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Thread: Convergent Evolution

  1. #1 Convergent Evolution 
    Forum Masters Degree Golkarian's Avatar
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    This is related to something I dismissed in my sialic acid thread.

    Do you think biochemical phenomena can convergently evolve? I'm skeptical because it seems that many different proteins can do similar tasks, so how could the exact or nearly exact protein sequences evolve twice? Doesn't this seem to improbable?


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  3. #2 Re: Convergent Evolution 
    Moderator Moderator TheBiologista's Avatar
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    Quote Originally Posted by Golkarian
    This is related to something I dismissed in my sialic acid thread.

    Do you think biochemical phenomena can convergently evolve? I'm skeptical because it seems that many different proteins can do similar tasks, so how could the exact or nearly exact protein sequences evolve twice? Doesn't this seem to improbable?
    It is improbable, though that's a function of the length of the sequence. But I've never actually heard of convergence working on the molecular level in any significant way. Do you have some specific examples? Typically when we talk about convergence it's to do with morphology.


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  4. #3 Re: Convergent Evolution 
    Forum Masters Degree Golkarian's Avatar
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    Quote Originally Posted by TheBiologista
    Quote Originally Posted by Golkarian
    This is related to something I dismissed in my sialic acid thread.

    Do you think biochemical phenomena can convergently evolve? I'm skeptical because it seems that many different proteins can do similar tasks, so how could the exact or nearly exact protein sequences evolve twice? Doesn't this seem to improbable?
    It is improbable, though that's a function of the length of the sequence. But I've never actually heard of convergence working on the molecular level in any significant way. Do you have some specific examples? Typically when we talk about convergence it's to do with morphology.
    My question is more theoretical, I'm asking if I do come across two very close matches if I should assume a common ancestor.
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  5. #4  
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    My question is more theoretical, I'm asking if I do come across two very close matches if I should assume a common ancestor.
    If the protein is anything but very simple, that's reasonable - but you might have to be careful with determining what you meant by ancestor.

    In cases of symbiosis, viral gene transfer, that kind of thing, the common ancestor of two versions of a protein and the common ancestor of the two organisms it is in might be very different beings.
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  6. #5 Re: Convergent Evolution 
    Forum Cosmic Wizard paralith's Avatar
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    Quote Originally Posted by Golkarian
    Quote Originally Posted by TheBiologista
    Quote Originally Posted by Golkarian
    This is related to something I dismissed in my sialic acid thread.

    Do you think biochemical phenomena can convergently evolve? I'm skeptical because it seems that many different proteins can do similar tasks, so how could the exact or nearly exact protein sequences evolve twice? Doesn't this seem to improbable?
    It is improbable, though that's a function of the length of the sequence. But I've never actually heard of convergence working on the molecular level in any significant way. Do you have some specific examples? Typically when we talk about convergence it's to do with morphology.
    My question is more theoretical, I'm asking if I do come across two very close matches if I should assume a common ancestor.
    Golkarian, no hypothesis of ancestry should be considered confirmed by looking at just one trait. However, if this trait you're looking at is found in two organisms that share many other traits in common as well, then it is more likely that this common molecule is a result of common ancestry. But I say again, looking at that one trait in isolation won't tell you much about its evolutionary history.
    Man can will nothing unless he has first understood that he must count on no one but himself; that he is alone, abandoned on earth in the midst of his infinite responsibilities, without help, with no other aim than the one he sets himself, with no other destiny than the one he forges for himself on this earth.
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  7. #6 Re: Convergent Evolution 
    Forum Freshman electricant's Avatar
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    Quote Originally Posted by Golkarian
    My question is more theoretical, I'm asking if I do come across two very close matches if I should assume a common ancestor.
    If the two proteins have a high degree of sequence homology it is generally accepted that they will share a common origin. The gene sequences could give you a better indication of this.

    It's astronomically unlikely that two proteins would evolve from different starting points to achieve the same structure. However, there are a number of examples of proteins with very different structures that catalyse the same biochemical reaction in different species. This is generally what we mean when we talk about convergent evolution at the molecular level.
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