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Are better-adapted genes less easily mutated?

  1. Aug 13, 2004 #1
    Once a trait is established to its environment, might that indicate, by definition or process, that it is more likely resistant to further changes in that environment?
     
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  3. Aug 13, 2004 #2
    I don't know if this is true or not but if a better adapted gene is resistant to mutation, that would make it a badly adapted gene when new changes come along and it can't mutate.
     
  4. Aug 13, 2004 #3

    NateTG

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    Can you specify what you mean by 'it' in the second clause? Do you mean changes in the environment, or changes in the trait? (Perhaps you can give an example.)
     
  5. Aug 13, 2004 #4

    iansmith

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    The "adapted genes" still mutated and the same rate as the other genes; however, the mutated "adapted genes" may be selected out of the gene pool if it creates a disavantage for the carrier. Mutation occurs in functionnaly important and unimportant regions of a protein. The mutations in functionnaly important usually alter the function and the phenotype. Mutations in functionnal unimportant region usually do not cause a change in phenotype and function of a protein. This also dependents on the type of mutation.

    http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/M/Mutations.html
     
  6. Aug 13, 2004 #5
    iansmith, NateTG and Crumbles - let me modify my original question by asking whether a vital variation among "typical" genes is around their mean likelihood to mutate (saying that a gene in general is more or less beneficially susceptible to radiation or chemicals).
     
  7. Aug 13, 2004 #6

    selfAdjoint

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    It is a fact that some genes are "conserved" across a startlingly large range of species, implying a vast stretch of time. For example I have read we share something like 20% of our genes with some plants (oak trees were mentioned). This implies that some genes are so important that evolution has found a way to shield them from the more common mutations.
     
  8. Aug 13, 2004 #7
    It's strange no one mentioned genetic homeostasis. I think natural selection would tend to favour phenotypes which are more or less the average among the population rather than the extremes. In fact, Gould and Eldredge did use such an argument to make their case for PE, saying that genetic homeostasis acts as a bar against species undergoing anagenesis.
     
  9. Aug 13, 2004 #8

    iansmith

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    There is not a additional protection for certain genes. Some genes are highly conserved because any mutation usually has a negative effects and selected against. These genes were present in the animal and plant common ancestor and were kept due to the importance. These genes are usually an absolute requirement for growth and regulation and any slight modification of the protein protein will result into the death of the cell.

    The mutation rate is similar for any gene with exception of mutation hot-spot; however the substitution rate is low in highly important gene and high in non-coding sequences. It implies that natural selection removes mutation that leads to a decrease in survival.

    However, there is some DNA sequnces that facilitate recombination of DNA and increase recombination repair in a certain area. Those sequnces are found thorugh out the genome and have not yet been show to be specifically associated with important genes. Also the recombination repair mechanism is not perfect and could introduce mutation in the gene.
     
  10. Aug 13, 2004 #9

    iansmith

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    Most of the cellular protection against mutagenic agent are to product the cell and all the genome rather than some specific set of genes. Mutation will be fixed regadless of the type of DNA sequence. Some nucleotides are also more susceptible to certain type of mutation. The relative % of GC of may prevent certain mutation and offer a protective effect but the %GC through out the genome is usually same for any genes/DNA sequences of a given species. %GC is usually different in DNA sequences obtain from other species.

    Deinococcus radiodurans is the bacteria that withstand the most DNA damage but it is due to repair mechanism rather than a "Shield".
     
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