Register | Sign In


Understanding through Discussion


EvC Forum active members: 65 (9162 total)
2 online now:
Newest Member: popoi
Post Volume: Total: 915,817 Year: 3,074/9,624 Month: 919/1,588 Week: 102/223 Day: 0/13 Hour: 0/0


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   Role of Mutations
Jaderis
Member (Idle past 3425 days)
Posts: 622
From: NY,NY
Joined: 06-16-2006


Message 1 of 62 (323376)
06-19-2006 4:22 PM


I'm not sure if this should be a new topic or if an existing thread can answer my question, but my question is:
What is the role of neutral mutations in selection?
My first thought upon contemplating this question is that neutral mutations have just as much chance to spread among a group as beneficial ones and then may become beneficial on a grand scale (seeing as how generation upon generaration has been able to pass this on without selective pressure either way) pending some event, or even a non-event, but just the fact that enough of the group now hold this mutation.
For example: The evolution of human speech (I am not a biologist or a linguist and have only a basic understanding of how speech may have evolved, so this may be too wide of an example). If a certain individual(s) had the mutation, either for the development of the vocal box or the area in the brain capable of abstract speech/thought, or both, the mutation would not be immediately beneficial to the group as a whole because only the one individual or even a tiny group (possibly isolated from each other at first) would possess this ability. However, over successive generations (the new mutations being neutral and, therefore, not necessarily selected out) the group of individuals would become larger and the gene would then become beneficial to a larger group and those who did not possess it would then possibly be selected out or remain in stasis or branch off because of the new group occupying the same niche. The mutation(s) remains beneficial to the new group and is, consequently, strongly selected for while it remains beneficial.
AIE: Although I want to address the neutral mutations first, I suppose the same thing could be said about mutations that in previous generations would have been damaging, but eventually came along at a time where they became beneficial.
I guess I am trying to posit that the argument made by some that most mutations are harmful or neutral, and that that somehow negates evolution, could be erroneous because of the possibility of a constantly changing nature of mutations.
If this does go to topic, I suppose it should be in the miscellaneous threads.

Replies to this message:
 Message 3 by Wounded King, posted 06-19-2006 6:30 PM Jaderis has replied
 Message 6 by EZscience, posted 06-19-2006 10:14 PM Jaderis has replied
 Message 19 by Scrutinizer, posted 06-22-2006 7:37 PM Jaderis has replied
 Message 62 by Brad McFall, posted 10-22-2006 1:39 PM Jaderis has not replied

  
AdminPD
Inactive Administrator


Message 2 of 62 (323378)
06-19-2006 4:23 PM


Thread moved here from the Proposed New Topics forum.

  
Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 3 of 62 (323467)
06-19-2006 6:30 PM
Reply to: Message 1 by Jaderis
06-19-2006 4:22 PM


The sort of scenario you describe, where a neutral or even detrimental mutation is rendered beneficial by a change in the environment or population, is termed preadaptation.
Preadaptation is not impossible perhaps but it would require a number of unlikely coincidences to come about. Indeed widespread evidence for preadaptation might suggest some form of ID was in operation.
Your description is slightly hazy so I'm not sure if the fact that the mutation becomes beneficial is supposed to be related to its frequency in the population or not, although for language this seems like a reasonable scenario.
I guess I am trying to posit that the argument made by some that most mutations are harmful or neutral, and that that somehow negates evolution, could be erroneous because of the possibility of a constantly changing nature of mutations.
I'm not sure you need such complicated reasoning to do this, simply the fact that mutations which may be neutral or detrimental in one environment may be beneficial in another should be sufficient, you needn't argue that mutations arising in an environment in whihc they are neutral or detrimental may subsequently become beneficial.
TTFN,
WK

This message is a reply to:
 Message 1 by Jaderis, posted 06-19-2006 4:22 PM Jaderis has replied

Replies to this message:
 Message 4 by Jaderis, posted 06-19-2006 9:20 PM Wounded King has not replied
 Message 5 by ramoss, posted 06-19-2006 9:38 PM Wounded King has not replied
 Message 7 by RAZD, posted 06-20-2006 7:11 AM Wounded King has replied

  
Jaderis
Member (Idle past 3425 days)
Posts: 622
From: NY,NY
Joined: 06-16-2006


Message 4 of 62 (323587)
06-19-2006 9:20 PM
Reply to: Message 3 by Wounded King
06-19-2006 6:30 PM


Preadaptation is not impossible perhaps but it would require a number of unlikely coincidences to come about. Indeed widespread evidence for preadaptation might suggest some form of ID was in operation.
I see what you are saying and that could be the case most of the time. However, in certain other cases, such as the development of speech or other adaptations that would not be immediately beneficial to a whole group, this phenomenon would not also require any other unlikely coincidences. It would only require that eventually the trait would be utilized by a larger group after successive generations acquired the adaptation, not necessarily a change in environment or other selective pressure, and would therefore be perceived as beneficial.
Like I said, speech may not be the best example because I know that many differing biological factors contributed to our specific speech capabilities (controlled breathing, the development of Broca's area, etc), but I don't feel that a new trait existing in a population before it's need is immediately apparent or even utilized suggests ID one whit. I think it actually may help ToE by way of explaining some of the more abstract problems being studied (i.e. emotions, social behavior, the ability to learn).
Your description is slightly hazy so I'm not sure if the fact that the mutation becomes beneficial is supposed to be related to its frequency in the population or not, although for language this seems like a reasonable scenario.
Sorry for the haziness. I had a hard time constructing the question because I was dealing in hypothetical scenarios with limited information and I guess it shows But, yes, that is roughly what I am saying.
I'm not sure you need such complicated reasoning to do this, simply the fact that mutations which may be neutral or detrimental in one environment may be beneficial in another should be sufficient, you needn't argue that mutations arising in an environment in whihc they are neutral or detrimental may subsequently become beneficial.
I agree with that, but only if we are throwing environmental change or differences into the mix. Mutations such as human speech and, arguably, other forms of animal communication do not necessarily depend on being selected for or against in any given environment. I would argue that the specific ways in which the communication ability forms in individual species does develop under selective pressure (i.e. birds' mating calls, submissive postures in many social mammals, etc), but the ability to recognize posturing, speak or otherwise vocalize, in general, does not necessarily have to happen or be passed on to successive generations because of any external pressure. It is perceived as beneficial, but the absence of it (in the whole popuation, not just one individual) isn't always deleterious, either. I hope that makes some sense LOL
I'm still trying to come up with other examples that may help illuminate my questions for you, but right now I am stuck on speech/communication. Does anyone know of any good articles/books on the development of speech that can help me narrow my argument?
Thanks for your input WK
Edited by Jaderis, : To fix quote box

This message is a reply to:
 Message 3 by Wounded King, posted 06-19-2006 6:30 PM Wounded King has not replied

  
ramoss
Member (Idle past 612 days)
Posts: 3228
Joined: 08-11-2004


Message 5 of 62 (323594)
06-19-2006 9:38 PM
Reply to: Message 3 by Wounded King
06-19-2006 6:30 PM


I disagree that 'preadatpation' is evidence of I.D. at all. All it means is that there are literally thousands upon thousands of neutral variations out there, and in an environmental change, there is a reasonable likelyhood that one variation is better adapted to the new environment than another variation.

This message is a reply to:
 Message 3 by Wounded King, posted 06-19-2006 6:30 PM Wounded King has not replied

  
EZscience
Member (Idle past 5154 days)
Posts: 961
From: A wheatfield in Kansas
Joined: 04-14-2005


Message 6 of 62 (323611)
06-19-2006 10:14 PM
Reply to: Message 1 by Jaderis
06-19-2006 4:22 PM


Jaderis writes:
What is the role of neutral mutations in selection?
It is a very important one. It was first pointed out by Crow and Kimura in the early 1970's that not all mutations need be beneficial or detrimental, but many can be neutral. The net effect on a population is the retention of genetic variation simply because selection does not act on it. But that is not to say it never will.
We need to step back and consider that the terms 'beneficial' or 'detrimental' are rather loaded terms and often very much determined by the current circumstances that the organism encounters in its life. And circumstances change. Whether a mutation is beneficial, neutral or detrimental is sometimes very much context-dependent. For example, a gene for insecticide resistance is very beneficial to an insect when it is trying to survive in an agroecosystem with heavy insecticide usage, but the same gene is often disadvantageous (compared to alternative alleles) when the selective pressure of the insecticide is removed. So is the mutation to insecticide resistance beneficial? It depends entirely on where the organism finds itself trying to survive.

This message is a reply to:
 Message 1 by Jaderis, posted 06-19-2006 4:22 PM Jaderis has replied

Replies to this message:
 Message 9 by Jaderis, posted 06-20-2006 8:26 PM EZscience has not replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 7 of 62 (323754)
06-20-2006 7:11 AM
Reply to: Message 3 by Wounded King
06-19-2006 6:30 PM


Preadaptation is not impossible perhaps but it would require a number of unlikely coincidences to come about. Indeed widespread evidence for preadaptation might suggest some form of ID was in operation.
But all natural selection operates on existing mutations, which by your definition are now preadaptations.
I think what Jaderis was getting at was more the diversity latent in the population from accumulated non-lethal mutations.

Join the effort to unravel {AIDSHIV} with Team EvC! (click)

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
 Message 3 by Wounded King, posted 06-19-2006 6:30 PM Wounded King has replied

Replies to this message:
 Message 8 by Wounded King, posted 06-20-2006 8:17 AM RAZD has not replied
 Message 10 by Jaderis, posted 06-20-2006 8:32 PM RAZD has not replied

  
Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 8 of 62 (323784)
06-20-2006 8:17 AM
Reply to: Message 7 by RAZD
06-20-2006 7:11 AM


But all natural selection operates on existing mutations, which by your definition are now preadaptations.
Well obviously natural selection only acts on existing mutations, but it certainly need not act only on mutations whose existence precedes that of the selective pressures which render them beneficial.
I think what Jaderis was getting at was more the diversity latent in the population from accumulated non-lethal mutations.
I was not thinking of preadaptation in terms of a large pool of genetic variation but rather as a sort of micro hopeful monster scenario with some sort of neutral trait, not something like a SNP, was present and maintained in the population until it became beneficial.
I'm also not sure if Jaderis is really focusing on the maintenance of a trait within the population or not, when he says...
Jaderis writes:
I suppose the same thing could be said about mutations that in previous generations would have been damaging, but eventually came along at a time where they became beneficial.
This rather suggests a scenario where particular mutations are reocurring de novo which is a different scenario again.
TTFN,
WK

This message is a reply to:
 Message 7 by RAZD, posted 06-20-2006 7:11 AM RAZD has not replied

Replies to this message:
 Message 11 by Jaderis, posted 06-20-2006 8:56 PM Wounded King has not replied

  
Jaderis
Member (Idle past 3425 days)
Posts: 622
From: NY,NY
Joined: 06-16-2006


Message 9 of 62 (324110)
06-20-2006 8:26 PM
Reply to: Message 6 by EZscience
06-19-2006 10:14 PM


Thank you EZ for the names you mentioned. One of my reasons for posting this question was so that someone might point me in the direction of existing research regarding neutral mutations.
I agree that the terms are loaded and that many creationists/IDers tend to forget that mutations can and do switch sides, so to speak. Many of their arguments are based on some form of "well the majority of mutations are bad" and I want to look up research to support that they don't always remain so and thus increase my own understanding and give me some data to back up my ideas.

This message is a reply to:
 Message 6 by EZscience, posted 06-19-2006 10:14 PM EZscience has not replied

  
Jaderis
Member (Idle past 3425 days)
Posts: 622
From: NY,NY
Joined: 06-16-2006


Message 10 of 62 (324112)
06-20-2006 8:32 PM
Reply to: Message 7 by RAZD
06-20-2006 7:11 AM


I think what Jaderis was getting at was more the diversity latent in the population from accumulated non-lethal mutations.
Yes, that's the first part. The second part would be how certain mutations that in and of themselves do not benefit a population in a physical or survival sense are utilized by the population and become beneficial in a more abstract (for lack of a better term) way.

This message is a reply to:
 Message 7 by RAZD, posted 06-20-2006 7:11 AM RAZD has not replied

  
Jaderis
Member (Idle past 3425 days)
Posts: 622
From: NY,NY
Joined: 06-16-2006


Message 11 of 62 (324116)
06-20-2006 8:56 PM
Reply to: Message 8 by Wounded King
06-20-2006 8:17 AM


I'm also not sure if Jaderis is really focusing on the maintenance of a trait within the population or not, when he says...
She
quote:
Jaderis writes:
I suppose the same thing could be said about mutations that in previous generations would have been damaging, but eventually came along at a time where they became beneficial
This rather suggests a scenario where particular mutations are reocurring de novo which is a different scenario again.
I was really hoping to limit the discussion to neutral mutations at first because I knew this scenario would pop up and I don't see how it applies to my first question. My original idea was that there can be certain mutations that exist without selective pressure because they do not directly affect the survival of the individual or species by themselves, but, when utilized by a larer group once it spreads, becomes apparently beneficial.
I would love to discuss the possibility of mutations appearing de novo with you a little later on, tho, especially how it may apply to the introduction of chemicals into an environemnt (A la the nylonase enzyme and insecticide/antibiotic resistance organisms). Was it the chemicals that prompted the mutation, a reoccuring mutation inherent in the species that had either no function or a deleterious effect prior to the introduction of the chemical, or a truly random mutation occuring at just the right time? Or something else entirely?
I'll let you know when I am ready to discuss that. Probably very soon, methinks.

This message is a reply to:
 Message 8 by Wounded King, posted 06-20-2006 8:17 AM Wounded King has not replied

Replies to this message:
 Message 12 by RAZD, posted 06-20-2006 9:32 PM Jaderis has replied
 Message 13 by EZscience, posted 06-20-2006 10:07 PM Jaderis has replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 12 of 62 (324127)
06-20-2006 9:32 PM
Reply to: Message 11 by Jaderis
06-20-2006 8:56 PM


She
Which is why you use an (albino?) male for your avatar?
msg 10 writes:
The second part would be how certain mutations that in and of themselves do not benefit a population in a physical or survival sense are utilized by the population and become beneficial in a more abstract (for lack of a better term) way.
and
My original idea was that there can be certain mutations that exist without selective pressure because they do not directly affect the survival of the individual or species by themselves, but, when utilized by a larer group once it spreads, becomes apparently beneficial.
As in finding a use for that old broken broomstick that's just lying around. Innovation based on a previous base that would not otherwise be available. Selection could be sexual, say for blond hair ...
I would love to discuss the possibility of mutations appearing de novo with you a little later on, tho, especially how it may apply to the introduction of chemicals into an environemnt ...
And knowing that certain genes are more susceptable to certain pollutants than others, increasing the possiblity of repeated mutations in the same general area of the same type from similar exposures at different times.

Join the effort to unravel {AIDSHIV} with Team EvC! (click)

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
 Message 11 by Jaderis, posted 06-20-2006 8:56 PM Jaderis has replied

Replies to this message:
 Message 15 by Jaderis, posted 06-21-2006 12:03 AM RAZD has not replied

  
EZscience
Member (Idle past 5154 days)
Posts: 961
From: A wheatfield in Kansas
Joined: 04-14-2005


Message 13 of 62 (324135)
06-20-2006 10:07 PM
Reply to: Message 11 by Jaderis
06-20-2006 8:56 PM


Jaderis writes:
My original idea was that there can be certain mutations that exist without selective pressure because they do not directly affect the survival of the individual or species
Firstly, all mutations occur 'without selective pressure' - selection is something exerted after the fact of their expression in phenotypes. But otherwise you are correct so far. Many mutations occur and then persist simply because they have no direct effect on the individual's survival - under present circumstances. However, circumstances may subsequently arise where they do affect survival, either negatively or positively.
Jaderis writes:
Was it the chemicals that prompted the mutation
Some chemicals are mutagenic, but they typically cause random damage. Don't confuse resistance to noxious chemicals as something brought about by those same chemicals, because that's not how it works.
Jaderis writes:
...reoccuring mutation inherent in the species that had either no function or a deleterious effect prior to the introduction of the chemical
Here you are much closer to the truth. Resistance to noxious chemcials is a result of selection by those chemicals on individuals bearing mutations that are otherwise neutral or deleterious in the absence of the chemical. However, the production of the mutation itself has nothing to do with exposure to the chemical.
Jaderis writes:
... a truly random mutation occuring at just the right time
Precisely. Only the mutation at the locus in question would occur every generation with a particular frequency with or without exposure to the chemical. It is only consistent exposure to the chemical that causes it to increase in frequency in the population, so its not as fortuitous as you might seem to imply by saying "at just the right time".
Edited by EZscience, : No reason given.

This message is a reply to:
 Message 11 by Jaderis, posted 06-20-2006 8:56 PM Jaderis has replied

Replies to this message:
 Message 14 by Jaderis, posted 06-20-2006 11:43 PM EZscience has not replied

  
Jaderis
Member (Idle past 3425 days)
Posts: 622
From: NY,NY
Joined: 06-16-2006


Message 14 of 62 (324159)
06-20-2006 11:43 PM
Reply to: Message 13 by EZscience
06-20-2006 10:07 PM


Firstly, all mutations occur 'without selective pressure' - selection is something exerted after the fact of their expression in phenotypes. But otherwise you are correct so far. Many mutations occur and then persist simply because they have no direct effect on the individual's survival - under present circumstances. However, circumstances may subsequently arise where they do affect survival, either negatively or positively.
I realize that they occur without selective pressure and that the selection follows the expression, that's not what I suggested. (BTW, I am not being combative, just pointing out what I meant)
What I meant was that they exist and persist, like you said, outside of any selective pressure and that they subsequently become intrinsic to that population (and, perhaps, perceived as beneficial), but they really have no bearing on the survival of the species. Something like this could be an explanation for why humans (and other animals) have emotions, or better yet, specific emotions or how we expres them. I noticed a thread on altruism...maybe something like that?
Maybe you can point me towards some research on the evolution of emotions, if you know of anything offhand ,so that I can go forward with a little more background?
As for the rest of your post...I absolutely agree that the chemicals are not responsible for the mutation, just the increased expression of the mutation (the second question was the one I would be arguing for, btw, the others were just for kicks). Sorry, that was a bad example and I was just throwing out possible talking points for that bad example. Everyone else, please ignore that part of my post!!!
Edited by Jaderis, : Add "hand" to "offhand"

This message is a reply to:
 Message 13 by EZscience, posted 06-20-2006 10:07 PM EZscience has not replied

Replies to this message:
 Message 16 by kuresu, posted 06-21-2006 5:31 PM Jaderis has replied

  
Jaderis
Member (Idle past 3425 days)
Posts: 622
From: NY,NY
Joined: 06-16-2006


Message 15 of 62 (324162)
06-21-2006 12:03 AM
Reply to: Message 12 by RAZD
06-20-2006 9:32 PM


Which is why you use an (albino?) male for your avatar?
Maybe deep down I really want to be an albino peacock Really, I just like the picture. It is different from all the rest, but still amazingly beautiful and proud.
As in finding a use for that old broken broomstick that's just lying around. Innovation based on a previous base that would not otherwise be available. Selection could be sexual, say for blond hair ...
But it it could also not be. It doesn't have to be...that is the crux of my question.

This message is a reply to:
 Message 12 by RAZD, posted 06-20-2006 9:32 PM RAZD has not replied

  
Newer Topic | Older Topic
Jump to:


Copyright 2001-2023 by EvC Forum, All Rights Reserved

™ Version 4.2
Innovative software from Qwixotic © 2024