Ability to mutate is an adaptation

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Dougalbod
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Ability to mutate is an adaptation

Post by Dougalbod » Wed Oct 07, 2009 1:27 pm

Hi All

If DNA didn't mutate then there would be nothing for natural selection to work on - so no evolution and no ability to adapt to change.
So some level of mutation is essential. Does anybody know if there is any evidence to suggest that there are biochemical systems to promote mutation (at some low level) or does it rely on environmental effects to generate enough mutation? It seems to me that there must be some balance, the right amount of mutation and I'm curious about how cells manage this...


Dougal

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robsabba
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Post by robsabba » Wed Oct 07, 2009 2:05 pm

This is a very good question. Certainly life would have remained at a very "primitive" level without the ability of genetic material to mutate. The balance is primarily mantained by the accuracy of polymerases that copy DNA and by the efficiency of error correcting mechanisms. The environment also plays a role in creating errors in non-replicating DNA that can be copied later, though this is pretty much a non-changing parameter.

Many viruses, for example use very sloppy polymerases, which allows them to mutate much faster than organisms. This is a factor that makes it hard to keep up with vaccines (such as those for influenza).
Last edited by robsabba on Wed Oct 07, 2009 3:45 pm, edited 1 time in total.

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Post by gamila » Wed Oct 07, 2009 2:24 pm

If DNA didn't mutate then there would be nothing for natural selection to work on - so no evolution and no ability to adapt to change.


is this an admission that natural selection does not generate new species as colin leslie dean says

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Post by Dougalbod » Wed Oct 07, 2009 2:31 pm

No Gamila

We have evidence that DNA does mutate to produce different varieties of the same gene, so natural selection does have soemthing to work with.

Dougal

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Post by gamila » Wed Oct 07, 2009 2:40 pm

We have evidence that DNA does mutate to produce different varieties of the same gene, so natural selection does have soemthing to work with.

but NS does not generate the new gene
thus it canot generate new species=which have new genes

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Post by Dougalbod » Wed Oct 07, 2009 2:44 pm

Gamila

Your last post is vacuous, I'm sure you must be more intelligent than you seem...?

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Post by gamila » Wed Oct 07, 2009 2:52 pm

Your last post is vacuous, I'm sure you must be more intelligent than you seem...


you have said yourself that natural selection works with the mutated DNA
but NS t does not and cant generate that mutated DNA
what ever caused the DNA to mutate might be responsiblie for the generation of new species
but NS is not responible for the generation of new species- ie new genes
the logic is irrefutable

new species have new genes/traits
if NS does not generate new genes
then
NS cant generate new species

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Post by Dougalbod » Wed Oct 07, 2009 2:58 pm

The logic is entirely refutable.

You don't have to make the bricks yourself in order to build a wall.
Leonardo didn't have to make his own paint (though he may have done) to paint the Mona Lisa
etc...

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robsabba
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Re:

Post by robsabba » Wed Oct 07, 2009 3:22 pm

Dougalbod wrote:The logic is entirely refutable.

You don't have to make the bricks yourself in order to build a wall.
Leonardo didn't have to make his own paint (though he may have done) to paint the Mona Lisa
etc...

Please just ignore gamila. He is a troll-bot.

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Post by Darby » Thu Oct 08, 2009 8:58 pm

To get to the original question, DNA mutates because huge molecules have a decent level of instability. What you will find, however, is that organisms which are well-adapted to very stable parts of the environment (like pelagic sharks or horseshoe crabs) tend to have much better mutation-repair chemistry. For them, mutational variation is non-adaptive.

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Re:

Post by Dougalbod » Thu Oct 08, 2009 9:32 pm

Darby wrote:To get to the original question, DNA mutates because huge molecules have a decent level of instability. What you will find, however, is that organisms which are well-adapted to very stable parts of the environment (like pelagic sharks or horseshoe crabs) tend to have much better mutation-repair chemistry. For them, mutational variation is non-adaptive.


That makes sense. So in a stable environment mutation rates will tend to be lower than in changing environments (because changed DNA is more likely to be repaired). Is their any evidence that mutation rates (after any repairs) increase if organisms are subjected to environental stress?

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Post by MrMistery » Fri Oct 09, 2009 4:04 am

well I don't think DNA repair is ever 100% effective (except for maybe DSB repair which is close to that). Repair pathways miss some stuff, so if you got 100 times as many mutations as normal, it is conceivable that after repairs you are still left with something like 2-3% more mutations as normal, which in turn could increase adaptation
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