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Natural selection vs Genetic drift (Read 17871 times)
oh_noes
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Natural selection vs Genetic drift
Dec 24th, 2009 at 6:04pm
 
Thought I'd start up a new thread for some informed discussion. One aspect of evolution that I think gets overlooked by many is the role that genetic drift has to play.

I say understated because it's not that easy to see it in action. Genetic drift by definition isn't really noticable since it is survival neutral, the introduction of allele varients that are not really functionally different to to the other varients in the population.

However, the steady accumulation of new varients can give rise to interesting possibilities. It could be that, say, three new gene varients for three different genes, functionally the same as there other alleles, might combine to produce a hitherto unseen function. Should some new selection pressure arise this new function, one that has arisen entirely through drift and without apparent use could now become vital to survival.

Anyway, thats the basics, just figured I'd put genetic drift out there as an intersting topic for discussion. Is genetic drift as ignored as I believe it to be, or am I overestimating it's importance?
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Re: Natural selection vs Genetic drift
Reply #1 - Dec 24th, 2009 at 6:40pm
 
oh_noes wrote on Dec 24th, 2009 at 6:04pm:
Thought I'd start up a new thread for some informed discussion. One aspect of evolution that I think gets overlooked by many is the role that genetic drift has to play.

I say understated because it's not that easy to see it in action. Genetic drift by definition isn't really noticable since it is survival neutral, the introduction of allele varients that are not really functionally different to to the other varients in the population.

However, the steady accumulation of new varients can give rise to interesting possibilities. It could be that, say, three new gene varients for three different genes, functionally the same as there other alleles, might combine to produce a hitherto unseen function. Should some new selection pressure arise this new function, one that has arisen entirely through drift and without apparent use could now become vital to survival.

Anyway, thats the basics, just figured I'd put genetic drift out there as an intersting topic for discussion. Is genetic drift as ignored as I believe it to be, or am I overestimating it's importance?


Show me the absolute evidence for "genetic drift"?  Show me where this has been demonstrated in any scientific method experiment?

Neither "natural selection" nor "genetic drift" have been proven to be scientific, because they are both just based on observations and opinions.  There is no trail of genetic drift that ever would go beyond the genetic structural framework of any genealogy. 

There is no real evidence of any "fish" ever crawling on land and breathing air, growing legs. There is no possible way for this to happen.  And if it were to happen there would be "many" fish that did this.  If it works at all, then it always works and you would see this today in many species of fish with legs developing, for no reason.

I don't know if you have any idea how insane this sounds to me, realizing that all you have is a religious belief and no evidence.
Read this feculence and tell me that it isn't just more dumb ass believers and their opinions.  This is laughable and so low intelligence that it is hard to believe people are this stupid.


http://www.sciencedaily.com/releases/2008/10/081015144123.htm

The reality is this creature is a unique creature that arrived fully developed and there is no trail of it ever evolving.  It is not transitional, because there are no transitional parts.
There is no evidence of anything before or after this species.
Nothing but belief and religious fervor of these pseudo scientists.

This fish has no meaning, without DNA to show any tie to any other creature.

There are far more extinct species, just like this the came, remained the same for millions of years, then went extinct.
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glowingape
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Re: Natural selection vs Genetic drift
Reply #2 - Dec 24th, 2009 at 7:03pm
 
oh_noes wrote on Dec 24th, 2009 at 6:04pm:
Thought I'd start up a new thread for some informed discussion. One aspect of evolution that I think gets overlooked by many is the role that genetic drift has to play.

I say understated because it's not that easy to see it in action. Genetic drift by definition isn't really noticable since it is survival neutral, the introduction of allele varients that are not really functionally different to to the other varients in the population.

However, the steady accumulation of new varients can give rise to interesting possibilities. It could be that, say, three new gene varients for three different genes, functionally the same as there other alleles, might combine to produce a hitherto unseen function. Should some new selection pressure arise this new function, one that has arisen entirely through drift and without apparent use could now become vital to survival.

Anyway, thats the basics, just figured I'd put genetic drift out there as an intersting topic for discussion. Is genetic drift as ignored as I believe it to be, or am I overestimating it's importance?

Actually -- both are quite vital components for population survival... As genetic drift as natural selection. Trough time genetic... Um... "information" changes, which change our structure, make us more resilient to one form of disease, and natural selection to weed out the ones, that didn't get the mutations.

One of the most perfect (and most graphic) examples for those would most likely be the black plague...
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Re: Natural selection vs Genetic drift
Reply #3 - Dec 24th, 2009 at 10:27pm
 
glowingape wrote on Dec 24th, 2009 at 7:03pm:
oh_noes wrote on Dec 24th, 2009 at 6:04pm:
Thought I'd start up a new thread for some informed discussion. One aspect of evolution that I think gets overlooked by many is the role that genetic drift has to play.

I say understated because it's not that easy to see it in action. Genetic drift by definition isn't really noticable since it is survival neutral, the introduction of allele varients that are not really functionally different to to the other varients in the population.

However, the steady accumulation of new varients can give rise to interesting possibilities. It could be that, say, three new gene varients for three different genes, functionally the same as there other alleles, might combine to produce a hitherto unseen function. Should some new selection pressure arise this new function, one that has arisen entirely through drift and without apparent use could now become vital to survival.

Anyway, thats the basics, just figured I'd put genetic drift out there as an intersting topic for discussion. Is genetic drift as ignored as I believe it to be, or am I overestimating it's importance?

Actually -- both are quite vital components for population survival... As genetic drift as natural selection. Trough time genetic... Um... "information" changes, which change our structure, make us more resilient to one form of disease, and natural selection to weed out the ones, that didn't get the mutations.

One of the most perfect (and most graphic) examples for those would most likely be the black plague...



This is one of those "slogans" of evodelusionism that has no evidence and absolutely no use of the scientific method.
People survive the plague, because of genetics and for no other reason.   

We can conjecture all day about things like this but you don't have a f**king clue what you are talking about.

It has nothing to do with evolution, not a even a little.

This is not evidence it is f**king opinions based on belief that you would project your f**king beliefs on genetics. Genetics only shows the need for survival. That is even in the 30,000 code changes cause by smoking. The "doctor" said that the persons DNA shows it wants to survive. It doesn't want to evolve.  That is what is shown in the DNA.

Where is your absolute evidence for evolution, that is irrefutable and has no other plausibilities and no human emotional mental garbage opinions in it?
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Re: Natural selection vs Genetic drift
Reply #4 - Dec 25th, 2009 at 1:32am
 
glowingape wrote on Dec 24th, 2009 at 7:03pm:
oh_noes wrote on Dec 24th, 2009 at 6:04pm:
Thought I'd start up a new thread for some informed discussion. One aspect of evolution that I think gets overlooked by many is the role that genetic drift has to play.

I say understated because it's not that easy to see it in action. Genetic drift by definition isn't really noticable since it is survival neutral, the introduction of allele varients that are not really functionally different to to the other varients in the population.

However, the steady accumulation of new varients can give rise to interesting possibilities. It could be that, say, three new gene varients for three different genes, functionally the same as there other alleles, might combine to produce a hitherto unseen function. Should some new selection pressure arise this new function, one that has arisen entirely through drift and without apparent use could now become vital to survival.

Anyway, thats the basics, just figured I'd put genetic drift out there as an intersting topic for discussion. Is genetic drift as ignored as I believe it to be, or am I overestimating it's importance?

Actually -- both are quite vital components for population survival... As genetic drift as natural selection. Trough time genetic... Um... "information" changes, which change our structure, make us more resilient to one form of disease, and natural selection to weed out the ones, that didn't get the mutations.

One of the most perfect (and most graphic) examples for those would most likely be the black plague...


Another popular example is the Jar-Marble analogy

The process of genetic drift can be illustrated using 20 marbles in a jar to represent 20 organisms in a population. Half of them are red and half blue, and both colors correspond to two different gene alleles in the population. The offspring they reproduce for the next generation are represented in another jar. In each new generation the organisms reproduce at random. To represent this reproduction, randomly select any marble from the original jar and deposit a new marble with the same color as its "parent" in the second jar. Repeat the process until there are 20 new marbles in the second jar. The second jar will then contain a second generation of "offspring", 20 marbles of various colors. Unless the second jar contains exactly 10 red and 10 blue marbles, there will have been a purely random shift in the allele frequencies.
Repeat this process a number of times, randomly reproducing each generation of marbles to form the next. The numbers of red and blue marbles picked each generation will fluctuate: sometimes more red, sometimes more blue. This fluctuation is genetic drift – a change in the population's allele frequency resulting from a random variation in the distribution of alleles from one generation to the next.

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oh_noes
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Re: Natural selection vs Genetic drift
Reply #5 - Dec 25th, 2009 at 11:55am
 
glowingape, that is pretty much what I had in mind with my example. The immunity for black plague obviously arises through a mutation of some kind (or series of mutations), but its chance of spreading through the population is influenced by selection pressure. If none is present then your marbles example is perfect. That would actually model genetic drift extremely well for ease of understanding.

At such a time that black plague is not prevalent in a population it is possible that immunity to it would still evolve and spread through the population simply through chance in the same way as any other allele can upon arising. Only when black plague started to spread would natural selection kick in to spread immunity faster (or rather, to remove those unfortunate enough not to have it, thus reducing population size). The increased fitness provided by immunity is the positive selection pressure.

The mutation to provide immunity for black plague is far more likely to arise in the millions of years before black plague strikes than during an outbreak, but it is only during hte outbreak itself that the repercussions are noticed. The selection pressure speeds up fixation, as it were.

I suspect that the majority of genes do not get fixed through genetic drift but that huge diversity accumulates within the population, all the better for survival of the species as this provides a better chance of adaptation to some new selection pressure.
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Re: Natural selection vs Genetic drift
Reply #6 - Dec 25th, 2009 at 2:30pm
 
oh_noes wrote on Dec 25th, 2009 at 11:55am:
glowingape, that is pretty much what I had in mind with my example. The immunity for black plague obviously arises through a mutation of some kind (or series of mutations), but its chance of spreading through the population is influenced by selection pressure. If none is present then your marbles example is perfect. That would actually model genetic drift extremely well for ease of understanding.

At such a time that black plague is not prevalent in a population it is possible that immunity to it would still evolve and spread through the population simply through chance in the same way as any other allele can upon arising. Only when black plague started to spread would natural selection kick in to spread immunity faster (or rather, to remove those unfortunate enough not to have it, thus reducing population size). The increased fitness provided by immunity is the positive selection pressure.

The mutation to provide immunity for black plague is far more likely to arise in the millions of years before black plague strikes than during an outbreak, but it is only during hte outbreak itself that the repercussions are noticed. The selection pressure speeds up fixation, as it were.

I suspect that the majority of genes do not get fixed through genetic drift but that huge diversity accumulates within the population, all the better for survival of the species as this provides a better chance of adaptation to some new selection pressure.


The mutation(s) for plague immunity would have spread very quickly during the first few generations after the plague sweeped through Europe.  It's probably still kicking about in a large number of people, and as has already mentioned unless theres any other advantages from it it'll just 'slush' about in the gene pool's of the various European countries.

Just thought i'd add in that quick thing, new to the boards and still poking about.
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oh_noes
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Re: Natural selection vs Genetic drift
Reply #7 - Dec 25th, 2009 at 2:45pm
 
That would depend on how far along the genes were to fixation in the population. Those with natural immunity have increased fitness and so the probability of their genes spreading would increase. The rate of spread would be dictated by the advantage conferred, and i don't know the figures.

I would suggest that the genes failed to become fixed because it is now hypothesized that black plague immunity might confer immunity, or at least some resistance, to HIV, but it is also clear that many Europeans do not have this resistance.

The gene is likely to be wide spread however and could well be on it's way to fixation.



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Re: Natural selection vs Genetic drift
Reply #8 - Dec 25th, 2009 at 2:58pm
 
oh_noes wrote on Dec 25th, 2009 at 2:45pm:
That would depend on how far along the genes were to fixation in the population. Those with natural immunity have increased fitness and so the probability of their genes spreading would increase. The rate of spread would be dictated by the advantage conferred, and i don't know the figures.

I would suggest that the genes failed to become fixed because it is now hypothesized that black plague immunity might confer immunity, or at least some resistance, to HIV, but it is also clear that many Europeans do not have this resistance.

The gene is likely to be wide spread however and could well be on it's way to fixation.


Your right, appologies for being a bit imprecise, put it down to seasonal intke of food.

But yes, the rate of spread would depend on how many people had the mutation(s), and also if there was one instance of a beneficial mutation or more than one.  Also bear in mind that after something like that there would likely have been pressure for lots of babies (with lots of oportunities for the genes to be passed on).  However this is a fair amount of assuming on our part, and not theres also the fact i'm talking outside of my specialism.

On to something i can say clearly, and you'll need to accept my appologies for not having a link sorted in relation to this.  The mutated allele that codes for cystic fibrosis is thought to pose an advantage to fertility, i.e. if you are a carrier it improves your fertility.  Now i'm a bit shakey on the specifics as it was a while ago that i did this (i dabbled in first year genetics and evolution at uni) but it was when i did a number of lectures on genetic disorders.  I will dig about on wiki to see if i can find a place for you to start on this.
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Re: Natural selection vs Genetic drift
Reply #9 - Dec 25th, 2009 at 3:06pm
 
As promised, here is a link: http://en.wikipedia.org/wiki/Cystic_fibrosis

The section you want is theories about prevalence, it's got the susual citations if you want to double check it.
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Re: Natural selection vs Genetic drift
Reply #10 - Dec 25th, 2009 at 3:52pm
 
Volcano Girl wrote on Dec 25th, 2009 at 3:06pm:
As promised, here is a link: http://en.wikipedia.org/wiki/Cystic_fibrosis

The section you want is theories about prevalence, it's got the susual citations if you want to double check it.


I take it that you see evolution when there is none.  You also do not understand what real evidence is.

Sitting around and making up "ideas" about how things work is not evidence.  Do you understand the difference between real empirical evidence and beliefs being bantered about.

Opinions are not evidence.  It does not matter who's opinions they are.

it is difficult for me to be dealing with brainwashed people who have no idea they are brainwashed.

You all sound like nut jobs.
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Re: Natural selection vs Genetic drift
Reply #11 - Dec 25th, 2009 at 4:02pm
 
Volcano Girl wrote on Dec 25th, 2009 at 3:06pm:
As promised, here is a link: http://en.wikipedia.org/wiki/Cystic_fibrosis

The section you want is theories about prevalence, it's got the susual citations if you want to double check it.


Quite an interesting article that. I got particularly interested in the proposed heterozygous advantages that could lead to the spread of a potentially deleterious allele through the population. The link to diarrhea and lactose tolerance sounded the most plausible to me so I read the cited article at

http://www.nature.com/ejhg/journal/v15/n3/full/5201749a.html

Clearly it is an area that requires further research and is not even close to resolved, definitely a great example of propogation of a mutation through the population that cannot be said to be necessarily negative or positive, and indeed emphasising natural selection.
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Re: Natural selection vs Genetic drift
Reply #12 - Dec 25th, 2009 at 4:08pm
 
oh_noes wrote on Dec 25th, 2009 at 4:02pm:
Volcano Girl wrote on Dec 25th, 2009 at 3:06pm:
As promised, here is a link: http://en.wikipedia.org/wiki/Cystic_fibrosis

The section you want is theories about prevalence, it's got the susual citations if you want to double check it.


Quite an interesting article that. I got particularly interested in the proposed heterozygous advantages that could lead to the spread of a potentially deleterious allele through the population. The link to diarrhea and lactose tolerance sounded the most plausible to me so I read the cited article at

http://www.nature.com/ejhg/journal/v15/n3/full/5201749a.html

Clearly it is an area that requires further research and is not even close to resolved, definitely a great example of propogation of a mutation through the population that cannot be said to be necessarily negative or positive, and indeed emphasising natural selection.


Yep, i had a little poke about there myself, nothing as intensive it seems as you.  I do appear to have been a bit off, unless my lecture was before this paper came out (which is very likely).
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Re: Natural selection vs Genetic drift
Reply #13 - Dec 25th, 2009 at 4:12pm
 
I doubt it, it's so little understood yet that your information could still be considered up to date. We look at the frequency of the allele in the population and note that there is an anomaly in Europe, the only explanations are increased mutation rates or a positive selection pressure (or lack of a negative one).

We can say for certain that something in Europe has led to increased fitness (and therefore fertility one could argue, depending on definition), the cause is still somewhat of a mystery.
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Re: Natural selection vs Genetic drift
Reply #14 - Dec 25th, 2009 at 6:02pm
 
Volcano Girl wrote on Dec 25th, 2009 at 2:58pm:
oh_noes wrote on Dec 25th, 2009 at 2:45pm:
That would depend on how far along the genes were to fixation in the population. Those with natural immunity have increased fitness and so the probability of their genes spreading would increase. The rate of spread would be dictated by the advantage conferred, and i don't know the figures.

I would suggest that the genes failed to become fixed because it is now hypothesized that black plague immunity might confer immunity, or at least some resistance, to HIV, but it is also clear that many Europeans do not have this resistance.

The gene is likely to be wide spread however and could well be on it's way to fixation.


Your right, appologies for being a bit imprecise, put it down to seasonal intke of food.

But yes, the rate of spread would depend on how many people had the mutation(s), and also if there was one instance of a beneficial mutation or more than one.  Also bear in mind that after something like that there would likely have been pressure for lots of babies (with lots of oportunities for the genes to be passed on).  However this is a fair amount of assuming on our part, and not theres also the fact i'm talking outside of my specialism.

On to something i can say clearly, and you'll need to accept my appologies for not having a link sorted in relation to this.  The mutated allele that codes for cystic fibrosis is thought to pose an advantage to fertility, i.e. if you are a carrier it improves your fertility.  Now i'm a bit shakey on the specifics as it was a while ago that i did this (i dabbled in first year genetics and evolution at uni) but it was when i did a number of lectures on genetic disorders.  I will dig about on wiki to see if i can find a place for you to start on this.


WTF does this have to do with evodelusionism? 
Where is your absolute evidence, irrefutable and physical.

This is bovine feculence, conjecture by idiot brainwashed and now we can ad arrogance and delusional believers.

It is clear to any sane person that you take all sorts of fantasy ideas and run a muck with them, when there is no scientific evidence to back it.

No creature has ever evolved into an entirely new species, much less a genus or "clad".  No fish has ever evolved into a reptile.  No reptile has ever become a bird or mammal. No creature has violated the laws of genetics and become something totally new. 



There are two things contained in evidence of the fossils as badly dated as they are.

1/ Creatures came into existence, remained the same, in some cases over 50,000,000 years (or much more by some dating systems) by your dating, and then went extinct when the environment was not suitable for their existecne.

2/ We have aprox 90% of the existing vertebrate fossils of the non bird creatures now living. They look identical to the ones still living.  Because we have the huge majority of fossils of current creatures, up to 125,000,000 years old, this shows the fossilization is more common than the religious believer in the pseudo science of evolution want to accept.

There exists no magical processes, or mystical voodoo in science.  You are supposed to just look at evidence and transh your, garbage Evodelusionism religious idea. This is the nature of human emotional mental garbage, contained in beliefs that are not founded in reality nor science.
Evolution is a pseudo science and causes people to be stupid. Beliefs destroy credibility.





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