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Horizontal gene transfer contradicts neodarwinism?

  1. Jan 30, 2007 #1
    Here a newsstory about horizontal gene transfer:

    Compare with neodarwinism:
    Since gene swapping by organisms causes genetic variation, does this contradict neodarwinism which claims genetic variation is caused by random mutations?
    Last edited: Jan 31, 2007
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  3. Jan 30, 2007 #2

    jim mcnamara

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    HGT had another name 40 years ago. It was a done deal then. It was known that unrelated bacteria species could sometimes acquire traits from each other. You have virus DNA in some of your cells now, as we speak.

    "Random genetic mutation" means random changes to genes and gene expression. Is it limited to mean that the mutation is by base-mess-ups only where the source DNA is from the organism itself? No. Crossing over, incomplete meiotic conjunction (meiotic drive), partial penetrance: all contribute to variation and to variable gene expression.

    We are are all just leaky bags of chemicals - all us living things. Among the chemicals us organisms leak is DNA. It's in human saliva and fingerprints. The smaller the organism the sloppier things get. At the single cell procaryotic level it's close to chaos.

    So I don't see a connection.
    Last edited: Jan 30, 2007
  4. Jan 31, 2007 #3
    I posted the wrong source link in my first post. The story says that the idea was ridiculed 50 years ago, which is perhaps why u say it was a done deal. However, it now seems to be gaining acceptance.

    I know wikipedia can be an unreliable source, but in the article about symbiogenesis it states:

    Also in other sources people have written about HGT as being a new paradigm, or 'a revolution in biology'. Like this one:

  5. Feb 5, 2007 #4


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    Swapping genes doesn't add any diversity to the gene pool, so there must still be a way to generate new genes.
  6. Feb 5, 2007 #5
    Wikipedia is not a reliable source to acquire accurate information. What you are speaking of is the Synthetic Theory of Evolution1. Mutations is not the only source of genetic variation or diversity. There is also recombination and gene flow2. These two is a major part of the increase of genetic variation.

    1 http://anthro.palomar.edu/synthetic/default.htm
    2 http://www.talkorigins.org/faqs/faq-intro-to-biology.html
  7. Feb 6, 2007 #6


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    Your two links contradict each other on recombination: the first says it does not add new alleles and the second says it does.

    Gene flow, though does not create new genes (as said in your link), it just moves existing ones from on species to another. That creates diversity within a species, but doesn't change the total number of genes in the biosphere. Maybe that seems like splitting hairs, but when the biosphere was all bacteria and other single cell organisms, the total number of genes in the biosphere was pretty limited and creating new ones was important.

    In any case, I think the problem with the OP is simply a misreading of the wik article. Hairsplitting over definitions and particulars aside, the article does mention both recombination and gene flow and links separate articles that discuss them in more detail, including discussing horizontal gene transfer. No contradictions to be found.
  8. Feb 6, 2007 #7

    jim mcnamara

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    russ -
    gene flow is usually defined as between individuals of the same species - but individuals in different populations. Not usually between members of different species.

    And. Gene flow can add new genes to a population, if not a species.
  9. Feb 9, 2007 #8
    My question was based on the wiki article of symbiogenesis. The newsarticle about horizontal gene transfer last week (the one in OP)reminded me of it.

    HGT supports margulis theory of symbiogenesis, but if it doesnt contradict neodarwinism then i wondered how her theory of symbiogenesis does.

    There are some parts of neodarwinism that seem to be assaulted by HGT. The nature article (which is no longer available for free) said that the concept of 'species' was no longer valid. And other sources say that the concept of a 'common ancestor' was also challenged by it, and that the tree of life wasnt really a tree anymore but more like a spiderweb.
    Last edited: Feb 9, 2007
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