What is the mechanism that prevents microevolution to become macroevolution?

You must not be keeping up with the creationist arguments. No creationist denies genetic adaptation, natural selection or any of that.I'm not "rushing to debunk" mutation. I've been trying to get a grip on what it is and does for some time now and the better I understand it the less it looks like it could actually do anything to further evolution. I wouldn't think that the processes that bring about a change in allele frequencies in a population would be a matter of opinion. Edited by Faith, : No reason given.

Inevitable not just possible. But "adaptation" through selection pressures isn't always the point of changing allele frequencies. All kinds of things change them. Simple population splitting changes allele frequencies. Gene drift changes allele frequencies. Etc. etc. The inevitability of adaptation doesn't change. I have no problem with new alleles being introduced but this is generally assumed in the discussions here, rather than proven or demonstrated, except in a very few cases whose result is questionable to my mind. Edited by Faith, : No reason given.

Well that was good for a laugh.The moniker. Hm.I like iano better. But I'm kind of conservative. I don't like a lot of change. Rattles the nerves.{Sorry I hit the "edit" instead of the "reply" button by mistake, which can happen thanks to my Admin alterego, and put my answer where your post had been. I hope I restored it to its original condition.}Edited by Faith, : No reason given.

I've said many times that it's just one of the ways speciation comes about, but all these involve change in allele frequencies. It's change in the frequency of alleles in a population that brings about new phenotypes and ultimately speciation. Isn't that a familiar formula? It's the formula for Evolution, isn't it? Evolution = change in frequency of alleles in a population. Or is that formula now scrapped?Splitting the population is just one way to describe what the "evolutionary processes" all do. Change in frequency of alleles is brought about by isolating a part of a population, either partially or completely, geographically or through severe selection by the death of those that can't adapt to a new environment, and so on. This allows other alleles to be expressed more frequently. Even sexual selection and gene drift may be said to isolate a population in a certain sense, without actually separating physically from it but by allowing the selected features to reproduce in greater numbers and come to dominate the whole population over time at the expense of other traits.Change in allele frequency simply means changing to more of some alleles and less of others than the original population had. Roughly, whatever allele the population has more of is what determines the phenotype character for that trait in the population. That's a high-frequency allele. You get a population of blue-eyed people when there are more alleles for blue eyes in the population than other kinds. More little b's means more pairings of little b's so more blue eyes, etc.So, as these new frequencies work their way through the new population by recombination, a phenotype that is different from that of the former population comes about. What was previously less expressed is now more expressed and vice versa. This process affects some unknown number of genes and their alleles, depending on all kinds of things having to do with which individuals ended up where. This may not even be knowable for a given population because you'd have to study every member of the population and track its history to be certain about the numbers and frequencies involved.Now, just considering this process alone, putting aside mutation for the moment, you will NEVER have new alleles because all you have is what was already present in the original population. You'll have only more or less of different alleles of the same collection of alleles, and MAYBE you'll actually have NO alleles of a particular kind because it's possible for those to be left out of the shuffle. They'll still be in the broader population but in the one they aren't in, that trait will not be expressed; other alleles are going to get expressed instead.The actual effect of there being none of a particular allele may not be any more striking than an allele's existing in the population at a very low frequency, but the point is that a change in frequencies CAN involve a loss of alleles and NEVER involves the addition of new alleles. All you have to work with is what was already in the original population; again, assuming no mutation.Over time, with many population splits, with natural selection, with geographic isolation, with founder effect and bottleneck, all these "processes of evolution" working on populations, the overall trend is going to be toward a loss of alleles in an isolated population. Those may still be present in the other populations of the same species, and if gene flow or hybridization occurs between them then lost alleles may be reintroduced, but if the population is isolated and there is no gene flow between it and the other populations, it may develop in the direction of speciation. I'm just accepting the evolutionist's terms. If they want to define speciation by inability to interbreed it doesn't matter, to me that's just the extreme of this overall tendency we're discussing, that moves in that direction whether it arrives there or not. In other words, it isn't speciation as such but the development of new genotypes/phenotypes I'm focused on, that may or may not become a new species. That's a logical question and I don't know. One answer MJFloresta gave is that they may be able to interbreed but simply don't for whatever reason. Speciation would be the extreme of the processes involved, by which time the frequencies of alleles are very different between the populations. Theoretically they should be able to recombine just because they all have the same basic genetic structure, same genes etc., so there must be something about the lack of fit that prevents it.Thinking about mutation in this respect, however, why should that prevent interbreeding either? Mutation simply changes an allele, but if the basic gene is there in both populations why wouldn't the new allele simply combine with whatever other alleles exist in either population? In other words I don't see how a mutation would be any more of a barrier to interbreeding than it would be to sexual recombination within the population it occurred in. Whether the alleles in question were always there, or introduced by mutation, they have to be able to pair with others if they are going to be passed on, and I see no reason why they should have any more trouble interbreeding than inbreeding, or any more trouble doing either than a pre-existing allele would.In other words, if alleles for the same gene can be "incompatible" at all, then what is the nature of this incompatibility and why couldn't it occur among pre-existing alleles as likely as among mutated alleles?MJFloresta suggested on another thread that it's not that they CAN'T interbreed but that they don't, and that it should be possible to test this by artificial means. I thought that made sense. Kuresu then put up a list of known hybrids for many species which looked to me like a way to define a Kind, but at least it showed that it's possible to interbreed species you might not expect. Right. I lose track of what I'm trying to say sometimes. Rare alleles WOULD be more likely to be lost, that is, lost to a new smaller population that migrated from the original. Very unlikely to take the rare alleles with it. But those alleles have to end up in one or the other population and if the population split reduces the number of individuals appreciably the rare alleles will have a better chance of being expressed, in whichever population contains them. Simple reduction in the number of competing alleles, caused by the population split, is the change that would allow it. You'll get more of whatever-it-is in the population over time simply by reducing the frequencies of all the other alleles for the same gene -- unless there's some selection process working against it of course. It's the same model scientists use, change in allele frequencies through various population-changing processes. I'm merely analyzing what's really going on in it. I haven't added anything to the processes I've seen described in many discussions of how population genetics works. The difference seems to be that evolutionists assume mutation behind the whole thing, and so fail to notice what I'm pointing out about how it works in the direction of reducing genetic diversity -- again, without mutation in the mix. If you would just keep mutation out of the picture for the time being and just think through the processes I'm describing, which are all standard science that evolutionists refer to all the time, you ought to be able to follow it all to the logical conclusion I keep pointing out here, which is that genetic depletion IS the overall trend in all these processes. There's nothing of opinion in this at all, it logically follows from an understanding of what these processes actually do. If you want it to float evolution in the face of all the genetic-variability-reducing processes, there is. Well, if you would just follow the argument here, you'll have to see that what presently is credited to mutation is nowhere near supplying the number of useful changes needed, that is, the number needed to rival those changes that take place in every sexual recombination, or for that matter in whole populations as allele frequencies change over time -- billions of changes, all of which tend in the direction of decreasing genetic variability. I haven't said anything that contradicts anything in standard population genetics. They just don't recognize the implications of it that I'm trying to bring out.Edited by Faith, : No reason given.Edited by Faith, : No reason given.

No, because you simply refuse to follow the logic of the discussion which is where the evidence is. The evidence is in the facts I've mustered from population genetics presentations. Just think it all through as I've indicated.

I would expect an allele to be the length of the gene. But perhaps I'm wrong about that.

This idea that empirical evidence is required here is just wrong. If you really followed the argument I would think that should be clear. When one is bringing out the implications of a known set of facts, the proof is in the reasoning, not in new evidence.If anybody needs to supply evidence, it's the evolutionists who merely assume without evidence, as crashfrog did in a recent post, that mutation explains the development of new phenotypes.I'm sure experiments could be constructed to test some facets of what I'm saying, however, but I'm not in a position to do it.

So, OK, it's dominant, it can't be hidden etc. But the fact that all these people have it apparently from a common ancestor certainly suggests it's passed on just as any allele is, so I don't see any reason to believe it's a mutation. How do you know the ancestor didn't inherit it in the usual way?Edited by Faith, : No reason given.

Apparently the explanation is that it is simply extremely low frequency in the population, not unexpressed or hidden, just present in very few. The actual facts don't suggest that it was inherited in any way other than the normal, and I see no reason to assume that it originated in a mutation from anything you've said. Perhaps I'm missing the essential point you're making? I dunno. It all looks like what I've been describing. Edited by Faith, : No reason given.

Hardly. The most likely explanation is that that ancestor got it from his/her ancestors. Just that if it's a mutation, it isn't a mutation that occurred in any living individual, it has been passed down. I had the impression before that this was supposedly a brand new mutation. But if it was inherited from an identifiable ancestor, then the question comes up how you know it was a mutation then either, rather than inherited just as it is in the present possessors of it.Edited by Faith, : No reason given.

Ran across this fascinating discussion about how so many dog breeds could have descended from the one wolf kind:404: Content Not Found | The Tech Interactive Same underlying gene pool, yes, the gene pool that has been there from the original wolf. NO reason has yet been given to explain it any other way. The bolded section is a GREAT example of the common mistake of thinking that selection *brings about* diversity, exactly what I've argued on this thread is the exact opposite of what selection processes do. Selection can't increase diversity, it chooses some alleles at the expense of others, which may in fact be completely eliminated from the population under a severe selection pressure. And again, selection is only one of the many ways that alleles are shuffled or removed. And again, mutation is the ONLY way they could possibly be increased, and AGAIN, except for a very few iffy explanations, this is merely assumed and has NOT been proved. Pure assumption, no evidence. Oh there's no question but that a great deal of genetic variability is what accounts for all the breeds you can get, but this is affirmed by creationists. The question is how did the genetic diversity get there in the first place? Again, ALL they do is ASSUME and ASSERT that it was put there by mutations. Nope, the creationist assumption is just as good an explanation, that it was built in from the very origin of the species.Edited by Faith, : No reason given.Edited by Faith, : No reason given.

I see nothing in it that contradicts normal genetic transmission of pre-existing alleles; this one just appears to be very low frequency. Difference from what? How are you going to rule out the possibility that it's merely a built-in allele that has been in the human race back to a Beginning? Could simply have become rare for any of a variety of the usual causes that can occur in genetic transmission -- some other allele was possibly selected over it back there somewhere. Well, that would simply underscore its rarity, wouldn't it? I don't see how it would say anything about its origin. That is, there could be others who have it, and they could have it from a different ancestor, but it's still rare, and it's still transmitted by exactly the same rules of genetic inheritance. Mutation need not be postulated at any point in the chain. Oh it is EXACTLY what you'd expect from my ideas when an allele has been selected against in the past. It becomes extremely rare.

Yes, it's likely, but not absolutely certain, and it's also possible there ARE other descendants with it who have not yet been identified. It is evidence that it is not a mutation in a living individual. Crash is the one who gave the evidence for that anyway, when he said they have a common ancestor who is assumed to have had it. The point is its being a mutation is merely assumed whether in a living individual or an ancestor, NOT proved. If you had one living individual who had NO ancestors who had it, then you'd have a good case for its being a mutation, and I thought that's what he was saying at first. Turns out nope, it's just inheritance as usual. The most likely explanation is that it's a normal allele that was selected against in the past and became rare. The farther back you go, if you could, the more of it you should find.When an allele is selected IN, others are selected OUT, you know, often completely lost to posterity.Say you're right and this was a mutation at some time in the past. It is possible that it got selected in for a while and then something changed and it got selected out. How would you know which of the possible scenarios occurred, yours, this one or mine, from the actual evidence in hand?Edited by Faith, : No reason given.Edited by Faith, : No reason given.Edited by Faith, : No reason given.

It isn't EVIDENCE that points there, it is merely the needs/assumptions of the ToE that point there.Edited by Faith, : No reason given.

OK, then think about it this way. We have these particular facts, and they can be explained reasonably in a number of ways. Your way has no more validity to it than mine does. OK, that's fine. That's all there is on either side of the argument. It fits either my scenario or yours. However, I gave the third scenario that assumed mutation many generations ago that first got selected in and then selected out. That would explain the known facts just as well. That works both ways. You assume that mutation accounts for everything genetic, which is no less "circular" (although that term is always misused here to describe what is not circular but really inference from a theory). In any case, all the selecting and isolating processes of population genetics work on alleles already present in a population to bring out new phenotypes, and my scenario is every bit as reasonable as yours --I think far more reasonable, but I'll take the conservative position and say just as reasonable. The chemistry involved is interesting but I see nothing in the chemical facts that shows this is a mutation rather than merely an inherited low-frequency allele that was perhaps once selected against. The article simply CALLS it a mutation, because that's what the ToE decrees. It is taken for granted; it is an assumption; it is not questioned. But there is nothing in the article that supports the contention. I see nothing in this fact that decrees it must be a mutation. Just as likely the other allele or form of the gene that doesn't provide this protection is the mutated one, the one with the different single amino acid, since mutations more often deprive us of health protections than the other way around. That it could be a mutation is not proof that it is.