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Thread: Evolution Question

  1. #1 Evolution Question 
    Forum Radioactive Isotope zinjanthropos's Avatar
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    Can someone please explain what this all means? Does it prove diversification is a pre-determined process as the article suggests?


    All that belongs to human understanding, in this deep ignorance and obscurity, is to be skeptical, or at least cautious; and not to admit of any hypothesis, whatsoever; much less, of any which is supported by no appearance of probability...Hume
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    I'd prefer to read the full paper on it, but the short of it is that the bacteria only have a given determined set of conditions and materials to start with.
    DNA chains are quite long and any random change is liable to not be noticed unless the change is severe enough - this is because of redundancies in DNA since systems require other systems to function- For example if you had a mutation pop up that made you grow eyes in the back of your head... it would not get implemented because all of the other structure involved would not be encoded in the DNA.
    The greater the change, the more systems are affected and therefor, the more sections of DNA must be modified to account for that initial change.

    What this leaves is a basic course, due to raw materials available, environment and systems requirements that the bacteria are able to follow. Should a change be too severe, the bacterium that changed heavily would probably just die and those that didn't would continue the culture.

    So, it doesn't "prove" a pre-determined diversification for evolution as a whole.
    It demonstrates that only workable and functional change can be implemented.


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    Forum Radioactive Isotope zinjanthropos's Avatar
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    Quote Originally Posted by Neverfly View Post
    What this leaves is a basic course, due to raw materials available, environment and systems requirements that the bacteria are able to follow. Should a change be too severe, the bacterium that changed heavily would probably just die and those that didn't would continue the culture.

    So, it doesn't "prove" a pre-determined diversification for evolution as a whole.
    It demonstrates that only workable and functional change can be implemented.
    So in the scenario of an unchanging environment, evolution is pre-deterministic? Does this mean that in such a situation the bacteria will continue to change or will it reach a point of evolutionary stagnation?
    All that belongs to human understanding, in this deep ignorance and obscurity, is to be skeptical, or at least cautious; and not to admit of any hypothesis, whatsoever; much less, of any which is supported by no appearance of probability...Hume
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    Quote Originally Posted by zinjanthropos View Post
    So in the scenario of an unchanging environment, evolution is pre-deterministic?
    To a degree, you could say that... But I'd put it that there are higher probabilities of certain developments, is all.
    Quote Originally Posted by zinjanthropos View Post
    Does this mean that in such a situation the bacteria will continue to change or will it reach a point of evolutionary stagnation?
    Who knows? It depends on what mutations occur. That one study is just that one study and it suggests a high probability of repeated paths taken, it does not preclude the element of chance, in spite of what the journalist speculated.
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    WYSIWYG Moderator marnixR's Avatar
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    this paper makes the assumption that because certain genetic pathways tend to repeat themselves (and presumably that includes what type of mutations are likely to have survival value) everything else is deterministic

    the bigger picture obviously has to include the hand of history, where events can be anything but deterministic
    presumably that's why organisms go extinct : their genetic make-up only enables them to deal with so much change and variability, and when that change exceeds their ability to adapt or cope, they go extinct - simples
    "Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
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    I think that the word "deterministic" shouldn't be used, here, actually. It may be deterministic to a degree, but that's very different from the implications the article spun to the word.
    Sadly, my brain is not functioning well enough to come up with a better descriptive...
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    I'd say the biggest clue lies in this extract from the article.

    That's because initially, when everyone is going after the same resource, an individual who can tap into a different resource has a distinct advantage and will be able to produce more descendants.
    The circumstances of the experiment were tightly constrained, but we see the same thing in real life in "parallel" evolution. Different species in various circumstances come up with the same 'solution' to environmental conditions.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
    "nature is like a game of Jenga; you never know which brick you pull out will cause the whole stack to collapse" Lucy Cooke
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    Quote Originally Posted by Neverfly View Post
    I'd prefer to read the full paper on it....

    It's freely available, for those interested:

    Herron MD, Doebeli M (2013)
    Parallel Evolutionary Dynamics of Adaptive Diversification in Escherichia coli.
    PLoS Biol 11(2): e1001490. doi:10.1371/journal.pbio.1001490



    Alternatively, there's a short accompanying "Primer" piece in the same issue that puts the paper into it's proper biological context:

    Marx CJ (2013) ]
    Can You Sequence Ecology? Metagenomics of Adaptive Diversification.
    PLoS Biol 11(2): e1001487. doi:10.1371/journal.pbio.1001487
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  10. #9  
    SHF
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    Quote Originally Posted by Neverfly View Post
    For example if you had a mutation pop up that made you grow eyes in the back of your head... it would not get implemented because all of the other structure involved would not be encoded in the DNA.
    Sure about this? What about experiments putting mouse Pax 6 into flies and developing eyes on various body parts...
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    Quote Originally Posted by SHF View Post
    Quote Originally Posted by Neverfly View Post
    For example if you had a mutation pop up that made you grow eyes in the back of your head... it would not get implemented because all of the other structure involved would not be encoded in the DNA.
    Sure about this? What about experiments putting mouse Pax 6 into flies and developing eyes on various body parts...
    That would be flies, not Humans... and I agree the example is poor. The first one I thought of was a mutation causing you to grow wings... But I ran into the same problem: That would require a series of successive mutations. The difficulty in providing an example is in that you want to come up with something striking that the reader can relate to easily and visualize... but it's really hard to think up a mutation that people would recognize as an obvious change that also would be prevented by a lack of genetic structure to support that mutation from causing physical change.

    A mutation that alters the manufacture of adrenaline, for example, would just kinda leave a lot of people uninspired...
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    Quote Originally Posted by Neverfly View Post
    That would be flies, not Humans...
    Only because it would be unethical to do so in humans.
    I gave the example to question what I interpreted as your suggestion of a principle of a single gene being expressed in a novel location not being able to induce ectopic tissue growth. I was saying this is possible if the gene is a ‘master control’ gene. The pax 6 says ‘grow an eye here’. This wouldn’t need a series of mutations.
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    Universal Mind John Galt's Avatar
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    Quote Originally Posted by Neverfly View Post
    [A mutation that alters the manufacture of adrenaline, for example, would just kinda leave a lot of people uninspired...
    How would you distinguish that from the effects of reading threads in the Trash Can?
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  14. #13  
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    Quote Originally Posted by SHF View Post
    Quote Originally Posted by Neverfly View Post
    That would be flies, not Humans...
    Only because it would be unethical to do so in humans.
    I gave the example to question what I interpreted as your suggestion of a principle of a single gene being expressed in a novel location not being able to induce ectopic tissue growth. I was saying this is possible if the gene is a ‘master control’ gene. The pax 6 says ‘grow an eye here’. This wouldn’t need a series of mutations.
    I'm too ignorant on how pax 6 works to really have a clue as to whether it would cause eye growth anywhere on a humans body. I'll look into it. In the meantime, the majority of mutations are either repaired or go unnoticed, very few result in actual change. Another example you might give would be the effect of thalidomide.
    Quote Originally Posted by John Galt View Post
    How would you distinguish that from the effects of reading threads in the Trash Can?
    One mans trash is another mans treasure.
    I think there are more than a few members that root around in the trash can on here.
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