What is the mechanism that prevents microevolution to become macroevolution?

My argument is that reduction in genetic diversity is the inevitable inexorable trend of all natural processes towards speciation, and all species undergo these processes. It's a trend, not an "instant conver[sion]" to new species. I don't think a bottleneck always leads to speciation, but it may in fact, meaning it may lead to a new phenotype / genotype that can no longer interbreed with others of its kind -- if any near relations are even still around. I think that nowadays it is most likely to lead to this condition, however, because of the overall depletion of genetic diversity across pretty much all species. That's a guess, but as a principle, no, speciation isn't a necessary result of a bottleneck, merely likely. Bottleneck is merely a way to illustrate the situation of severe genetic reduction caused by population reduction. The kind of domestic breeding programs that simply aim to get the best of a type without regard to its survival prospects bring about the same condition, the kind that a quote I gave above called "breeding to exinction." What is breeding but a step on the way to speciation if not speciation itself? You select, you change genetic frequencies and if you get down to a few founders you certainly remove lots of alleles / genetic diversity from your new breed. That's how you GET the new breed. Yes, they are possible in the original species, but the traits of some alleles are not expressed much or at all, and could be said to be "latent," either because they occur in very low frequency or are recessive or affected by other genetic conditions I wouldn't know a lot about. These are the ones that breeders breed FOR after all, the unusual trait, the low frequency trait. These are the ones that pop up and surprise by their seeming newness in a drastically reduced new population that happened to contain them. All this newness does not require anything really new, at all, just the coming to expression of formerly suppressed or latent traits, because of the removal or reduction of competition from other alleles that formerly dominated in the original population. The point is just that it is very hard to get across this fact of inexorable genetic depletion through the normal processes of variation and speciation, because mutation keeps being assumed to take up the slack of this depletion. In fact it simply doesn't. Evolutionists automatically think in the direction of mutation as the driving force of evolution, by its supposedly increasing genetic diversity, producing new alleles and new traits to be selected, and it is very hard to get the focus off mutation and onto the fact that all the OTHER processes that affect genetic diversity are working to decrease genetic diversity. Mutation has to be able to occur at a prodigious rate with prodigiously useful effects to overcome this inexorable reduction, if the ToE could possibly be true, and so far what has been demonstrated of mutation just doesn't meet the challenge.

This makes no sense. You must have a completely novel definition of 'genetic change' if it is somehow dissociated from mutation. The sort of changes in allelic frequency you have been discussing are not genetic changes as that term is understood scientifically, they are changes in a populations genetics which is quite different. So if you think that all of the variation we see below the level of 'kind' is due to the reduction of allelic variation which was already present in the breeding pairs which got of the Ark then you clearly are denying the existence of small genetic changes. But there is considerably less evidence for the sort of superallelic variation you posit, than there is evidence for the ability of genetic mutation to create variation. All you are explaining is an ad hoc fantasy without a shred of evidence to support it. Why assume a vast amount of completely undemonstrable lost genetic information over a clearly demonstrable facility for genetic material and its machineries of reproduction to produce genetic variation.The sort of alleles we see in populations are completely consistent with the sort of genetic mutations we see regularly ocurring, where does the need to posit some other origin for these alleles come from other than from a religious pre-conviction, what evidence suggests we should adopt your hypothesis?TTFN,WK

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My argument is that reduction in genetic diversity is the inevitable inexorable trend of all natural processes towards speciation, and all species undergo these processes

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My point is that it can't be a loss of alleles due to splitting the population that produces speciation. So something else must be needed. Especially if you make interbreeding yoour definition of speciation. Without new alleles, all the alleles in the split populations were present in the parent population - yet it would be unusual to find much in the way of incompaitbilities in reproduction in the parent population - so why should the split populations be unable to interbreed unless new alleles that are incompatible are incorporated into one population or another ?

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Yes, they are possible in the original species, but the traits of some alleles are not expressed much or at all, and could be said to be "latent," either because they occur in very low frequency or are recessive or affected by other genetic conditions I wouldn't know a lot about.

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Rare alleles would be prime candidates to be lost. And there must be some change elsewhere to allow unexpressed features to be expressed. It doesn't seem that speciation would be very likely in your model.

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The point is just that it is very hard to get across this fact of inexorable genetic depletion through the normal processes of variation and speciation, because mutation keeps being assumed to take up the slack of this depletion. In fact it simply doesn't.

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But that has NOT been established as a fact. That is your opinion, and so far as I can tell it is based mainly on your desire for it to be true.

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Mutation has to be able to occur at a prodigious rate with prodigiously useful effects to overcome this inexorable reduction,

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You assert that, but without actual numbers it is simply an unsupported assertion. So far as I am aware there is no need for the mutation rate to be any greater than it has been measured to be.So at what rate are alleles actually being lost ? I don't want your opinion, I want a valid estimate based on real evidence. Do you have one ? If not then are you prepared to retract your assetion ?

Well, I was using the term Archer Opteryx used, and took it in a rather generic sense as he seemed to be using it, speaking simply of observable changes accruing over time, which is certainly not disputed by creationists. You seem to want to insist that the term must imply mutation, and I suppose it probably does for evolutionists, but simply descriptively there is no reason why it should. I guess I could drop the "genetic" if that helps, and simply say that we do not deny all the observed changes that evolutionists say accumulate in species, we simply explain them differently. But these changes occur both in the phenotype and the genotype and involve alleles shuffling -- and I guess I'm back at "genetic changes." Don't really see how to give up the term even if evolutionists mean something different by it than I do. Again, I have no other word for it in order to answer what was clearly meant by Archer O, since clearly he meant that we deny the accumulation of new traits toward speciation, and the fact is that we do not deny that. Well, as long as you insist that "genetic changes" = "mutation" then of course I am denying them. But those genetic changes as a matter of observed fact I do not deny, merely the explanation for them. There is nothing "super" about it. It's all normal well-known shuffling of alleles you can find described in any basic genetics course or certainly on domestic breeding sites. Surely there is a ton of evidence that the alternating of different alleles for a gene produces variation. Perhaps it is so ubiquitous and taken for granted it is simply hard to recognize. Mutations create variation but at nowhere near the rate of allelic substitutions and most of it is useless to the organism. "Undemonstrable lost genetic information?" What's undemonstrable about the effect of changing alleles? If you have a dozen alleles in a population for a particular gene, you get very different traits from each. If 6 of those alleles are left behind in a population split you'll have 6 in each new population that will come to characterize each population as they spread and sort through it over time, and both populations will eventually look appreciably different from each other and from the original population that had 12 alleles -- certainly a step toward speciation or divergence between the two. Genetic effect of the most common gardenvariety kind. No role here for mutation. Well, an allele looks like an allele I guess, and if mutations make alleles then why would they look different? I'm not selling a religious belief, I'm arguing evidence. I would say that the evidence I've given on this thread ought to make you realize that speciation does not require mutation, even if it occasionally makes a small contribution to it, and that nothing more than that has yet been evidenced. All the changes are all quite easily explained by the most ordinary common normal genetic operations. This does lead to suppositions about a beginning point in the past, but stick to the evidence itself. You don't have to follow me there. The evidence will lead you there.

What evidence? Your layman's opinion does not equate to evidence.I never cease to be amazed at your belief that you can overturn entire branches of science with your layman's insight.If you were THAT clever, you'd have hard evidence....Edited by RickJB, : No reason given.

We may speak of 'selection pressure', but there is no such thing as 'mutation pressure'. Nor is mutation inherently essential for speciation to occur. I don't know where you learned your high school biology (Alabama ?), but you need to re-take it.Remember, 'beneficial' is always a loaded term because it is context-dependent. With that in mind, see if you can wrap your brain around this (hypothetical) example.The AIDS virus has a protein capsid that recognizes a particular protein structure specific to the surface of human T-cells. A mutation occurs in a single base pair that changes one amino acid in this protein leaving its function as a membrane protein unaffected, but rendering it un-recognizable to the AIDS virus.Would that comprise a beneficial mutation? Do you even know what a plasmid is? Because they don't occur naturally in the germ cells of higher organisms. And yes, there are regions of the genome subject to higher rates of mutation (base-substitution, deletion) than other areas. These are relative, not absolute terms. 'Highly conserved' just means there is a very low rate of alteration in sequence, so mutation is a low frequency event, but not impossible. We may also observe regions of a genome that are 'hot spots' for mutation in that many alternative sequences are observed in a population, but usually these are not transcribed regions. That would be difficult given that there is no such thing.
Mutation does not constitute a 'pressure' - it is merely a heritable molecular event with a range of possible consequences in an organism ranging from negative to neutral, to positive.

'these genetic changes' being presumably the no-genetic changes in allele frequency. Why can't you just call them changes in allele frequency? This is nonsense. While there is nothing super about the normal rearrangements of existing alleles and phenotypic variations arising based on these you hypothesis neccessitates either a massive initial population for a kind, from which all subsequent organisms within that kind have derived and of which those subsequent organisms represent a gentic subset, or a small population with a highly abnormal genetic architecture, i.e. the sort of supergenomes we have previously discussed.There is no evidence to support the supergenomic theory and none, as far as I can see, to support the massive ancestral population theory. Your theoretical example seems to be just you pulling numbers out of the air.Without a clear enough definition of kind to specifically identify a given set of populations derived from an ancestral 'kind' population it is hard to guage what the original level of genetic information was. It would be equivalent to the sum of the information in all the extant alleles across all the populations descended from that ancestral 'kind' population. In the absence of any actual way of knowing what these progenitor populations are we are left with the ad hoc explanation that these 'kind' progenitor populations which were either highly heterogenous genetically or very large existed.To fit this into a scenario with a 'kind' progenitor population of only 2 you have even more problems. Take your 6 allele variant population. To descend from only a single breeding pair that pair must have had 3 alleles for the gene each. This suggests that they would have needed at least 1 extra chromosome each to stash these spare alleles on. So while I appreciate your distinction that in your view you could aggregate all the extant genetic variation in order to derive the makeup of the ancestral population that population would have had to be supergenomic with dozens of times the chromosome complement seen in modern species within that 'kind', either that or they would have had to had a completely different from of genetics. The whole point is that where your line of argument, since you haven't actually produced any evidence just argumentation, leads is to something which all the evidence contradicts. The initial allelic variation must come from somewhere, we have plenty of evidence that it could come from mutation and none at all that it comes from any sort of 'kind' progenitor population with the allelic complement of all the descendent populations pre-existent within that population and certainly no evidence that such a population could consist of 2 individuals.TTFN,WK

I hate to be a pedant, and I agree with your position in principle, however: There is such a thing as mutation pressure: it is basically when a mutation happens in one direction more probably than another direction (that is, a reversable mutation occurs but it is more likely to occur in one direction than another). I explained it a little better in this post for those reading who are interested.

Chutzpah I've got, in a way, but it's simply based on seeing how what I'm arguing is true, even if I get some of it cockeyed here and there. I'm not particularly clever, I'm arguing a pretty straightforward point, but I do pray a lot to be able to understand it and convey it. However, what I've given IS evidence. All you have to do is follow the reasoning. It's all there. Edited by Faith, : No reason given.Edited by Faith, : No reason given.

Ah, but your scientific reasoning (just like my own) counts for nothing without physical evidence!You're certainly smarter than the average bear, but IMHO your brand of faith requires you to jump through hoops that are beneath you.The kind of evidence I'm talking about is based on clear definitions (of "kinds", for example) and experiment (with regard to mutations). As far as I can tell, you have no such basis.Edited by RickJB, : No reason given.Edited by RickJB, : No reason given.

The problem is that phenotypes do not evolve, whereas genotypes do. Not within a population, because genetic drift is defined in terms of population divergence - it can’t happen within a population - only between them. It can be a factor in speciation, but it is not sufficient to account for speciation. But they aren’t. Speciation requires some form of reproductive isolation, be it spatial, temporal, behavioral or genetic. Then why can you not envisage any beneficial effect of a mutation, when the very term ”beneficial’ is so obviously context-dependent? Imagine a mutation that alters one amino acid in a critical developmental enzyme, lowering its thermal energy of activation without affecting other functions. Would you not expect this allele to be selected over its ancestral form in areas of the species’ range that were much colder, for ex. at higher altitudes? It would enable the organism to complete development at a lower temperature. Literally countless ”beneficial’ mutation scenarios are conceivable when you understand how biology works. Of course there is. There is a first time for everything. You have accepted that mutations can occur, how is it possible they would never produce anything novel when they simply comprise chance mistakes in transcription? That is a veiwpoint obviously arising from your pre-determined belief in YEC, but an interesting question, nevertheless.I would contend that no, there are not. This is because ecology and evironments continue to evolve and change, as they always have. Novel environments will select for novel alleles. There was no value to a gene for DDT resistance in mosquitos until we synthesized DDT and started spraying it everywhere. New niches will continue to evolve that provide new alleles opportunities to provide new advantages to their genotypes, just as new ecological niches will appear that represent evolutionary opportunities for species. This, to me, is the greatest conceptual failure of creationism - to provide any mechanism for change to occur a posteriori. If we accept that things are always changing in nature, a single creation event will never be sufficient to explain the ongoing diversification of life. You have all the answers to this question within your own words.
Your knowledge of population genetics is sufficient that you can easily appreciate how ”rare’ can easily become ”common’ after a few generations of selection. That mutations can *sometimes* be neutral simply allows them to hang around without affecting fitness under some sets of conditions. That they are potentially beneficial is not difficult to accept when you recognize that ”beneficial’ itself is a very context-dependent term, as I have explained above.

I had not heard the term used to imply asymmetry in forward/backward mutation rates. I was objecting to its use by Faith in the context of some sort of driving force in speciation.

I think it was Phillip rather than Faith that was using this term.TTFN,WK

Oops. Yes of course.
I had just finished my answer to Faith, hence my mistake.

I don't see how it is, or at least, I don't see how it's a "new phenotype" that arose through a reduction in allelic diversity. The "cheetah body plan", or the traits that we recognize as the definitive morphological character of cheetahs, didn't arise because of the bottleneck event; they were already there in the population. The pre-bottlenect population of ur-cheetahs would have included individuals that looked like modern cheetahs, and individuals that looked differently.The bottleneck didn't give rise to anything new, it simply removed other phenotypes, so that the current cheetah "specification" was the only one left.How is that a new phenotype? That's simply the loss of the old ones - a loss of phenotypic diversity, which is exactly what I've been telling you is the consequence of a loss of allelic diversity. No, it's not, because it was in the old population, too.Let's say that we have a population of tall people and short people, and that that's determined, as it is in pea plants, by a single gene that is dominant for tall.Now, imagine that aliens come down from space and because they hate tall people, they vaporize everybody who is tall. That leaves only the people who lack any tall alleles, who only possess the short allele. That's a loss of diversity, a loss of an allele (the tall one.)So, all humans are now a lot shorter. But how is that "new"? All those short people where there in the old population, before the alien bottleneck. So there's no "new" phenotypes - only a loss of old ones. A loss of physical diversity that stemmed from something that reduced genetic diversity.That's the only thing a loss of genetic diversity can result in - a loss of physical diversity. No, it's not. I've already referred to the direct experimental evidence that this is not the case. Alleles increase in diversity over time; that's the trend. Specific events might remove alleles, selection might do that (although for statistical reasons it's actually fairly hard to completely select out an allele, especially if it's recessive. The fewer number of individuals that possess an allele, the harder it is to select against.) But the overarching trend is always one of allelic increase, not decrease. That's been consistently borne out in observation and experiment, and mutations are known - known, Faith! Known like we know lightning is made of electricity! - to be the cause. If what you're saying is that they're "new" not because they're actually something different than has come before, but merely "new" because now they represent a greater fraction of individuals, that's pretty dumb. Imagine if you had a child that kept bugging you for a new toy.Now imagine if you took all of their toys but one, and threw them in the trash. Imagine if you tried to convince your incredulous child that their last remaining toy, that ragged stuffed bunny with the missing eye she'd had since she was 2, was now "new" because it represented a greater fraction of her toys - 100% of her toys, in fact - than it had before.Is that logic you can imagine convincing even a child? No? Then why is that the logic you seem to be bringing in here? What you're glossing over in every one of your posts is why we should consider a phenotype "new" simply because we lost a bunch of the old ones. How does that make any sense at all?