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Author Topic:   Are mutations truly random or are they guided?
AZPaul3
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Posts: 8513
From: Phoenix
Joined: 11-06-2006
Member Rating: 5.3


(1)
Message 8 of 134 (548582)
02-28-2010 10:34 AM
Reply to: Message 1 by herebedragons
02-27-2010 11:46 PM


Round and Round We Go
I shouldn't be surprised by this OP. Most people just do not do the research to find out if these things have been answered.
The data may be presented in a few dozen forum messages here but it still takes months of research to comprehend.
This is not a new question. In fact it is 300+ years old at this point and a guided or directed mechanism has already been found: Natural Selection. Only the "guiding" is blind to the population and the "directing" is brutal to the individual.
Two points to be addressed:
Randomness of mutation. Before you can assess the random nature of mutation you must first understand the mechanisms of mutation. A small start might be here. Note the randomness studies, google these for additional information, follow the links and learn.
Acquired Characteristics. The directed mechanism you may be looking for is called Acquired Characteristics. Traits acquired by the individual during its life or from the environment around it are passed on to its offspring. For this to occur there, of course, must be some kind of feed-back mechanism into the genome of the individuals germ cells so that these new characteristics are inherited by the offspring.
Start with Jean-Baptiste Lamarck. Do the research and learn how these ideas have been so thoroughly refuted. As you get deep into it you might be surprised at the lack of some overarching "world view" that directed the research. There is no identifiable feedback mechanism from environment to DNA of the individual. The only identified mechanism is Natural Selection which operates its feedback at the level of populations. Now, unless one wants to posit some kind of magic, other-dimensional or divine mechanism this is the totality of the present science.
If you want to see an example of the effects of ignoring the science on this subject then research Trofim Denisovich Lysenko.

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AZPaul3
Member
Posts: 8513
From: Phoenix
Joined: 11-06-2006
Member Rating: 5.3


Message 46 of 134 (548755)
03-01-2010 3:50 PM
Reply to: Message 45 by slevesque
03-01-2010 3:25 PM


Re: Neutral mutations
I think you missed Coyote's point. He was not saying Sickle cell was slightly- or nearly- anything.
The same mutation can be both beneficial and deleterious in the same population at the same time.
The overall effect of the mutation is beneficial to the population in total. That is why it stays around.
Edited by AZPaul3, : explain.

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AZPaul3
Member
Posts: 8513
From: Phoenix
Joined: 11-06-2006
Member Rating: 5.3


Message 52 of 134 (548766)
03-01-2010 4:36 PM
Reply to: Message 42 by slevesque
03-01-2010 3:09 PM


Re: Neutral mutations
And also since the vast majority of mutations are only slightly deleterious, therefore 'undetected' by natural selection won't become beneficial in a changing environment (since the environment is a component of natural selection) and so will stay deleterious.
This also is not correct, slevesque.
A trait (mutation) labeled neutral in the present environment may not be so in a changed environment. The trait may not be subject to strong selection pressures in the present environment but change the environment and the selection pressures change as well.
Environments are always changing, though generally not on a scale less than millennia, and that is why genetic diversity is important to a species survival. As the environment changes those individuals with some neutral or slightly bad traits (as viewed in the old environment) may be better adapted to the new.

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AZPaul3
Member
Posts: 8513
From: Phoenix
Joined: 11-06-2006
Member Rating: 5.3


Message 55 of 134 (548769)
03-01-2010 4:43 PM
Reply to: Message 50 by slevesque
03-01-2010 4:23 PM


Re: Neutral mutations
A person with the one sickle cell gene from one parent is better protected from malaria. Since we inherit copies of genes in pairs, one from mom, one from dad, in those instances where an individual inherits a sickle gene from both the result is devastating to the individual. That results in the sickle cell disease. The remainder of the population with only one copy of the gene receives a benefit.

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AZPaul3
Member
Posts: 8513
From: Phoenix
Joined: 11-06-2006
Member Rating: 5.3


Message 58 of 134 (548774)
03-01-2010 4:54 PM
Reply to: Message 56 by slevesque
03-01-2010 4:45 PM


Re: Neutral mutations
I'm afraid that is not correct. Selection pressures result from the attributes of the environment. Change the environment and you have, by definition, changed its attributes thus its selection pressures.
Don't think of Natural Selection as some monolithic entity separate from the environment. The attributes of the environment, the selection pressures presented by the environment, are Natural Selection. Change the environment, change the selection pressures, change NS.
Edited by AZPaul3, : No reason given.
Edited by AZPaul3, : No reason given.

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AZPaul3
Member
Posts: 8513
From: Phoenix
Joined: 11-06-2006
Member Rating: 5.3


Message 62 of 134 (548779)
03-01-2010 6:52 PM
Reply to: Message 59 by slevesque
03-01-2010 6:36 PM


Re: Neutral mutations
many mutations are so subtle that it doesn't have any noticeable effect on the phenotype.
That you cannot discern the minute difference does not mean it is not there. In another environment it may have a profound effect on survival and reproducibility. I would guess lots of mutations are nothing more that some unique fold in one small corner of a protein. Unnoticed, benign. Until ...
Edited by AZPaul3, : No reason given.

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AZPaul3
Member
Posts: 8513
From: Phoenix
Joined: 11-06-2006
Member Rating: 5.3


Message 63 of 134 (548781)
03-01-2010 7:04 PM
Reply to: Message 59 by slevesque
03-01-2010 6:36 PM


Re: Neutral mutations
A nearly-neutral mutations by it's very definition is one who has no perceivable effect by NS. This includes selective pressures in any environment.
(emphasis mine)
I understand Natural selection.
No, you do not.
Edited by AZPaul3, : No reason given.

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AZPaul3
Member
Posts: 8513
From: Phoenix
Joined: 11-06-2006
Member Rating: 5.3


Message 72 of 134 (548892)
03-02-2010 10:09 AM
Reply to: Message 69 by Taq
03-02-2010 9:41 AM


Re: Neutral mutations
I think it would be a safe bet that most mutations do not affect either gene expression or amino acid sequence in any noticeable way.
I can agree with this.

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AZPaul3
Member
Posts: 8513
From: Phoenix
Joined: 11-06-2006
Member Rating: 5.3


Message 79 of 134 (548923)
03-02-2010 2:04 PM
Reply to: Message 78 by Taq
03-02-2010 1:37 PM


Re: Neutral mutations
I think I understand what you are saying, but, could you please translate this to laymanese for us?

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 Message 78 by Taq, posted 03-02-2010 1:37 PM Taq has replied

Replies to this message:
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AZPaul3
Member
Posts: 8513
From: Phoenix
Joined: 11-06-2006
Member Rating: 5.3


Message 87 of 134 (548958)
03-02-2010 6:58 PM
Reply to: Message 80 by Taq
03-02-2010 2:47 PM


Re: Neutral mutations
Excellent. Thank you, Taq.

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AZPaul3
Member
Posts: 8513
From: Phoenix
Joined: 11-06-2006
Member Rating: 5.3


Message 104 of 134 (549054)
03-03-2010 2:26 PM
Reply to: Message 100 by herebedragons
03-03-2010 11:21 AM


Re: Help! my thread has been hyjacked
Note the bolded word evidence.
Was there something wrong with the randomness studies cited by Taq and myself?
Did you even look at them?
In your view do thses not constitute "evidence?"

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AZPaul3
Member
Posts: 8513
From: Phoenix
Joined: 11-06-2006
Member Rating: 5.3


Message 114 of 134 (549145)
03-04-2010 10:06 AM
Reply to: Message 109 by ZenMonkey
03-04-2010 1:15 AM


Re: unreal expectations based on false information
Bolder-dash writes:
Whoohoo, read a biology book! Good one! Strong reply!
Man you got me good with that one! How long did it take you to think of that devastating rebuttal?
Well, why don't you?
Because his faith is weak and he is afraid reality will crush it. Rather than acknowledge his god's work as he has revealed it to us in this universe the fool must deny his work to hold onto a cherished fantasy.
He has nothing left to fight with in the way of fact or argument so he must rely on denial and bluster.
Unfortunately we cannot expect anything better from such delusion.

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