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Author | Topic: Y.E.C. Model: Was there rapid evolution and speciation post flood? | |||||||||||||||||||||||||||||||||||||||
Taq Member Posts: 10038 Joined: Member Rating: 5.3 |
Faith writes: Tis indeed all abstract, but so is the ToE, so is the claim that mutations are the source of variation, and in that case not just abstract but pure wishful thinking. Which of these is abstract or wishful thinking? 1. Mutations happen.2. The difference in function between alleles is due a difference in DNA sequence. 3. The physical differences between species is due to DNA sequence differences in their genomes.
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Faith  Suspended Member (Idle past 1466 days) Posts: 35298 From: Nevada, USA Joined: |
Taq writes: Faith writes: Tis indeed all abstract, but so is the ToE, so is the claim that mutations are the source of variation, and in that case not just abstract but pure wishful thinking. Which of these is abstract or wishful thinking? These are not statements of the ToE.
1. Mutations happen. All the time and it is not a good thing.
2. The difference in function between alleles is due a difference in DNA sequence. Yes but misleading since evos attribute the differences to mutation which mostly creates no differences in function or undesirable differences.
3. The physical differences between species is due to DNA sequence differences in their genomes. Another misleading definition and I'm not sure it's completely true as stated anyway. That is, the crucial differences may be in particular parts of the genome; that is, in particular sequences that are responsible for particular differences rather than in a mere summation of sequence differences. Edited by Faith, : No reason given.
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bluegenes Member (Idle past 2498 days) Posts: 3119 From: U.K. Joined:
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Faith writes: Can. But only as an accident, a fluke, and so rarely as to be of no use to the organism. Besides which, again, this is far more an article of faith than it is a demonstrated reality. And meanwhile mutations are known to have produced thousands of genetic diseases, and in the best scenarios they simply don't change anything. You're making a mistake in arguing strongly against beneficial mutations and positive selection, because your Y.E.C. model requires them. On the loci where we find multiple alleles, neutral evolution (drift) will not account for what we can observe. Consider. There can only be a maximum of 4 original alleles per locus. But on some genes we easily find many in a small population sample. The rate of occurrence of new variants on any given gene, and the 300 generation timespan, mean that, although there could be many variations on a gene scattered throughout the population, all the new ones would be rare on drift alone. However, with strong positive selection on the new variants, we might be able to move your model closer to the actual observed results, that many of the new variants are common (because far more than 4 alleles are common on many of these loci). It's necessary that new variants on the extremely polymorphous MHC genes were beneficial on arrival and faced positive selection if there were only 4 alleles at these loci 300 generations ago. So, in order to get the best possible Y.E.C. model, the one that best fits the evidence, beneficial mutation and strong positive selection are necessary. Seriously.
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Faith  Suspended Member (Idle past 1466 days) Posts: 35298 From: Nevada, USA Joined: |
I'm going with two alleles per gene
More than one gene for some traits No beneficial mutations, they are all an interference Strong selection isn't needed, nor drift, though either might occur; just migration + isolation Edited by Faith, : No reason given. Edited by Faith, : No reason given.
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bluegenes Member (Idle past 2498 days) Posts: 3119 From: U.K. Joined: |
Faith writes: I'm going with two alleles per gene But that's demonstrably false. Or do you mean originally (Adam and Eve)?
Faith writes: More than one gene for some traits Certainly.
Faith writes: No beneficial mutations, they are all an interferenceStrong selection isn't needed, nor drift, just migration + isolation Then why are so many alleles in the MHC common? Edited by bluegenes, : redundancy removed
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Faith  Suspended Member (Idle past 1466 days) Posts: 35298 From: Nevada, USA Joined: |
You haven't shown that those alleles actually do anything. You think they do, but it's all an assumption from what you've said.
Edited by Faith, : No reason given.
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bluegenes Member (Idle past 2498 days) Posts: 3119 From: U.K. Joined: |
Faith writes: You haven't shown that those alleles actually do anything. You think they do, but it's all an assumption from what you've said. We'd all be dead if they didn't! But you're missing the point. They are there. The mutation rate and drift (including the effects of migration etc) will not give us the observed pattern. Perhaps you mean to suggest that the variants don't have different functions? Did you look at the paper I linked to earlier?
Message 26bluegenes writes: To further illustrate what I was saying about extreme polymorphism in the immune system:
The major histocompatibility complex (MHC) and its functions. NCBI quote: It is important that the alleles have slightly different products because it helps give variety to our immune system. This same variety can be observed in other species of mammal. They do not appear to have been through a tight bottleneck in the last few thousand years. I coloured the sentence and bolded the last part because the fact that each allele is present at a high frequency in the population should mean something to anyone attempting to build a YEC model. The model needs to be compatible with this diversity. You have to argue for positive selection, otherwise only the original Adam and Eve alleles would be common (only 4 common alleles, or 2 if you like).
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Faith  Suspended Member (Idle past 1466 days) Posts: 35298 From: Nevada, USA Joined: |
I did read that but since it is hard for me to read anything of any length I may have missed something. the question I have is whether there is really any difference among the alleles since "neutral" mutations don't change the function. So when function is described -- the codominant function of two alleles -- isn't it possible most or all of the alleles do the same thing?
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Faith  Suspended Member (Idle past 1466 days) Posts: 35298 From: Nevada, USA Joined: |
You have to argue for positive selection, otherwise only the original Adam and Eve alleles would be common (only 4 common alleles, or 2 if you like). I don't think so. Just random recombination of Adam and Eve's two genes with two alleles per gene for skin color could produce in one generation all the different skin colors. There is no lack of diversity in this system. Diversity is all a matter of the many possible combinations of the two alleles per gene. But my main argument is for a random selection anyway, the random favoring of certain alleles over others in the simple migration of a part of a population to another location where it has reproductive isolation. You get new gene frequencies that way, that bring out new phenotypes, others decreasing and even eventually disappearing from the new population. The original two alleles per gene now seems to me to be completely sufficient for all the diversity of life we see, including the formation of every species including some exotic or strange ones. Edited by Faith, : No reason given.
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bluegenes Member (Idle past 2498 days) Posts: 3119 From: U.K. Joined: |
Faith writes: I did read that but since it is hard for me to read anything of any length I may have missed something. the question I have is whether there is really any difference among the alleles since "neutral" mutations don't change the function. So when function is described -- the codominant function of two alleles -- isn't it possible most or all of the alleles do the same thing? Again, you seem to be missing the point. If the changes are neutral, then new variants wouldn't be common after 300 generations, so you should want the common ones not to be neutral in order to fit a YEC model. The view expressed in the paper, that variation is useful, is better for your model than "neutral".
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bluegenes Member (Idle past 2498 days) Posts: 3119 From: U.K. Joined:
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Faith writes: I don't think so. Just random recombination of Adam and Eve's two genes with two alleles per gene for skin color could produce in one generation all the different skin colors. There is no lack of diversity in this system. Diversity is all a matter of the many possible combinations of the two alleles per gene. Again, the extreme variation at certain loci is there, whether or not 2 alleles would perform the function.
Faith writes: But my main argument is for a random selection anyway, the random favoring of certain alleles over others in the simple migration of a part of a population to another location where it has reproductive isolation. You get new gene frequencies that way, that bring out new phenotypes, others decreasing and even eventually disappearing from the new population. The original two alleles per gene now seems to me to be completely sufficient for all the diversity of life we see, including the formation of every species including some exotic or strange ones. Then how have many, many "new" alleles in the MHC become common in 300 generations? Mutation and drift certainly won't give that result. Almost all the mutants would be very rare. The only thing that might (possibly) explain this is strong selection. Apart from that we would need humans and other mammals to have been around for far longer than 300 generations.......... So, which is it? Edited by bluegenes, : missing s
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Percy Member Posts: 22480 From: New Hampshire Joined: Member Rating: 4.8 |
It is worth mentioning again that eye color is determined by at least 6 genes, and skin color by at least 10.
--Percy
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Percy Member Posts: 22480 From: New Hampshire Joined: Member Rating: 4.8 |
Faith writes: I'm going with two alleles per gene If by this you mean only two alleles per gene in the original human population, in your scenario this is demonstrably false. Both Adam and Eve could have contributed two unique alleles per gene for a total of four. Even though you believe you only need two alleles per gene, you actually have a potential maximum of four. This is better for your scenario because now people have to demonstrate at least five alleles for a gene before they can claim any arose through mutation, and then they still have to show they produced new function. --Percy Edited by Percy, : Correct misstated sentence.
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bluegenes Member (Idle past 2498 days) Posts: 3119 From: U.K. Joined: |
Percy writes: It is worth mentioning again that eye color is determined by at least 6 genes, and skin color by at least 10. And it's also worth mentioning that the human MC1R gene (one of the above) has more than 30 known alleles. Adam and Eve? Maximum 4. Also, as most board members are of European ancestry, many will have visible phenotype features that owe their existence to mutants of this gene.
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bluegenes Member (Idle past 2498 days) Posts: 3119 From: U.K. Joined: |
Percy writes: This is better for your scenario because now people have to demonstrate at least five alleles for a gene before they can claim any arose through mutation, and then they still have to show they produced new function. In the MHC, there are plenty of examples of more than five in small samples, like 100 individuals. There can be more than five at a 5% rate or more in the sample. That's impossible from Adam and Eve in 300 generations by drift alone. It requires positive selection of novelty, and it is Faith (although she doesn't realise it) who needs new function and positive selection for her model.
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