Evolution Requires Reduction in Genetic Diversity

You can get entirely new combinations from a new set of allele frequencies, not just a subset of the original. Recessives can be more frequently expressed, traits with multiple genes can have new combinations that bring out completely new traits. Some of the new traits may have shown up in the original population now and then of course, but would have been buried by the dominant traits.Inbreeding is necessary to bring the new allele combinations to phenotypic expression, which over a few generations should start to change the look of the new subpopulation compared to the original.Edited by Faith, : No reason given.

Percy is right about how I've been using the term and I can't even see how you get your use of it out of anything that has been said,.I'm talking about inbreeding within a new subpopulation that formed from another, usually much larger, population, the new population having new allele frequencies, but the individuals involved are a random mix of theformer population so there is no necessary implication of closer relationships than between any two in the earlier population. There was no reason for you to say this in the first place since nobody had said that inbreeding changes allele frequencies. There is also no other reason to say it either, that I can see. Your weird responses were driving me crazy. I'm glad I got off this thread for a while.Edited by Faith, : No reason given.

And migration as I was using the term and so on.NOBODY EVER SAID INBREEDING CHANGES ALLELE FREQUENCIES. OF COURSE no evolution occurs in these inbred lines. THIS IS EXACTLY WHAT I'VE BEEN TALKING ABOUT FOR YEARS. When you get to the point of so many fixed loci you've reached the end of any possibility of further variation, that is, the end of evolution. By stages of decreasing genetic diversity.Drift and selection (which includes my use of the term migration as a form of random selection like drift) is the evolving part, in both breeding and microevolution in the wild. Fprtunately mutation of any consequence is so rare as to be negligible or you could never maintain a breed.
/ For the lab experiment I'd like to see done you'd have to start with a population that has high genetic diversity. I wonder if it's even -possible to find one.Edited by Faith, : No reason given.Edited by Faith, : No reason given.

Why can't you just see how it works from my descriptions? I've given enough of the reasoning for that many times.

This needs more of a response. You apparently didn't notice where I said these same traits can emerge from time to time in the original larger population as well but would be buried by the dominant traits. Or overshadowed. Or suppressed. Or whatever the higher frequency alleles do to the lower frequency alleles.The traits that dominate in the population are those with the highest frequency of alleles along with other factors such as dominance of course, so if they're low frequency they'll only show up here and there once in a while, but where they are high frequency, over generations of inbreeding they should combine with other high-frequency traits that may be low frequency in the original population. So it won't just be the emergence here and there of a single trait but new combinations that start showing up, which eventually give the daughter population a new set of traits for a new "look" ifrom that of the original population. Perhaps new striping pattern plus new coloration plus new ear shape etc. Just think about the implications of new allele frequencies as I just tried to describe the effect. The alleles that are high frequency in the new population don't have to have been "impossible" in the original population, just very rare, BUT the COMBINATIONS of a number of alleles that are now high frequency but in the old population lower frequency, could have been impossible there though now favored. Repeat: Combinations of high frequency alleles that were low frequency before should definitely create new combinations of traits from those of the original population. Not if they refuse to think it through it won't. I haven't seen an attempt to make a point with hypothetical alleles that works and I haven't been able to come up with one of my own either. What?Even if a mutation contributes something to the new traits it has to be high frequency to come to prominence in the new population and that involves a very strong selection factor BEFORE the population split. One mutation isn't going to change anything. You aren't following the argument. Mutations also have to be selected and isolated and that's what brings about the decreased genetic diversity. The mutation is just another allele that has to be selected or mixed in new frequencies.Edited by Faith, : No reason given.Edited by Faith, : No reason given.Edited by Faith, : No reason given.Edited by Faith, : No reason given.Edited by Faith, : No reason given.

Although the case of a much smaller number of individuals forming the daughter population gets the point across more clearly, I do not limit the possibilities that way. Eventually any population that continues to develop new traits is doing it with decreasing genetic diversity and is going to end up in the same place. Perhaps founder effect is always a stage in what I'm describing.I found this statement on the "Founder Effect" Wikipedia page very interesting: Yes. YES! Seems to be saying that the new allele combinations ALONE are sufficient to lead to speciation, contrary to some pretty aggressive assertions on this subject in this thread.Certainly not to the "subsequent evolution of new species" of course, because that is impossible with the decreased genetic diversity that brought about the new species, as I've been arguing.Now I have to stop for a while and come back later.By the way, I will use whatever terminology gets my point across. I hate to give up "migration" because it's such a natural term for the use I put it to, and unnatural for what you mean by it but I care more that you can understand me.Edited by Faith, : No reason given.

Yes, a small chance that ONE individual will have that combination but who cares? To matter it would have to be selected. It COULD happen but the odds are very small. I'm talking about traits that come to CHARACTERIZE a population by being possessed by many individuals, and if the alleles that make up that combination are high frequency in the daughter population whereas low enough frequency in the mother population to show up only once in a while or never, the point is the new allele frequency has brought about a new subspecies. The occasional appearance in individuals in the original population of the same traits or even combination of traits is completely beside the point and I don't know why you think it matters. It's me saying the low frequency alleles don't show up in the original population due to the domination of the high frequency alleles, but how that occurs, perhaps by a combination of factors but at least by sheer numbers, the different frequency of alleles, is totally irrelevant to this discussion. 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. You are NOT following the argument. To figure in the situation I've been describing forever here THEY HAVE TO BE SELECTED. Sheesh. If they stay in the population for a long period of time then they will be getting duplicated and passed on, but until they become high frequency they are not contributing to the new subspecies. Oh my aching head.I have to go back to HBD's post first, but it may not be until tomorrow.

Yes, exactly. But HBD's use is going to make it impossible to continue to use it this way although that's how I've used it for years. And I thought I got it from websites about population genetics.

That is the ONLY way I've EVER used the word. I've NEVER used it to mean that and I don't understand why context doesn't make that clear. I'm ALWAYS talking about a daughter population becoming REPRODUCTIVELY ISOLATED from the parent population as a result of MOVING AWAY FROM IT. It's simply that noving away is a more certain way of ending gene flow than any of the partial splits from the parent population, and ending gene flow is the main point I'm trying to get established because gene flow makes things too complicated. You keep reintroducing gene flow but that's been explicitly eliminated by my wording: REPRODUCTIVE ISOLATION alone ought to get that across. By that definition I never use. But in ALL my descriptions I'm talking about a number of individuals leaving the parent population and becoming reproductively isolated from it at some distance. There they constitute their own subpopulation and their new allele frequencies get worked through that subpopulation over some number of generations of inbreeding within that population. This brings out the traits in new combinations because of the new allele frequencies and over time produces a new subspecies out of that daughter population. That's unfortunate because I NEVER use the term "migration" as an evolutionary process. I wish there was another term for that process as a matter of fact. It's a pretty simple idea: gene flow resumes between formerly isolated populations. I don't see why since in many cases the number of those individuals is specifically relevant to the level of genetic diversity in the population. Founder effect is a dramatic loss of genetic diversity, but most population splits are not that drastic by a long shot and reduction of genetic diversity is hardly noticeable. This is one reason I like ring species for an example: a series of population splits, again the numbers of individuals determining the degree of reduction of genetic diversity, each split decreasing the genetic diversity from the previous but not necessarily dramatically until the end of the series. True, which is why I try to be very clear that I'm talking about its establishing reproductive isolation in its new location and explicitly eliminating gene flow from the picture altogether, such as eliminating hybrid zones between it and the former population and so on, although in reality these are common occurrences. Gene flow doesn't stop the pattern I'm describing: there would still be overall reduced genetic diversity, but it makes it much harder to describe so that's why I like to avoid it, as in Two Steps Forward, One Step Back etc. Yes, the most certain barrier but not the only; but the way reproductive isolation is brought about is incidental so I don't make an issue of it. I would think simply stating that the new subpopulation inbreeds in reproductive isolation from all other populations gets across the condition I have in mind. BUT IF IT DOESN'T AND YOU REALLY NEED IT SPELLED OUT FOR THE SAKE OF IMPROVED COMMUNICATION I'LL TRY. Yes, but all this is incidental or circumstantial. I say migration because to my mind it seems the clearest way of picturing enough distance to make reproductive isolation most likely. Besides, chickens DO sometimes cross roads to get to the other side. BUT I CAN TRY TO GET ALL THE INCIDENTALS INTO THE PICTURE IF IT WOULD REALLY HELP COMMUNICATION. Edited by Faith, : No reason given.

The quote on Wikipedia seemed to say that speciation can occur from the normal combinations of alleles present from founder effect so you appear to be arguing with that quote.Besides, you are assuming mutations without showing that there are any mutations there. It's often said that mutations simply do not appear frequently enough to have any kind of beneficial effect so how can you assume they're occurring here?ABE: Why do they have to be fixed "mutations" anyway? The idea seems to be that fixed RARE alleles is the point, why do they have to be mutations?Edited by Faith, : No reason given.Edited by Faith, : No reason given.

No need to accuse me of avoiding your post; I simply had to stop for the night and HBD's was on my list. I still haven't got back to his, but oh well. BUT WHEN IT IS SELECTED THEN GENETIC DIVERSITY BEGINS TO DECREASE. By now this really ought to be clear. AT THAT STAGE, YES. You really are not following the argument and continuing to insist you are just gives me a headache. You aren't making any sense. Yes, mutations add diversity. So what? Any form of gene flow can add genetic diversity. So what? The point is that when you are getting a new subspecies you have a new subset of allele frequencies that bring out new combinations of traits and that's in a sense a form of selection, random selection but selection because you are getting NEW traits (a single trait like a curled ear isn't a subspecies, or if you are going to call it that we need some new definitions). Yes, at this stage it is more genetically diverse. It's never been unclear, and it still completely misses MY argument. You are absolutely totally missing my point. Once the wings are selected and becoming high frequency in the new population, THE OTHER ALLELE for some other characteristic that the wing mutation originally replaced is either no longer present at all or at least starts out low frequency and eventually dropsd out altogether if the selection is very strong. THAT'S where you get the reduced genetic diversity. This is why all the mutations you can think of adding will never prevent this eventual effect of loss of genetic diversity. Whenever a trait comes to dominate a population other traits drop out. Doesn't matter if the dominating trait is mutated wings or the ordinary result of some new combination of the original alleles. Totally disproves them. You are not persuaded simply because you cannot follow the argument. ? Sigh. You can't follow the argument but the problem is your insistence that you are following it. As with any inbreeding population people will develop new traits if some number of individuals is isolated somewhere, and eventually down some number of generations probably a completely new look that could constitute a recognizable subspecies or race. Pick a tribe, any tribe, the Inuit, Mongolians, Pygmies, Icelanders, whatever, they got their own "look" or recognizable set of traits by being reproductively isolated among themselves over many generations. Meanwhile their genetic diversity will have started out low with respect to the total human population because of course the number of individuals in such a scenario is necessarily quite limited, and over time some alleles for some traits that were low frequency at the population split may drop out altogether, making the genetic diversity lower yet. Of course. In such a case it's the new population that will vary, not the original population. I'm only always talking about loss of genetic diversity within the NEW subpopulation, and I would have thought that very very clear. If new traits are coming to characterize this new smaller subpopulation THAT's where we'll see the reduction in genetic diversity as the new traits replace the former traits, it does not matter how many mutations may have occurred (though the possibility of even one beneficial mutation is remote).As for humanity at large, it would only be relevant if the two populations were reunited. Then if the supposed new traits become high frequency in the reunitedpopulation then the traits they replace will become low frequency or drop out if selection is strong. And again, this is the reduction in genetic diversity I'm always talking about that always occurs with the development of a new look to a population or if by genetic drift a recognizable segment of a population. You don't get "evolution" except where the genetic diversity is being reduced and it doesn't matter if the new traits came by mutation or by new combinations of old alleles, though the latter is really most likely what is happening. Already discussed this above. You focus on a new trait, the phenotype, which is always more diverse wherever evolution is occurring, (the most common way what I'm saying is misunderstood); but (micro)evolution, or the development of a new POPULATION or subspecies (not just scattered new traits in individuals), REQURES loss of GENETIC diversity, so even if new mutations underlie a new set of traits, for those traits to become characteristic of a population requires the loss of the others the new ones replace.This has been explained so many times I am quite sure you'll still not get it but oh well.

If it is not selected, or high frequency in a subpopulation, then it has no part in these processes of microevolution that bring about new traits that come to characterize new populations and ultimately speciation. And if it does become high frequency and a major player in the formation of a subspecies or even speciation, then again we see the reduction in genetic diversity I keep talking about that brings evolution to an end. It always comes back to this same point. You cannot get past the fact of reduced genetic diversity. So you have a new trait, if the population can't continue to evolve that's all you have, a new trait with no possibility of further evolution.You are of course still missing the point.And mutation doesn't happen as you claim anyway. I allow it as a hypothetical because it really doesn't change my argument. But in reality mutation has nothing to do with the formation of new subspecies and you have no evidence that it does in the situations we are discussing, or even that mutations are ever viable alleles, it is purely an assumption that the ToE requires, but in reality all the phenotypic change we see is the product of recombinations of new frequencies of pre-existing alleles.Edited by Faith, : No reason given.

Fine with me. If both populations are very large THEN and only then could the allele frequency be the same. I don't know how much smaller the daughter population has to be to start seeing a difference made by different allele frequencies but possibly not a lot smaller. Of course, yes, the smaller the bigger the difference. This is obvious. As I've said, I think counting the loci for the characteristic traits should do it, but this is of course open to discussion. How on earth is discussion possible with someone as intent as you are on nitpickingly precise pedantries that miss the spirit of what I'm saying? I USE THE TERM "INBREEDING" TO COUNTER THE OTHER NITPICKING PEDANTRY THAT INSISTS THERE IS GENE FLOW WITH THE PARENT POPULATION IF I DON'T SPECIFICALLY SAY THERE ISN'T. Good grief. Sigh. Fine. I will throw out another perfectly good word because of your inability to get the context. Right, and I'll say that and you'll say then there is gene flow and I'll want to punch you in the nose and not be able to.ABE: NEVER MIND. I see that I should have anticipated this. I really thought the word had the meaning I ascribed to it but apparently you are right and that specific meaning of mating close relatives IS the meaning and I'll only confuse everybody if I use it as I have been. Interesting Percy got what I meant though. /ABE Great.But now I have to stop for a while.Edited by Faith, : No reason given.Edited by Faith, : No reason given.Edited by Faith, : No reason given.

I may or may not get back to your posts with the current activity I'm dealing with.If you want me to answer your questions, please write out ONE question so I'll know what you are talking about.

Well, I have had to take back my use of the term "inbreeding" as I see it was causing confusion. In this case I don't know how you are using the term or what it has to do with what I'd said. Decreasing genetic diversity is the result of the microevolution of new phenotypes in smaller populations or by selection, which amounts functionally to the same thing. If you mean the mating of close relatives, of course not. But again I don't see the relevance of any definition of inbreeding here. There are really two directions here: Drift and selection are functionally the same thing as recombination of alleles in a subpopulation. They all completely or partially isolate new frequencies of alleles into their own breeding population where the new traits based on the new allele frequencies emerge over some generations, if isolation persists, to produce a new subspecies.Mutation, however, just acts as another allele in the pool. If it's high frequency or strongly selected it will contribute its trait to the phenotype, but other alleles for that same trait will be low frequency or drop out completely and that's the reduction of genetic diversity that ALWAYS occurs when a new subspecies is developed. \But it doesn't change the fact of reduced genetic diversity when new traits are coming to characterize a daughter population, it merely makes the route to the end result more circuitous and hard to follow, so changes nothing essential. It's dispensable. The mutations in those instances almost act like they were produced on demand rather than randomly. Mutations don't just happen to show up to save the day, in fact a helpful mutation may never show up, so those examples can't possibly be taken seriously in this discussion. BUT EVEN IF THEY WERE, mutations all share the same fate I keep describing of either becoming part of a subspecies which inevitably reaches a dead end beyond which no further (micro)evolution can occur, or not being selected and being irrelevant in this process anyway. Genetic innovation can't stop the processes of microevolution that lead through degrees of reduced genetic diversity to ultimate inability to further evolve. There is no evidence that they can contribute a useful allele at all ever except those odd examples you mention, but even if they did they would only supply a variation on a trait that would end up in a new "species" that has no ability to evolve further, or not even be selected at all. See above.And again, If you want me to answer your questions, please write out ONE question so I'll know what you are talking about. Edited by Faith, : Add last sentence.Edited by Faith, : No reason given.Edited by Faith, : No reason given.