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Author | Topic: What is the mechanism that prevents microevolution to become macroevolution? | |||||||||||||||||||||||
Faith  Suspended Member (Idle past 1466 days) Posts: 35298 From: Nevada, USA Joined: |
The fact that all the people with the allele had a relatively recent common ancestor suggests that it was that ancestor who first had that allele - i.e. that it IS a mutation. Hardly. The most likely explanation is that that ancestor got it from his/her ancestors.
Once a mutation occurs it IS passed on as any other allele is, so I can't see why you would think that significant. 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.
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PaulK Member Posts: 17825 Joined: Member Rating: 2.2 |
quote: How so ? The further you go back the more likely that the ancestor who first had the allele also would have other descendants with the gene - but none are known.
quote: As of course it would be. That is hardly evidence that it is not a mutation. Whereas the fact that it is known only in a few closel related people gives us good reason to think that it is a mutation that occurred in the relatively recent past.
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NosyNed Member Posts: 9003 From: Canada Joined: |
This is not a very reasonable explanation when it is in descendents of this one person but I'm not sure how to do the math to be sure of that.
I'd like to see exactly what the difference in the gene is too. If we could see that we could know that it is a difference that can arise through mutation (though I'm not away of any difference that can not). I'd also like to see more samplings of other populations. Though it could have arisen independently we'd see the same pattern of individuals with it descended from one person. This is EXACTLY the pattern you'd expect from a reasonably new mutation. It doesn't fit into your ideas at all.
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Faith  Suspended Member (Idle past 1466 days) Posts: 35298 From: Nevada, USA Joined: |
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
Thus, the real take-home lesson of domestic dogs is that artificial selection by selective breeding can be extremely powerful, much more so than natural selection, even though the two processes operate on the same underlying gene pool. 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.
In conclusion, we can indeed say that the wolf gene pool was “frontloaded” with the dogs genome but this is not contrary to the theory of evolution. It just shows how much diversity can be brought about by artificial selection. This is a special case of evolution because it is driven by selective breeding instead of natural selection. 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.
As to why the wolf gene pool contained this information, the answer is just chance: random variation exists in any genome as a result of the mutation process. Pure assumption, no evidence.
Without variation evolution cannot operate. But with variation the evolutionary process can bring about impressive changes. It can even turn a wolf into a Chihuahua. 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.
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Faith  Suspended Member (Idle past 1466 days) Posts: 35298 From: Nevada, USA Joined: |
This is not a very reasonable explanation when it is in descendents of this one person but I'm not sure how to do the math to be sure of that. I see nothing in it that contradicts normal genetic transmission of pre-existing alleles; this one just appears to be very low frequency.
I'd like to see exactly what the difference in the gene is too. Difference from what?
If we could see that we could know that it is a difference that can arise through mutation (though I'm not away of any difference that can not). 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.
I'd also like to see more samplings of other populations. Though it could have arisen independently we'd see the same pattern of individuals with it descended from one person. 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.
This is EXACTLY the pattern you'd expect from a reasonably new mutation. It doesn't fit into your ideas at all. 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.
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PaulK Member Posts: 17825 Joined: Member Rating: 2.2 |
quote: We don't HAVE to absolutely rule it out. It is enough to note that the evidence is best explained by this allele being the result of a recent mutation. Why should we accept your personal belief that it isn't, instead of following where the evidence points ?
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Faith  Suspended Member (Idle past 1466 days) Posts: 35298 From: Nevada, USA Joined: |
Hardly. The most likely explanation is that that ancestor got it from his/her ancestors. How so ? The further you go back the more likely that the ancestor who first had the allele also would have other descendants with the gene - but none are known. 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.
Just that if it's a mutation, it isn't a mutation that occurred in any living individual, it has been passed down. As of course it would be. That is hardly evidence that it is not a mutation. 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.
Whereas the fact that it is known only in a few closel related people gives us good reason to think that it is a mutation that occurred in the relatively recent past. 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.
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Faith  Suspended Member (Idle past 1466 days) Posts: 35298 From: Nevada, USA Joined: |
We don't HAVE to absolutely rule it out. It is enough to note that the evidence is best explained by this allele being the result of a recent mutation. Why should we accept your personal belief that it isn't, instead of following where the evidence points ? 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.
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PaulK Member Posts: 17825 Joined: Member Rating: 2.2 |
quote: The fact that the allele is found in a relatively few individuals all with a recent common ancestor is "EVIDENCE" that points to this allele being produced by mutation. You claim that is is "more likely" that this is a rare allele which somehow managed to spread perfectly well in this one location by chance or for some unstated reason. But I see no argument for such a claim - which seems to be based instead on the "needs/assumptions" of your own position. Without looking at further evidence it seems that you don't have a good case - your argument appears to be circular. You assume that mutations make no significant contribution to genetic diversity and then rtry to rule out evidence against this assumption by begging the question - how else could you come to the conclusion that it is "more likely" that this is an old allele rather than a recent mutation ? If we did look at the allele itself we could come up with more evidence. If this allele could plausibly be formed by a single mutation of alleles found in other individuals in the area it is very likely that it is a mutation. The further form this case we get the more likely that it is a rare allele that survived. In fact it seems that the difference in the protein produced is a single amino acidPage Not Found | OSTI.GOV
In the mutated form, dubbed apoA-I Milano because of its origin, one of the protein's amino acids is replaced with an amino acid cysteine that has a sulfhydryl group.
A single change to one base in the DNA can produce this effect - a very small change. This is not a substitute for a full genetic analysis but it certainly indicates that this allele is well within the range available to mutation.
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crashfrog Member (Idle past 1488 days) Posts: 19762 From: Silver Spring, MD Joined: |
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. Mutations are passed on like any allele, because mutations form new alleles.
How do you know the ancestor didn't inherit it in the usual way? Because only his direct decendants have it (and not all of them). His indirect decendants - those people who are decended from his parents or grandparents but aren't decended from him - don't. Thus, we have ample reason to conclude he's the origin of the allele (pedantically, I guess, the origin would be a mutation in the germline cell of one of his parents, either the sperm or the egg from which he was born.) It's basic inheritance. He's the top of the pyramid, thus, it began with him.
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crashfrog Member (Idle past 1488 days) Posts: 19762 From: Silver Spring, MD Joined: |
Apparently the explanation is that it is simply extremely low frequency in the population, not unexpressed or hidden, just present in very few. It's present in even less than very few - 33 individuals. That's it. The trait is pretty prominent, as I said, particularly in a society where heart disease is a leading cause of death. It would be all but impossible to conceal this gene for any extended length of time, especially once we started looking for it. That seems to be a point that you've chosen to ignore; why is that? Also - could you explain how you find the evidence for mutations in the bacteria experiments I've mentioned lacking? You've dismissed that evidence without actually giving a reason why.
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crashfrog Member (Idle past 1488 days) Posts: 19762 From: Silver Spring, MD Joined: |
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? By tracing the ancestry of every human being who has it. That's 33 people. When you trace their ancestry, it all comes back to one guy in the 18th century. If it had been in everyone, at one point, then we would find that the most recent common ancestor of everyone who had the gene would be a lot further back. People who weren't so closely related to each other would have it. But they don't. The only people it's found in are these 33 people who are all closely related through one guy in the 18th century. Hence, it's a mutation that arose with him, not a mutation that arose with anybody before him or was "created in the beginning" (same thing.)
It becomes extremely rare. Not this rare. Not 33/6000000000 people. And why would an allele that provides near-immunity to arteriosclerosis due to dietary cholesterol be selected against? You don't just get to assert "selection" without explaining the selective influence. This is a beneficial mutation in Western civilization. Under what circumstances do you believe it would be selected against?
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Faith  Suspended Member (Idle past 1466 days) Posts: 35298 From: Nevada, USA Joined: |
It isn't EVIDENCE that points there, it is merely the needs/assumptions of the ToE that point there. The fact that the allele is found in a relatively few individuals all with a recent common ancestor is "EVIDENCE" that points to this allele being produced by mutation. 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.
You claim that is is "more likely" that this is a rare allele which somehow managed to spread perfectly well in this one location by chance or for some unstated reason. But I see no argument for such a claim - which seems to be based instead on the "needs/assumptions" of your own position. 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.
Without looking at further evidence it seems that you don't have a good case - your argument appears to be circular. You assume that mutations make no significant contribution to genetic diversity and then rtry to rule out evidence against this assumption by begging the question - how else could you come to the conclusion that it is "more likely" that this is an old allele rather than a recent mutation ? 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.
If we did look at the allele itself we could come up with more evidence. If this allele could plausibly be formed by a single mutation of alleles found in other individuals in the area it is very likely that it is a mutation. The further form this case we get the more likely that it is a rare allele that survived. In fact it seems that the difference in the protein produced is a single amino acid Page Not Found | OSTI.GOV 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.
In the mutated form, dubbed apoA-I Milano because of its origin, one of the protein's amino acids is replaced with an amino acid cysteine that has a sulfhydryl group. 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.
A single change to one base in the DNA can produce this effect - a very small change. This is not a substitute for a full genetic analysis but it certainly indicates that this allele is well within the range available to mutation. That it could be a mutation is not proof that it is.
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NosyNed Member Posts: 9003 From: Canada Joined: |
In the mutated form, dubbed apoA-I Milano because of its origin, one of the protein's amino acids is replaced with an amino acid cysteine that has a sulfhydryl group. 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. The fact that this kind of change CAN be caused by mutations is just ONE of the reasons for thinking it is. We know that mutations can produce a change of this type. You're suggesting that the mutation removed it rather than the other way around. So you're saying that billions of individuals have LOST a beneficial allele but the decendents of one person somehow kept it from previously?
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PaulK Member Posts: 17825 Joined: Member Rating: 2.2 |
quote: Apart from the fact that my way is a more likely explanation.
quote: It would be a little better than your preferred explanation, but it would still have the problem that - somehow - every instance of this allele seems to come from one single person. That's inevitable for a new mutation and unlikely for either of your scenarios. And of course your third scenario is of little help for your position.
quote: No, it doesn't work both ways. The evidence better fits a new mutation. Your argument seems to be circular because - so far as it can tell - it relies on the very assumption you are trying to defend. I'm not relying on a similar assumption.
quote: If you assume that all alleles come from an original creation the fact that this is a very minor difference must be attributed to coincidence. If it is a recent mutation then it would almost have to be within easy reach of the alleles found locally. So the idea that it is a recent mutation is a better explanation of why the difference is so small. So, again, the fact is that the best explanation is that this is a recent mutation. Arguing that it "could be" something else does not change the way that the evidence points.
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