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Author Topic:   Are mutations enough to explain natural selection?
Eximius
Inactive Member


Message 1 of 95 (28181)
12-31-2002 7:05 AM


Let me begin by saying that I am an evolutionist. I understand that if a mutation is favourable to an organism, that organism will tend to produce more offspring and the mutation will spread. But surely most mutations (apart from the odd useful macromutation) wouldn't help an organism so much that it increases its chances of survival or reproduction.

For example, if a mutation gave a bird a slightly longer wingspan, the bird might fly more efficiently and catch more food, but does this ensure that the gene for long wing is passed on more than the gene for short wing? A bird that caught 9 fish a day would probably reproduce just as much as a bird that caught 10 fish a day.

Perhaps natural selection is only effective when resources are limited and even slightly helpful mutations mean the difference between life and death, or between reproduction and lack of.

Thoughts?

------------------
"I'm rather less interested in what people think than in what's true"
- Richard Dawkins


Replies to this message:
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Gzus
Inactive Member


Message 2 of 95 (28187)
12-31-2002 9:42 AM


Sure, the bird that caught 9 fish would survive just as the bird that caught 10, but that's a positive step. the important fact is that 'bird 10' survives, hence his mutated gene survives. he breeds with the other birds until the gene becomes common among the population. Now imagine, that a few years later, there's a really bad winter, more of the birds with the 'bird 10' gene will survive, hence the average wingspan of the population increases and the popylation has evolved.

Replies to this message:
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Eximius
Inactive Member


Message 3 of 95 (28193)
12-31-2002 10:36 AM
Reply to: Message 2 by Gzus
12-31-2002 9:42 AM


Let me use another example that doesn't involve competition. How would natural selection favour a slightly larger skin flap in colugos, gliding possums, etc if an advantageous mutation merely allowed an individual to glide an extra metre?

------------------
"I'm rather less interested in what people think than in what's true"
- Richard Dawkins


This message is a reply to:
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Gzus
Inactive Member


Message 4 of 95 (28196)
12-31-2002 10:48 AM


well, that mutation was spread among the flying possoms until such a time as it was needed, maybe it was made more advantageous in combination with another mutation which made larger flight spans even more desirable. Perhaps a disaster then killed off a large proportion of the mort short-flighted creatures. There are many possible explanations, but it is quite reasonable to say that each situation during which an evolution occurs is quite unique.

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Coragyps
Member
Posts: 5515
From: Snyder, Texas, USA
Joined: 11-12-2002
Member Rating: 3.8


Message 5 of 95 (28198)
12-31-2002 11:43 AM
Reply to: Message 4 by Gzus
12-31-2002 10:48 AM


The way I understand this issue is that it's sort of like compound interest at the bank: a very slight advantage carried over a thousand generations, say, translates into a major spread through the population. If that one-meter-further flight resulted in 0.01% more of the possums that could do it surviving to breed, the trait (assuming it's heritable, of course) would take over surprisingly soon. And nature isn't in much of a hurry.

This message is a reply to:
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Fred Williams
Member (Idle past 3412 days)
Posts: 310
From: Broomfield
Joined: 12-17-2001


Message 6 of 95 (28225)
12-31-2002 5:41 PM
Reply to: Message 5 by Coragyps
12-31-2002 11:43 AM


I had some spare time this afternoon and wanted to address Eximus’ post. Frankly the responses Eximius received were completely bogus.

quote:

But surely most mutations (apart from the odd useful macromutation) wouldn't help an organism so much that it increases its chances of survival or reproduction.

The vast majority of mutations fall in this category.

We’ve debated here many times whether or not there are any mutations that add new, useful information to a population. Evolutionists struggle to provide examples, and of those provided I have yet to see a provocative one. Yet there should be a myriad of water-tight examples for evolution to be true.

quote:

For example, if a mutation gave a bird a slightly longer wingspan, the bird might fly more efficiently and catch more food, but does this ensure that the gene for long wing is passed on more than the gene for short wing? A bird that caught 9 fish a day would probably reproduce just as much as a bird that caught 10 fish a day.

This is a good point.

quote:

Gzus: Sure, the bird that caught 9 fish would survive just as the bird that caught 10, but that's a positive step. the important fact is that 'bird 10' survives, hence his mutated gene survives. he breeds with the other birds until the gene becomes common among the population.

This is simply nonsense. You start by agreeing with Eximius that there is no selective value, then you turn around and say there *is* selective value!

quote:

Gzus: The important fact is that 'bird 10' survives, hence his mutated gene survives. he breeds with the other birds until the gene becomes common among the population.

Again, this is nonsense, followed by this nonsense:

quote:
Coragyps: If that one-meter-further flight resulted in 0.01% more of the possums that could do it surviving to breed, the trait (assuming it's heritable, of course) would take over surprisingly soon.

First, if the mutation is neutral (which part of Gzus agrees is ) then the odds it survives and fixates in a population is equal to its initial frequency, according to evolutionists. So in a population of 100,000, the odds are 1 in 100,000 it will survive and fix. You both act as if it’s unity.

What if it does have a selective value? Evolutionists typically consider the odds of a beneficial mutation surviving to be 1 in 50. This is an underestimate because this assumes an atypically high selective value of .1 (Gaylord Simpson believes the average positive selection value is .01). Using the more reasonable selective value the odds are 1 in 500.

But that is not the only problem. The rate at which a mutation can fix in a population is governed by its capacity for reproduction. Using all kinds of favorable assumptions, the renowned evolutionist Haldane showed that in vertebrates, at most just 1 beneficial mutation could fixate in a population once every 300 generations! The only way to reduce this number is to increase the selective value, but when you do this the burden on reproductive capacity increases! Haldane showed you had to keep the selective value low to prevent species extinction.

Where does all this lead? To one inescapable conclusion: Evolution is one big fairytale.

Sources:
Theoretical Aspects of Population Genetics, Kimura & Ohta, 1971, p 3
Evolutionary Genetics, Maynard Smith, 1989, p 161-162
Evolutionary Biology, Douglas Futuyma, 1998, p 298
Haldane, “The Cost of Natural Selection”, 1957, p 520-521


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Replies to this message:
 Message 7 by Zhimbo, posted 12-31-2002 10:29 PM Fred Williams has responded
 Message 8 by Eximius, posted 12-31-2002 10:52 PM Fred Williams has responded
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 Message 11 by Gzus, posted 01-01-2003 5:10 PM Fred Williams has not yet responded
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Zhimbo
Member (Idle past 4568 days)
Posts: 571
From: New Hampshire, USA
Joined: 07-28-2001


Message 7 of 95 (28230)
12-31-2002 10:29 PM
Reply to: Message 6 by Fred Williams
12-31-2002 5:41 PM


quote:

"First, if the mutation is neutral (which part of Gzus agrees is ) then the odds it survives and fixates in a population is equal to its initial frequency, according to
evolutionists. So in a population of 100,000, the odds are 1 in 100,000 it will survive and fix. You both act as if it?s unity."

Are you telling me that the %chance of an organism successfully passing on a new neutral mutation is inversely proportional to the population size?

While "unity" is certainly too high, just how did you get the 1/100,000 figure? Actually, I know how you calculated it -it's the inverse of the population size - but why do you think this calculation is valid? You have sources at the end of your post, so I assume you got this from one of them...care to elaborate?


This message is a reply to:
 Message 6 by Fred Williams, posted 12-31-2002 5:41 PM Fred Williams has responded

Replies to this message:
 Message 14 by Fred Williams, posted 01-02-2003 12:24 PM Zhimbo has responded

  
Eximius
Inactive Member


Message 8 of 95 (28232)
12-31-2002 10:52 PM
Reply to: Message 6 by Fred Williams
12-31-2002 5:41 PM


quote:
Originally posted by Fred Williams:
The rate at which a mutation can fix in a population is governed by its capacity for reproduction.

I understand that. The more advantageous a mutation is, the more likely the carrier of the mutation will survive to reproduction.

quote:
Originally posted by Fred Williams:
The only way to reduce this number is to increase the selective value, but when you do this the burden on reproductive capacity increases!

That's what I don't understand. Please help me out.
I apologise if this seems like a stupid question because it's obvious that most of the people on this forum have a greater understanding of this than me but I really want to understand how this works.

Thanks.

------------------
"I'm rather less interested in what people think than in what's true"
- Richard Dawkins


This message is a reply to:
 Message 6 by Fred Williams, posted 12-31-2002 5:41 PM Fred Williams has responded

Replies to this message:
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Eximius
Inactive Member


Message 9 of 95 (28233)
12-31-2002 10:53 PM
Reply to: Message 6 by Fred Williams
12-31-2002 5:41 PM


quote:
Originally posted by Fred Williams:
The rate at which a mutation can fix in a population is governed by its capacity for reproduction.

I understand that. The more advantageous a mutation is, the more likely the carrier of the mutation will survive to reproduction.

quote:
Originally posted by Fred Williams:
The only way to reduce this number is to increase the selective value, but when you do this the burden on reproductive capacity increases!

That's what I don't understand. Please help me out.
I apologise if this seems like a stupid question because it's obvious that most of the people on this forum have a greater understanding of this than me but I really want to understand how this works.

Thanks.


This message is a reply to:
 Message 6 by Fred Williams, posted 12-31-2002 5:41 PM Fred Williams has not yet responded

  
peter borger
Member (Idle past 6222 days)
Posts: 965
From: australia
Joined: 07-05-2002


Message 10 of 95 (28235)
01-01-2003 3:09 AM
Reply to: Message 1 by Eximius
12-31-2002 7:05 AM


Dear Eximius,
I recommend you to read some of my mailings first. Than you will understand that the concept of natural selection is NOT always valid. In particular at the level of the genome. As discussed before, genetic redundancies cannot be explained by natural selection. An example that has been discussed on this forum are the redundant alpha-actinin genes. To explain them one has to introduce neutral purifying selection. It is a contradictio in terminis. In the orthodox evolutionary community genetic redundancies have been met with a lot of disbelief, since they were found not to be associated with gene duplicaton and do not mutate more rapidly than essential genes. And thus, genetic redundancies defy evolutionism. In other words, evolution trough random mutations and selection cannot be true. I prefer the GUToB, since it is explanatory in these matters.

Best wishes,
Peter

(And don't read to much of Dawkins. It can be demonstrated that he doesn't even know the most elementary stuff on DNA. Above all things I prefer truth)

[This message has been edited by peter borger, 01-01-2003]


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Replies to this message:
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Gzus
Inactive Member


Message 11 of 95 (28254)
01-01-2003 5:10 PM
Reply to: Message 6 by Fred Williams
12-31-2002 5:41 PM


quote:
Originally posted by Fred Williams:

quote:

Gzus: Sure, the bird that caught 9 fish would survive just as the bird that caught 10, but that's a positive step. the important fact is that 'bird 10' survives, hence his mutated gene survives. he breeds with the other birds until the gene becomes common among the population.

This is simply nonsense. You start by agreeing with Eximius that there is no selective value, then you turn around and say there *is* selective value!


I am simply emphasising the fact that bird 10 survives. this is the first step. the second step is for bird 10 to reproduce and spread his genes, hence making his genes 'part' of the population (even if only a small number have it). Then, over time, his offspring may have more survival value hence outliving, reproducing the bird 9s and hence the average wingspan of the population increases. The 'trigger' which might make his offspring outlive the others could be a bad winter, a new predator, whatever, but until such a time, his genes have given the population the potential to evolve.

I don't see any nonsense there.


This message is a reply to:
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nator
Member (Idle past 726 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 12 of 95 (28289)
01-02-2003 9:42 AM
Reply to: Message 10 by peter borger
01-01-2003 3:09 AM


quote:

(And don't read to much of Dawkins. It can be demonstrated that he doesn't even know the most elementary stuff on DNA. Above all things I prefer truth)


Of course, one doesn't need any knowledge of DNA to understand that evolution occurs.


This message is a reply to:
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derwood
Member (Idle past 432 days)
Posts: 1457
Joined: 12-27-2001


Message 13 of 95 (28302)
01-02-2003 12:22 PM
Reply to: Message 12 by nator
01-02-2003 9:42 AM


quote:
Originally posted by schrafinator:
quote:

(And don't read to much of Dawkins. It can be demonstrated that he doesn't even know the most elementary stuff on DNA. Above all things I prefer truth)


Of course, one doesn't need any knowledge of DNA to understand that evolution occurs.


Indeed. Of course, we can use that type of argument against Borger and Williams, can't we?

Or, one can go here:

http://home.austarnet.com.au/stear/lesson_cre_ethics_rr.htm


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Fred Williams
Member (Idle past 3412 days)
Posts: 310
From: Broomfield
Joined: 12-17-2001


Message 14 of 95 (28303)
01-02-2003 12:24 PM
Reply to: Message 7 by Zhimbo
12-31-2002 10:29 PM


quote:

Zhimbo: Are you telling me that the %chance of an organism successfully passing on a new neutral mutation is inversely proportional to the population size?

No. I’m talking about the probability the mutation (or allele) survives and becomes fixed in the population.

quote:
Zhimbo: While "unity" is certainly too high, just how did you get the 1/100,000 figure? Actually, I know how you calculated it -it's the inverse of the population size - but why do you think this calculation is valid? You have sources at the end of your post, so I assume you got this from one of them...care to elaborate?

It’s a standard pop genetics equation. Fixation probability = initial frequency of allele (see Futuyma, p 300). If there are 100,000 organisms in a population, a new single mutation has a frequency of 1 in 100,000. This also is its odds of reaching 100% frequency over time.


This message is a reply to:
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Replies to this message:
 Message 21 by Zhimbo, posted 01-02-2003 2:10 PM Fred Williams has responded

  
Fred Williams
Member (Idle past 3412 days)
Posts: 310
From: Broomfield
Joined: 12-17-2001


Message 15 of 95 (28304)
01-02-2003 12:30 PM
Reply to: Message 8 by Eximius
12-31-2002 10:52 PM


quote:
quote:
--------------------------------------------------------------------------------
Originally posted by Fred Williams:
The only way to reduce this number is to increase the selective value, but when you do this the burden on reproductive capacity increases!
--------------------------------------------------------------------------------

That's what I don't understand. Please help me out.
I apologise if this seems like a stupid question because it's obvious that most of the people on this forum have a greater understanding of this than me but I really want to understand how this works.


It’s definitely not a stupid question. There is much to the answer, but I will try to give an abridged response. Imagine a mutation that is so vastly beneficial, its selective value is so high, that most of the population without it dies within a few generations. The surviving positive mutant begins to spread through the population, and the population begins to grow back to its initial size. The rate at which the population can return to its initial size is primarily governed by the number of offspring the organisms can produce per generation.

Thus, there are a certain number of deaths per generation that must occur to remove those organisms without the mutation. These deaths need to be replenished. How fast they can be replenished depends on the reproductive capacity of the organism. Much of that capacity has to pay for normal genetic deaths, while some excess is available to move the new positive mutation through the population over time. Even some receiving the advantageous mutation will die and need to be paid for (even though they are superior, they may still get hit by a rock, fall off a cliff, be a stuck up prude and not reproduce, get nailed with kryptonite, etc). ALL “genetic deaths” must be paid for and replinished by new offspring.

Conceptually speaking I hope you can now see why increasing the intensity of selection directly impacts the reproductive capacity and its ability to replinish and pay for the deaths.

Haldane showed that fitness is roughly e^(-30n^-1), where n is number of generations, and intensity of selection was roughly I = 30n^-1. As you can see, as intensity increases n decreases. This means fewer generations are available to pay the cost, putting a greater burden on reproductive capacity.

If you are really interested in this, you should go to a university library and get Haldane’s paper. I would also recommend Walter Remine’s book the Biotic Message, as he dedicates two chapters to this, plus a detailed appendix. Here is a good online discussion of this that covers some of the ground:

http://www.bearfabrique.org/Evolution/reminevictory

Also, my mutation rate article that thumps the notion of man/simian ancestry also deals with this issue:

http://www.evolutionfairytale.com/articles_debates/mutation_rate.htm


This message is a reply to:
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Replies to this message:
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