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How Does Natural Selection Create Ordered Variation?

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How Does Natural Selection Create Ordered Variation?

Postby Doom » Wed Jan 15, 2014 6:18 am

Ok, so I asked a similar question a while ago here: http://www.biology-online.org/biology-forum/about34598.html

Please read my post carefully and then glance over the rest of the thread, particularly the last post, as that about sums up the issue.

I'll quote wildfunguy here:
The intuition is that natural selection can only block a certain amount of mutation.
But in actuality, natural selection can only let through a certain amount of mutation. Creationists have it backward.


So basically natural selection is a filter. It filters the random mutations, selecting only the best for the particular environment. Simple right?


Now here's my problem:
A. A static filter based on a random input will output a uniform result
Of course natural selection isn't static, the environment will change with time. This brings me to the main problem:
B. A dynamic filter applied to a random input will produce a varied but still relatively uniform result
Reason for my conclusion?
Because the changes in the environment will just as likely negate the effects of the previous beneficial mutation.
As you know, mutations can be beneficial, harmful or neutral. This is based entirely on the environment.
So therefore a species could evolve something beneficial (like beetles on a windy island getting shorter wings, meaning they don't get blown off so easily), then in the very next generation, the environment could change so that's a bad thing, negating the effect of the previous beneficial mutation.

So it'd be sort of like intersecting waves. They are just as likely to negate as to add up.
The law of averages dictates that natural selection can't make any progress then, doesn't it?


That pretty much sums up my position.
If someone can please explain where I'm wrong, I'd really appreciate it :)
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Re: How Does Natural Selection Create Ordered Variation?

Postby Cat » Sat Jan 18, 2014 4:59 pm

Try this:

A dynamic filter applied to a DINAMIC random input.

Doom wrote:So it'd be sort of like intersecting waves. They are just as likely to negate as to add up.
The law of averages dictates that natural selection can't make any progress then, doesn't it?


Think about it this way:

You cannot delete established mutations. If shorter wings are a problem now, only individuals carrying NEW counteracting mutations, say double wings, will survive...
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Postby Doom » Sun Jan 19, 2014 11:15 pm

But if that new mutation doesn't materialize, then the species will die out...
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Postby Doom » Tue Jan 21, 2014 2:07 am

Was I unclear in my first post?
158 views and one reply...

You cannot delete established mutations

Isn't that exactly what Natural Selection is?
Filtering the mutations OUT
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Postby JackBean » Tue Jan 21, 2014 5:03 pm

1) why should dynamic filter result in uniform result? That just doesn't make sense, if you once select for for wings, you'll get short wings, if you select for long wings, you'll select long wings.

2) why do you think that the environment always changes into exact opposites?
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.
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Postby Doom » Tue Jan 21, 2014 11:35 pm

1) why should dynamic filter result in uniform result? That just doesn't make sense, if you once select for for wings, you'll get short wings, if you select for long wings, you'll select long wings.

Here's why
Because the changes in the environment will just as likely negate the effects of the previous beneficial mutation.
As you know, mutations can be beneficial, harmful or neutral. This is based entirely on the environment.
So therefore a species could evolve something beneficial (like beetles on a windy island getting shorter wings, meaning they don't get blown off so easily), then in the very next generation, the environment could change so that's a bad thing, negating the effect of the previous beneficial mutation.


2) why do you think that the environment always changes into exact opposites?

Not exact opposites every generation, but a windy island might easily become not-windy with lots of predators in a 500 year timepan.
Meaning that
Because the survival of the creature is based entirely on the environment, and the changes in the environment are completely random, there should be no gradual up-hill evolutionary climb (mt. improbable). Becuase 'benificial' will just as likely mean going back down the hill as climbing up the hill.


I hope I don't sound like I'm coming across as an attacker of evolution, I'm just looking for answers.
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Postby Tricho » Wed Jan 22, 2014 1:16 am

Hi,
evolution is not about going uphill, onwards or whatever. It's only about what's best at the moment.
So if an environment changes so that only specifically spezialized organisms have a lot of off springs the population will be uniform after a while. But most of the time it's different things that can increase the fitness, not only one. And if factors change most of the time they don't change for all individuals of a species - only for a population. So you get a variety of phenotypes.
And if species can't adapt to occuring changes they will eventually die out, but that may take a few couple of hundreds of thousands of years.
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Postby JackBean » Wed Jan 22, 2014 9:12 am

as Cat wrote, the counter-conditions, even if they were opposite (highly unlikely), will only very rarely lead to removal of exactly the trait which was beneficial before. Rather, some counter-balancing new trait will evolve. And thus you get something new.
http://www.biolib.cz/en/main/

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