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Author | Topic: How novel features evolve #2 | |||||||||||||||||||||||||||||||||||||||
Tangle Member Posts: 9516 From: UK Joined: Member Rating: 5.1 |
Found this whilst reading around the Ames test. QI.
Life, don't talk to me about life - Marvin the Paranoid Android |
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Tangle Member Posts: 9516 From: UK Joined: Member Rating: 5.1 |
Dr A writes: As a first instance, let me direct you to the Ames Test. The initial state is known, the final state is known, and the mutation keeps the bacterium from dying of malnutrition. I'd have a couple of complaints if I was a creationist. 1) It's artificial - it starts with a deliberately faulty lab-bred bug.2) The mutation that occurs (if it occurs) simply takes it back to the bugs normal functioning (ie the way god intended) - not a new trait. 3) You haven't isolated the actual mutation and proved that it is genuinely new. I think it was there all the time and occasionally gets switched on when the bugs are starving. Life, don't talk to me about life - Marvin the Paranoid Android
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Dr Adequate Member (Idle past 314 days) Posts: 16113 Joined: |
I'd have a couple of complaints if I was a creationist. Also, you'd be wrong.
1) It's artificial - it starts with a deliberately faulty lab-bred bug. 2) The mutation that occurs (if it occurs) simply takes it back to the bugs normal functioning (ie the way god intended) - not a new trait. What of it? It fulfills the criteria, it's a beneficial mutation being fixed in the population. If you want an example of something else, you should ask for it. Lenski's experiments come to mind.
3) You haven't isolated the actual mutation and proved that it is genuinely new. I think it was there all the time ... Haven't you read the article? We do know exactly what is happening to the genome. The his operon is broken in the initial population.
and occasionally gets switched on when the bugs are starving. Would you care to explain why this is more likely to happen in the presence of mutagens?
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Tangle Member Posts: 9516 From: UK Joined: Member Rating: 5.1 |
I love Lanski's stuff - it's real, proper, rigorous, long term science. But not being a micro-biologist I've always taken it at face value, never tried to see it as a creationist would. No doubt they have severe objections.
This was the question in the OP. "I accept that natural selection does occur and that it can cause a population to change, but you need now to show me how the genome created those novel features because, until you do, I can say that the genome must have had them to start with." Does Lenski's stuff do that?Life, don't talk to me about life - Marvin the Paranoid Android
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Dr Adequate Member (Idle past 314 days) Posts: 16113 Joined: |
Yes. Lenski's experiments use a clonal line --- anything that was already in the population would have been fixed in the population from day 1.
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Tangle Member Posts: 9516 From: UK Joined: Member Rating: 5.1 |
PZ Myers has blogged on Lemski's responses to creationist criticism of his work. It's a fun read.
Lenski gives Conservapdia a lesson | ScienceBlogsLife, don't talk to me about life - Marvin the Paranoid Android
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zi ko Member (Idle past 3650 days) Posts: 578 Joined: |
...I would suggest that the cause (random or designed) of a mutation...
Why do you ignore the third (and more propable after epigenetics and the recent immence flow of knowledge about RNA) possibility, that of information from environment causing guided mutations? Edited by zi ko, : No reason given.
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New Cat's Eye Inactive Member |
Why do you ignore the third (and more propable after epigenetics and the recent immence flow of knowledge about RNA) possibility, that of information from environment causing guided mutations? The evnironment doesn't reach the genome in order to mutate it.
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Taq Member Posts: 10085 Joined: Member Rating: 5.6 |
Why do you ignore the third (and more propable after epigenetics and the recent immence flow of knowledge about RNA) possibility, that of information from environment causing guided mutations?
We ignore it because the evidence doesn't support it.
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zi ko Member (Idle past 3650 days) Posts: 578 Joined: |
The evnironment doesn't reach the genome in order to mutate it. -------------------------------------------------------------------------------You seem so sure.... Can you bring any evidenc for random mutations in metazoa?
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zi ko Member (Idle past 3650 days) Posts: 578 Joined: |
We ignore it because the evidence doesn't support it.
So what is the evidence supporting creationism or, most importanly, random mutations in metazoa?On another thread on the same question you gave me this. I quote: Abstract "I estimate per nucleotide rates of spontaneous mutations of different kinds in humans directly from the data on per locus mutation rates and on sequences of de novo nonsense nucleotide substitutions, deletions, insertions, and complex events at eight loci causing autosomal dominant diseases and 12 loci causing X-linked diseases. The results are in good agreement with indirect estimates, obtained by comparison of orthologous human and chimpanzee pseudogenes. The average direct estimate of the combined rate of all mutations is 1.8x10(-8) per nucleotide per generation, and the coefficient of variation of this rate across the 20 loci is 0.53. Single nucleotide substitutions are approximately 25 times more common than all other mutations, deletions are approximately three times more common than insertions, complex mutations are very rare, and CpG context increases substitution rates by an order of magnitude. There is only a moderate tendency for loci with high per locus mutation rates to also have higher per nucleotide substitution rates, and per nucleotide rates of deletions and insertions are statistically independent on the per locus mutation rate. Rates of different kinds of mutations are strongly correlated across loci. Mutational hot spots with per nucleotide rates above 5x10(-7) make only a minor contribution to human mutation. In the next decade, direct measurements will produce a rather precise, quantitative description of human spontaneous mutation at the DNA level." Direct estimates of human per nucleotide mutation rates at 20 loci causing Mendelian diseases - PubMed ------------------------------------------------------------------------------and my answer was:I Quote: "So this famed evidence about random mutations in metazoa ends up to an indirect estimation by a scientist, who in 2002, hopes that other scientists, during next decade (which already had ended), would rather make a direct measurement, evidently necessary for any conclusion!!!!" Have you since foumd a better evidence tha this? Edited by zi ko, : No reason given.
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New Cat's Eye Inactive Member |
The evnironment doesn't reach the genome in order to mutate it.
You seem so sure.... Can you bring any evidenc for random mutations in metazoa? DNA replication is imperfect and leads to random errors in the gemone that are referred to as mutations. Here's a paper that goes into great detail about it: http://www.nature.com/...lication-and-causes-of-mutation-409 But that's beside the point that the photype acts as a barrier between the envoronment and the genome, and thus prevents the evironment from directly mutating the genome. Granted, you could nuke your balls in the microwave, or something like that, but I don't think that's what we're talking about.
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Taq Member Posts: 10085 Joined: Member Rating: 5.6 |
and my answer was: I Quote: "So this famed evidence about random mutations in metazoa ends up to an indirect estimation by a scientist, who in 2002, hopes that other scientists, during next decade (which already had ended), would rather make a direct measurement, evidently necessary for any conclusion!!!!" Have you since foumd a better evidence tha this? That evidence still stands. The author arived at an estimate for a mutation rate by measuring the appearance of genetic diseases such as achondroplasia. These are dominant genetic diseases meaning that you only need one copy of the disease allele in order to express the disease phenotype. So when a child is born with one of these diseases while the parents do not have the disease this indicates that the change is due to a mutation. So why would cells guide the process of mutation to produce these diseases? Or are mutations random, producing a wide range of effects? I can also cite the Luria-Delbruck fluctuation experiment, the Lederberg plate replica experiment, as well as direct studies of polymerases all of which demonstrate random mutation. I have gone through these experiments with you in the past, and you still ignore them. The evidence hasn't gone away. The evidence clearly demonstrates random mutation with respect to fitness.
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zi ko Member (Idle past 3650 days) Posts: 578 Joined: |
So why would cells guide the process of mutation to produce these diseases? Or are mutations random, producing a wide range of effects?
Guided mutations does not mean strictly determined mutations. In the theory of environment-genes interrelation, there is always place for relative randomness in mutations.It seems the gap between the evollution theories is closing rapidly. It had proved beyond any doupt that stress causes genes mutations.So the mechanism for it exists in metazoa. Randomness and environmental information are useful to natural life, so are used equally well by nature, most propably radomness more often in monocells, while in metazoa, where neural system is developed guidance is more propable.
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Taq Member Posts: 10085 Joined: Member Rating: 5.6
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Guided mutations does not mean strictly determined mutations. What it means is that you have an ad hoc explanation for guided mutations. The same process produces beneficial, neutral, and detrimental mutations and there is no way to predict which type of mutation it will produce next. They are OBSERVED to be random with respect to fitness.
It seems the gap between the evollution theories is closing rapidly. It had proved beyond any doupt that stress causes genes mutations.So the mechanism for it exists in metazoa. Randomness and environmental information are useful to natural life, so are used equally well by nature, most propably radomness more often in monocells, while in metazoa, where neural system is developed guidance is more propable. I see a lot of vague claims but zero evidence.
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