don't think this fact is even noticed generally.

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I think it's noticed by everyone; you're the only one that seems to find it significant. It's like you're saying "except for everything that is up, everything is down."

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Great. Then the discussion is at an end.

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I mean if you specifically ignore the process that increases genotypic variation, then there's no surprise to find you're only looking at the processes that decrease variation. What about that is significant?

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Selection isn't evolution; mutation isn't evolution. Mutation and selection, together, are evolution. This has been repeated but it never seems to sink in. Why is that?

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I'm sorry, it hasn't been repeated, I've had to extrapolate it. The lists of processes of evolution present them all separately-and-equally as separate processes. They don't point out that most of them lead to reduction of diversity, I had to ferret that out. They don't point out that mutation is the only one that increases diversity, that got brought out mostly in this discussion. I'm the one who said it sounds like the definition should be changed from Evolution = change in the frequency of alleles to Evolution = Mutation PLUS the selection processes that reduce diversity. It is never put that way in discussions of evolution. Mutation is merely listed as one process of evolution.Fine. If this is now the going definition of evolution, acknowledging all these elements in the process, fine. I've learned something. If you guys already took all this for granted, you might recommend that the basics that are presented to students and the public be restated to represent what you take for granted, as at present they give another picture.I know where to go with this information next so at least the discussion has been valuable for me.