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Member (Idle past 1736 days) Posts: 2161 From: Cambridgeshire, UK. Joined: |
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Author | Topic: Doesn't Natural Selection lead to Specified Complexity? | |||||||||||||||||||||||
Taq Member Posts: 10302 Joined: Member Rating: 7.1 |
Having a relationship which is nuetral (as you I think put it) or having an absence of a relationship amount to the same thing i.e. those mutations are not acted upon by natural selection. They are not the same thing. There is no relationship between a mutation that occurs in an ostrich and deep sea environments because an ostrich does not live in a deep sea environment. However, each and every mutation that occurs in an ostrich offspring (including neutral ones) have a relationship with the environment they do live in. For neutral mutations, this relationship causes the ratio of neutral mutations to stay the same on average. Natural selection is all about the probability of a mutation being passed on. For neutral mutations, natural selection produces a 50-50 probability.
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Peter Member (Idle past 1736 days) Posts: 2161 From: Cambridgeshire, UK. Joined: |
It won't be 50-50 if there are other mutations which are being selected for or against.
The indivuals with the 'selectable' mutations will affect the gene distribution in the population regardless of any nuetral mutations present. Nuetral meaning that they have no affect on fitness ... which in turn means they have no relationship to the environment. To detect the nuetrality investigators would need to reference the environment, but that's not the same as there being a relationship between a nuetral mutation and the environment. The ostrich mutation MIGHT have a relationship to a deep sea environment (if for example it changed the ability to absorb oxygen from sea water) but not to the environment that the ostrich IS in.
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Taq Member Posts: 10302 Joined: Member Rating: 7.1 |
It won't be 50-50 if there are other mutations which are being selected for or against. All population genetics assume an ideal population. A neutral mutation has the same chance of being linked to a detrimental or beneficial allele so the it does average out to 50-50 for all neutral mutations in an ideal population.
Nuetral meaning that they have no affect on fitness ... which in turn means they have no relationship to the environment. I have addressed this quite a few times. This is false. It is the relationship between the mutation and the environment that determines the effect on fitness, even if that effect results in no net change.
The ostrich mutation MIGHT have a relationship to a deep sea environment (if for example it changed the ability to absorb oxygen from sea water) but not to the environment that the ostrich IS in. Right. So the neutrality of a mutation is determined by the relationship between the mutation and the environment that the organism is in.
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PaulK Member Posts: 17919 Joined: Member Rating: 6.7 |
quote:You were definitely trying to change the subject, which was how events that cause drift are part of the environment as you defined it. Why you chose to dispute that, when you stated that ALL events are part of the environment, I suppose I'll never know. And since I explained how events in the environment can cause drift I suggest that you deal with the point rather than digging yourself even deeper by making more false assertions.
quote: Obviously you don"t understand drift, which is all about how the new alleles created by mutation rise and decline in frequency, apart from selection.
quote:Because given that view, there is nothing special about being deterministic. Everything is. Even freak accidents. quote: Nevertheless, it is, and it is in there, lumped together with selection.
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Peter Member (Idle past 1736 days) Posts: 2161 From: Cambridgeshire, UK. Joined: |
Drift:
Could you perhaps give me a reference or short description of this process of drift? My understanding is that 'drift' referes to the change in gene distribution in a population which is not associated with any selective pressure. That would seem to be purely about the random mutations. I would also assume that some mutations are more likely than others (since we are talking about chemistry when it comes down to it). Drift (in not being influenced by the environment) must be subordinate to selective change in gene distribution (where selective pressures exist). So this is used to explain how, in the absence of any obvious selective pressure, gene distribution still changes. It's more to do with the prevelance of a specific, nuetral change than aything else. So it isn't a process. Determinism: I didn't say that determinism was special in any way. There is no such thing a as a freak accident -- there are situations for which the number of variables are so vast, with such complicated interactions that we are unable to comprehend them. Sometimes we have to settle for 'random' or 'stochastic' or 'chaotic' I can see drift as a function of genetic mutation, but not as a process which relates environment to genetic mutation.
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Peter Member (Idle past 1736 days) Posts: 2161 From: Cambridgeshire, UK. Joined: |
Taq writes:
It won't be 50-50 if there are other mutations which are being selected for or against. All population genetics assume an ideal population. A neutral mutation has the same chance of being linked to a detrimental or beneficial allele so the it does average out to 50-50 for all neutral mutations in an ideal population.
But surely you have to include the possibility that the nuetral mutation occurs alone in some individuals. So the split can never be 50-50. If there are three possibilities surely there is a 60% chance that the nuetral mutation will continue (2 out of 3 cases).
Nuetral meaning that they have no affect on fitness ... which in turn means they have no relationship to the environment. I have addressed this quite a few times. This is false. It is the relationship between the mutation and the environment that determines the effect on fitness, even if that effect results in no net change.
See below The ostrich mutation MIGHT have a relationship to a deep sea environment (if for example it changed the ability to absorb oxygen from sea water) but not to the environment that the ostrich IS in. Right. So the neutrality of a mutation is determined by the relationship between the mutation and the environment that the organism is in.
WE determine nuetrality by relating it to the environment -- or not. If we cannot find a relationship to the environment we term the mutation as nuetral wrt fitness. We determine that because there is no relationship to the environment, surely.
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PaulK Member Posts: 17919 Joined: Member Rating: 6.7 |
quote: Although you offer a correct definition it is obvious that you do NOT understand it. Nobody who understood it could say that it is "purely about the random mutations". It must be about how those mutations spread through a population - or decline to extinction. Or do you imagine that a neutral mutation becomes fixed by independently occurring in so many individuals that it takes over the population?
quote: Why not ?
quote: Perhaps instead of making assertions apparently based on nothing more than your own, personal idiosyncratic definitions you might try to discuss matters more reasonably.
quote: And, as shown above the way you see drift is wrong, as shown by the definition you, yourself offered.
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Peter Member (Idle past 1736 days) Posts: 2161 From: Cambridgeshire, UK. Joined: |
At the top of your post you said I defined drift correctly, and at the bottom you said I defined it incorrectly.
How do you define drift? If the mutations are neutral wrt environment, then they can ONLY become fixed due to prevalence OR being co-present with selectable mutations. Niether situation represents a process (i.e. a set of defined steps and/or functions -- or is that an incorrect definition of process). Do you disagree that, for example, weather patterns could be predicted if we had a perfect model of the weather systems around the earth? Do you disagree that the reason we cannot create a perfect model of weather patterns is that the system is too complex for us to fully understand?
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PaulK Member Posts: 17919 Joined: Member Rating: 6.7 |
quote: That is untrue. I said that you offered a correct definition but utterly failed to understand it. And I explained the error in your understanding, too. Did you actually bother to read my post ?
quote: If by "prevalence" you mean "being very common" then it's sort of redundant - and doesn't deal with HOW that mutant form becomes prevalent. If you mean something else, then you need to explain it. The real point is that there are "chance" variations in gene distribution and they can and do add up to fixation on a regular basis.
quote: I think that you are trying to use the wrong definition. And - at the level you appear to want to use, even natural selection wouldn't qualify for your definition. You certainly can't break it down to events in individual lives and still have well-defined steps.
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Ryan Junior Member (Idle past 4946 days) Posts: 5 Joined: |
Peter writes:
Since Natural Selection can be viewed as a filter over the random mutations that we KNOW accur in biological systemscarried forward. Explain to me how you "Know"
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Peter Member (Idle past 1736 days) Posts: 2161 From: Cambridgeshire, UK. Joined: |
Because there are a vast number of scientific studies reported in peer reviewed journals that discuss, detail and describe them.
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Peter Member (Idle past 1736 days) Posts: 2161 From: Cambridgeshire, UK. Joined: |
A mutation can become prevalent in a population for one of two reasons:
1) the mutation itself is in some-way preferred (maybe there is a predisposition towards a certain type of 'error' in some genes). Not saying there is, just saying that's a possible cause. 2) the mutation occurs in indivdiuals who also have a beneficial mutation. I DID read your post, there was just very little in it. At a very high level one could draw a flow-chart for natural selection. At no level could you describe drift as any kind of sequence or logic. So: I asked for you to define drift -- you have basically accepted my definition, but stated that I don't understand my own definition of drift. A definition which, by definition, defines the way I think about drift. In many ways I don't see what you want me to change in my thinking. All I have said is that the gene distribution in a population is an accumulation of genetic changes dominated by natural selection, but have accepted that 'drift' plays it's part. Ignore drift ... since it is not a filter and therefore not relevant to my OP. Natural Selection can act as a filter over the gene changes, and therefore lead to 'specificity' thereby elliminating 'specified complexity' as a pillar of ID. Ignore determinism. You don't agree with my position on that, that's OK. I simply have a 'not playing dice with the universe' kind-of attitude.
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Dr Adequate Member Posts: 16113 Joined: |
A mutation can become prevalent in a population for one of two reasons: 1) the mutation itself is in some-way preferred (maybe there is a predisposition towards a certain type of 'error' in some genes). Not saying there is, just saying that's a possible cause. 2) the mutation occurs in indivdiuals who also have a beneficial mutation. 3) Genetic drift.
In many ways I don't see what you want me to change in my thinking. All I have said is that the gene distribution in a population is an accumulation of genetic changes dominated by natural selection . Quantitatively, this isn't the case. not only is most genetic variation due to drift, but also in most cases drift will beat selection. A new mutation which confers an n% advantage has (for small n) a 2n% chance of going on to be fixed by selection*; in the other cases it will be eliminated by genetic drift despite its advantages.
* Neglecting the cases in which selection wouldn't lead to fixation anyway, but to a stable equilibrium, as in the case of the sickle-cell allele. It is true that selection acting on beneficial mutations is responsible for pretty much everything of interest; in particular, for the adaptation of organisms to their environment which deceives creationists into inferring design.
Ignore drift ... since it is not a filter and therefore not relevant to my OP. It isn't, but that's no reason to speak as though it doesn't exist or as though it isn't what it in fact is. Edited by Dr Adequate, : No reason given.
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PaulK Member Posts: 17919 Joined: Member Rating: 6.7 |
quote: Yet you obviously missed the point that there is a third way - some genes just spread by "chance". Which, when the numbers are considered, is far more likely in most cases than the idea that a mutation occurs fixation by occurring independently enough times to take over the population (your first suggestion),
quote: Sure you could, at a high enough level. The only difference between drift and selection is that drift occurs more slowly because it relies on pure "chance" rather than biased "chance".
quote: And yet it does not. The way that you think about drift - the two choices you list above - is NOT inherent in the definition.
quote: THe problem is that you wanted to portray natural selection as deterministic. And yet it is not so in a simple way - there are many factors affecting the outcome which are independent of selection. They are modeled as chance events because they ARE independent of selection. And so you chose to incorporate such events by appealing to universal determinism. And yet these events are the events which cause drift (certainly when acting against selection, and I would say even when acting with it).
quote: That's not the issue. It's the inconsistency in your views that is the problem. You can't appeal to universal determinism to make natural selection deterministic without doing exactly the same to drift - and making drift equivalent to selection (since some drift is INCLUDED in your natural selection).
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Peter Member (Idle past 1736 days) Posts: 2161 From: Cambridgeshire, UK. Joined: |
I think you are confusing natural selection with evolution as a whole.
Since I am interested in the specifying capability of natural selection, and since drift can be viewed as 'chance' then for the purposes of THIS discussion we can neglect drift. Check back -- an answer you gave to one of my questions means that you acknowledge the determinism of natural selection. Your third option for drift being 'purely by chance' is insufficient for explanation. If a particular mutation becomes prevalent then there WILL be a reason for that.
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