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Author Topic:   Please explain mutations
Jonathan
Inactive Member


Message 1 of 10 (20759)
10-24-2002 11:57 PM


Since the TOE relies on the use of multiple mutations to account for the gradual progressive changes made in an organism, please explain how this process works. I hear it referred to constantly and its process is never questioned or explained. How are the traits inherited? Is the DNA changed at birth or after? Are they always passed on? Can they ever breed out nullifing the change? etc. Since this occurs so easily in nature then it must have been studied at length in the lab. What were the results? Where can I find out more about them?
Replies to this message:
 Message 2 by Tranquility Base, posted 10-25-2002 1:59 AM Jonathan has not yet responded
 Message 3 by Quetzal, posted 10-25-2002 2:47 AM Jonathan has not yet responded
 Message 10 by Brad McFall, posted 11-13-2002 11:54 AM Jonathan has not yet responded

  
Tranquility Base
Inactive Member


Message 2 of 10 (20764)
10-25-2002 1:59 AM
Reply to: Message 1 by Jonathan
10-24-2002 11:57 PM


^ I don't have much time Jonathon but here's a few quick points.

Mutations happen in DNA (ie genes) in all cells, at all times, including 'germ-line' cells (sperm/egg) which will pass these new traits on. At some level mutations are purely random, at another level they are somewhat non-random in two-ways: (i) some DNA errors are less likely to be picked up by repair machinery and (ii) selection due to differential survivability will choose the good mutations to preferentialy survive.

In practise almost all results in the lab, or known results in nature, produce modified versions of existing genes that are either inactive or still have the same biochemical funciton just with a stronger or weaker 'binding strength'. SO as an explanation for the evolution of the nanomachines in our cells mutaitons is a 'well it wouldn't defy the laws of physics' sort of answer.

PS: the most fascinating example of a mutaiton I ever heard of was of a patient who was being treated for a genetic disease (a near-essential gene was inactivated by a mutaiton sometime in the past generations). Nothing worked and then suddenly the patient started getting better. it turned out that the histoircal mutation back flipped by chance in the important tissues and the patient recovered. If anyone knows the details let me know - I've forgotten. ON the molecular levle the patient had a dud 'gizmo' (eg: an enzyme) - almost perfect but it had a flaw. Random chance flipped that flaw back right again and then the whole gizmo started working again.

[This message has been edited by Tranquility Base, 10-25-2002]


This message is a reply to:
 Message 1 by Jonathan, posted 10-24-2002 11:57 PM Jonathan has not yet responded

  
Quetzal
Member (Idle past 4036 days)
Posts: 3228
Joined: 01-09-2002


Message 3 of 10 (20766)
10-25-2002 2:47 AM
Reply to: Message 1 by Jonathan
10-24-2002 11:57 PM


Hi Jonathan,

TB gave a very good precis of what is meant by "mutation". I'll just add a few details on how they fit within evolutionary theory.

Speciation (and in fact evolution in general) is a two-step process. In the first step, variation arises in a population. Variation = some traits or characteristics of an individual organism that reflect a difference between it and all other organisms of the same type within a local population. There are basically two ways (simplifying the thing) as to HOW this variability comes about:

1. genetic recombination that occurs during gametogenesis (the formation of egg/sperm - meiosis) through crossing over, randomization during the anaphase of meiosis I, and random selection of gametes during fertilization (there's no way to predict which egg is fertilized by which one of millions of sperm).

2. mutation, which in its essence is simply an error that arises during some portion of the DNA copying process, etc. As TB noted, most errors are fixed when they occur. Some aren't, hence mutation. These unfixed errors are the source of novel genetic material. If they occur in a sperm/egg, then the mutation is inherited.

These two processes are the direct ways variation arises in a population. Another, indirect process, is called genetic drift, and is a random statistical process by which the frequency of a particular trait or suite of traits can change within a small population simply through the vagaries and vicissitudes of life. For the purposes of simplifying as far as possible this discussion, I will only consider the first two direct sources of variation.

First off, we need to clarify the relationship between these two sources of variation. Mutation creates the novel genetic material – the multiple alleles affecting a given characteristic – within the population’s gene pool. Major mutations are generally eliminated immediately because their deleterious effects preclude them being passed on. (I’m excluding gene doubling – polyploidy - in plants here, since that’s something of a special case.) Most of the non-lethal mutations are essentially neutral in a particular environment simply because they have no immediate effect on the organism’s development or survival. After all, there’s a second copy of a fully functioning gene around to take up the slack (avoiding dominance and polymorphism questions for simplicity). In this instance “normal” recombination during meiosis can throw up homozygous versions of the new genes. BTW: Crossing over is able to (rarely) produce novel sequences all on its own. But novel genetic material is primarily created through mutation. Recombination and the randomizing process of meiosis MAY permit the expression of the novel material. Otherwise it just sort of hitch-hikes its way down the generations, or may possibly be eliminated from the population by chance alone. In addition, polymorphisms can be created when the recessive has an net effect even though recessive (think sickle cell anemia).

The next step in the process is natural selection. Environmental factors (known collectively as “selection pressures”) act on those varied characteristics that have some impact on the organism’s individual survival. (“environment” in this context = “all biotic and abiotic factors that have an influence on the organism in it’s particular ecosystem”. These factors include both non-living elements such as terrain, climate, rainfall, etc, and living elements such as other species, food resources, and even members of the organism’s own population). These selection pressures in the organism’s environment tend to favor the survival of individuals with certain characteristics, primarily by weeding out those individuals who DON’T have those characteristics. Over evolutionary timescales, these gradual changes in individual populations can create genuinely new species (there are a number of ways to shortcut the process, but that's the gist.)

Hope this answers your question.


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 Message 1 by Jonathan, posted 10-24-2002 11:57 PM Jonathan has not yet responded

  
Jonathan
Inactive Member


Message 4 of 10 (20787)
10-25-2002 11:20 AM


OK. That explains the functions of the mutation process. Now can someone provide a hypothetical mathamatical model for the mutations to occur in. For example. How many mutations and how much time will it take for a singe celled organism to mutate into a house fly? If it takes 1 year for a single mutation to occur in a species and 1 in every 500 mutations are beneficial then it would take 500 years for one beneficial mutation and so on. (These are purely hypothetical numbers that have absolutely no scientific basis.) Roughly how many mutations will be needed for the transformation? I realize that there is no definate answer to this question, I just want a rough idea.

Thanks.


Replies to this message:
 Message 6 by nos482, posted 10-25-2002 11:59 AM Jonathan has not yet responded

  
Karl
Inactive Member


Message 5 of 10 (20792)
10-25-2002 11:35 AM


Jonathan - a single celled organism will never mutate into a housefly, because individual organisms do not evolve - populations do.

There's more to your misunderstanding. There is not a single father-son lineage of organisms in a population, so it's not a simple case of say 1 mutation per generation, 1 favourable per x generations. There are many organisms per generation (and of course reproduction within the population is not organised into discrete generation events). So figures are rather hard to generate. How big's the population? What is the mutation rate per million base pairs? How good is the error prevention mechanism? How big is the genome? What proportion of it is functional?

And so on.

Evolutionary change rates are measured in Darwins, and a very accessible article on research into the subject is to be found here: http://www.calacademy.org/calwild/fall97/html/horizon.htm


Replies to this message:
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nos482
Inactive Member


Message 6 of 10 (20798)
10-25-2002 11:59 AM
Reply to: Message 4 by Jonathan
10-25-2002 11:20 AM


quote:
Originally posted by Jonathan:
OK. That explains the functions of the mutation process. Now can someone provide a hypothetical mathamatical model for the mutations to occur in. For example. How many mutations and how much time will it take for a singe celled organism to mutate into a house fly? If it takes 1 year for a single mutation to occur in a species and 1 in every 500 mutations are beneficial then it would take 500 years for one beneficial mutation and so on. (These are purely hypothetical numbers that have absolutely no scientific basis.) Roughly how many mutations will be needed for the transformation? I realize that there is no definate answer to this question, I just want a rough idea.

Thanks.


Evolution doesn't work that way. You are basically putting effect before cause as if what an organism will eventually be is pre-determined. If evolution had to start all over again we may get completely different forms of life than we do now. In other words what best helps an organism survive to pass along a said trait to the next generation is what is used. Evolution is also a very wasteful "process".

BTW, have you seen any of those high level artificial life programs? Some of the forms they produce using the evolutionary process are quite weird in comparison to what we're use to, but they do function well in their environment.

[This message has been edited by nos482, 10-25-2002]


This message is a reply to:
 Message 4 by Jonathan, posted 10-25-2002 11:20 AM Jonathan has not yet responded

  
Jonathan
Inactive Member


Message 7 of 10 (20829)
10-25-2002 7:57 PM
Reply to: Message 5 by Karl
10-25-2002 11:35 AM


quote:
Originally posted by Karl:
Jonathan - a single celled organism will never mutate into a housefly, because individual organisms do not evolve - populations do.


Maybe I should have been more clear. For a population that would have been present early on in the stages of life what would a typical evolutionary process be? At what rate would a "population" of flys ,or anything else, evolve? How often did the mutations occur? (over time and per species)

What Im getting at is how do we know what occured and how it worked if no one was there to see it. Just because it "fits" isant good enough. Where is the evidence for it? How can we base a theory on the function of mutations when we dont even know how often the mutations occured? Or for that matter how often a positive mutation occured?


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nos482
Inactive Member


Message 8 of 10 (20848)
10-25-2002 8:52 PM
Reply to: Message 7 by Jonathan
10-25-2002 7:57 PM


Originally posted by Jonathan:

Maybe I should have been more clear. For a population that would have been present early on in the stages of life what would a typical evolutionary process be? At what rate would a "population" of flys ,or anything else, evolve? How often did the mutations occur? (over time and per species)

What Im getting at is how do we know what occured and how it worked if no one was there to see it. Just because it "fits" isant good enough. Where is the evidence for it? How can we base a theory on the function of mutations when we dont even know how often the mutations occured? Or for that matter how often a positive mutation occured?

It all depends in evironmental pressures. Some organism basicially remain the same for millions of years or more. I.E. Sharks and roaches.

And yes, there was "someone" there, the organisms themselves when they speak to us through the fossil record. You are trying to see something which isn't there. The vast majority of mutations are fatal. Evolution is a very wasteful process.


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 Message 7 by Jonathan, posted 10-25-2002 7:57 PM Jonathan has not yet responded

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 Message 9 by gene90, posted 10-25-2002 11:22 PM nos482 has not yet responded

  
gene90
Member (Idle past 1987 days)
Posts: 1610
Joined: 12-25-2000


Message 9 of 10 (20861)
10-25-2002 11:22 PM
Reply to: Message 8 by nos482
10-25-2002 8:52 PM


[QUOTE][B]The vast majority of mutations are fatal.[/QUOTE]

[/B]

That contradicts my understanding, that most mutations are neutral.

Care to debate that point?


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Brad McFall
Member (Idle past 3197 days)
Posts: 3428
From: Ithaca,NY, USA
Joined: 12-20-2001


Message 10 of 10 (22493)
11-13-2002 11:54 AM
Reply to: Message 1 by Jonathan
10-24-2002 11:57 PM


[QUOTE]Originally posted by Jonathan:
[B]Since the TOE relies on the use of multiple mutations to account for the gradual progressive changes made in an organism, please explain how this process works.
[/QUOTE]

[/B]De Vries BEFORE using standard "Mendelian" practice uttered *not* dominance and recessive but active and latent which to my "philosophy" tends to have me think that for the $time$ being discused IN THE EXPERIMENT (F1-F2--and beyond)(not Nature but the Science would lend a narrative at least towards such by inference if not already induced etc)Mendel was inscripting his experimental philosophy by FORM whereas De Vries doing the same science was doing it by SPACE. I was trying to express similary but within the TIME that physics has given science a nature of which (at least Wolfram believes this) where there is SOME reversing of space and time. Croizat takes the talk about to FORM-making & translation in Space as a topic in the subjective taxonomist view at least.

By trying to generalize the ADDITION that De Vries attempted to do with Mendel's work that Mayr seems not to have been able to outthink (maybe because he was stuck on the "gut" of Haeckel which seems to dissaper in the "phylogeny" of Echinoderms if one recoginzes that cucumbers have blood vessels among the 5-fold syymetery that others in the group do not ...)to a 3:1 ratio history reading and writing etc I hit on (by trying to come up with a standard NATURAL SELECTION in Wolfram's deviant position with regard to some taxoGENIC optimization (whehter by directed mutations as per this thread or Grehan's notion of Croizat's "orthogeneis" for instance (AIG thinks this is a "symptom" and Grehan's Taxocom postings more in favor than others of US cretationism as afflicted by the same evolutionary community as panbiogeographers like homosexuality ... may come out this as well AS TO BECAUSE cause etc. and thus IS ALSO IN GENESIS... BIBLE.)))in particular with some of this thought from Stephen Wolfram [A x (non-universality approaching group theory)Aa x a] of Mendel's indpendence of A/a from a/A in A + A/a +a is due to sperm and pollen being small(not because these are males! on chromosome part of heritbility) not being able to express a principia zoologica equal to principia botanica thus finding a commonality that started some vicatiance biogeography and panbiogeography ON LARGE TIME SCALES. I only attempt to USE the same insight but not predict the TIME until AFTER I have sorted out the FORMS of the offspring that already "sprung" from De'Vries'' mutations which WILL matter if they are directed or not.

[QUOTE][B]
I hear it referred to constantly and its process is never questioned or explained.[/QUOTE]

[/B]
Simply denials of creationsim in this case are not able to mustard the custurd or to put the peanut butter and jelly together. What is called for is co-operation of both sides not use of insitutions to assert who ever has the least chemicals added to their bodies wins. This should not sound like a "drug" economics. But it does. Probably becasue people are afraid to think these thoughts for being prematurely (innocently) accused of sexism when it is geographic distributions that were seen
How are the traits inherited?I am not saying that "directed" mutations isnt as per above to start to try to talk equally to all...(one simply can taketalk a standard position with regard to orthogenisis. I certainly do not know know absloutely either way PER orthoselections which would be in my opninion the material database category to look for or have placed the "evidence" (data collection mechnism with values) in....
The interesting thing to note is that Just by attending to the words in the discourse one may gain some insight.

quote:

Is the DNA changed at birth or after?

i DONT KNOW


This message is a reply to:
 Message 1 by Jonathan, posted 10-24-2002 11:57 PM Jonathan has not yet responded

    
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