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Yet another evolution question

  1. Jan 13, 2005 #1
    How does natural selection change the DNA of a population of a certain species to create a new species? In order for a new species to evolve into another wont new DNA have to be formed some how? If so where does this new DNA come from?
  2. jcsd
  3. Jan 13, 2005 #2
    Evolution doesn't require "more" DNA to make a new species, it just requires one species to be different enough from another so that they can't produce viable offspring. This difference can be achieved solely by having different genes, but with the same amount of actual DNA.

    As far as new DNA material, as in longer DNA strands, this could easily come from some sort of mutation, as in an error in the DNA copy process causes extra sequences of genes to be tacked on. But it's important to realize this is not necessary for evolution.
    Last edited: Jan 13, 2005
  4. Jan 13, 2005 #3


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    To add to jake comments, new DNA can be fabricated and gene can be duplicated. Therefore, each gene will specialized and have different function.

    Virus also can transfers genetic material between species.

    For bacterial, genome reduction can also lead to speciation. One of the best example is Yesinia pestis (i.e. plague agent). It has hypothesised that Y. pestis is a species that was created from Yesinia pseudotuberculosis about 20 000 to 5 000 years ago. These two bacteria are pratically similar but one cause digestive track infection (Y. pseudotuberculosis) and the other cause respiratory and septicimia and is transmitted by fleas. Both genome have been compare and Y. pestis appears to have less functional genes.
    Last edited: Jan 13, 2005
  5. Jan 13, 2005 #4


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    I make no claim that this is an important phenomenon in speciation, but some viruses are able to get new material (new from the point of view of the host's genome) inserted into the host's DNA, if I remember correctly.
  6. Jan 15, 2005 #5
    I may be reading your question wrong. But, it does not sound like you have a grasp on evolution.

    Natural selection only selections on mutations within the DNA. So the "new" DNA is already made by mistake and if it is a benefit it is then selected upon by nature. Eventually, this can lead to a significant different so that the new species can no longer breed with the original species.

    You asked how the new DNA is made. Like I mentioned, purely by mistake. Mistakes are made while copying the old DNA.

    And, yes. This is a very simplyfied vesion of events.

  7. Jan 17, 2005 #6


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    Welcome to Physics Forums, Video

    First, DNA is comprised of many, many genes. The genes are what give species/individuals their traits. During speciation (formation of new species), whole DNA strands are not created...instead, some fraction of the existing DNA strand (some number of its genes) is changed. How many genes? No specific number...just whatever is enough to separate the species into distinct groups that don't/can't inter-breed anymore.

    Second, some mechanisms of evolution increase genetic variability (make new or different genes in the DNA strand) and some mechanisms decrease variability.

    Natural selection decreases variability. You may have heard of the catch-phrase "survival of the fittest". Over the whole range of variations within a species (e.g., tall/short, fast/slow, etc.), natural selection tends to favor beneficial traits (genes) and eliminate the traits (genes) that are not as good. It's not making new genes, but instead it's favoring the propogation of certain genes. Which ones? Whichever work the best in whatever ecological situation the species is in.

    New information (genes) can come from things like:
    - mutation - These are often DNA copying errors which can do things like rearrange, duplicate, flip, or modify genes. Note that these changes can be considered "new" genes because they are different than they used to be. But big changes in an organism can also come from the changes in the interactions of genes (not just new genes).
    - recombination - reshuffling of genes during sexual reproduction
    - gene flow - influx of new genes into a population from another similar population that was previously separated
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