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Theory of Evolution vs. Mechanisms

  1. Dec 5, 2004 #1
    What is the difference between the Theory of Evolution,
    and the Mechanisms and Processes of Evolution?

    If someone could please help me out, that would be great!
  2. jcsd
  3. Dec 5, 2004 #2


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    The theory of evolution pretty much goes like this. Within any population of living organisms, the resources needed for every organism to survive and reproduce will exceed the actual resources available. Because of this, competition will ensue within each environmental niche so that any individual or group more fit to acquire the resources available will survive and reproduce at a higher rate than individuals and groups that are less fit. This will cause traits that favor survival and reproduction to proliferate. In order for there to be differential rates of reproductive success within a given population, there must be a certain level of genetic diversity. This comes about through various mechanisms such as mutation, genetic recombination, random drift, and others. The crux of the theory is that all life came into existence in this way.

    Aside from the mechanisms of genetic diversity I've listed, there are various mechanisms of selection itself. The most obvious is the natural selection already mentioned, but there is also sexual selection, in which certain traits are selected for not because they make the organism more fit to survive in its environment, but simply because sexual mates choose this trait in a partner at a higher rate than others. There are also events that can cause selection of traits that do not purvey any survival or sexual selective advantage to organisms, such as catastrophic events that result in a genetic bottlenecking of the population in question. For instance, say there is a flood in a certain location and only three squirrels survive. The population they found will then have the traits of those three squirrels, whether or not those traits were advantageous and would have been selected for through other means.

    There are, of course, many more mechanisms (both known and unknown), but I'll not go into all of them. There are many good books available for you to read that can give you a more complete treatement of the subject.
  4. Dec 5, 2004 #3


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    The theory of evolution is theory that tries to explain the diversity of life present in modern day and its origin.

    The mechanism and process of evolution are what is involves and necessary to produce diversity and changing genomes, and to increase or decrease the frequency of certain allelle/gene/genome.

    Mechanism for genome changes include:
    - DNA replication errors
    - DNA damage cause by physical or chemical stress
    - Horizontal gene transfert (HGT) which includes Viruses that integrate their genome inside the host genome, mobile genetic elements such as transposon, acquisition of gene from the environment (in microorganism) and the transfer of genetic material between individuals (in microorganisms i.e. bacterial sex). HGT is porbably the most powerfull and major evolutionary tool for, at least, microorganism and it could explain "quantum leaps" in terms of evolution.
    - Sexual reproduction and chromosome cross-over.
    - Adaptive mutation. Increase of mutation rate when organisms are under stress (this is controversial subject)

    The change in allelle is affected by mechanism of selection and loseyourname gave a good list and explaination.

    - Genetic drift
    -- Small population
    -- Bottleneck effect
    -- Founder effect

    - Natural selection
    -- Negative selection
    -- Directional selection
    -- Balancing selection
    -- Ecological selection (Natural minus sexual)
    -- Sexual selection

    - Artificial selection
  5. Dec 6, 2004 #4


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    In short, the theory explains the diversity of life on Earth, how evolution happens, and what the history of evolution has been. The mechanisms and processes are the "how" part.
  6. Dec 7, 2004 #5

    Thanks everyone!
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