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Thread: genetic drift vs. natural selection

  1. #1 genetic drift vs. natural selection 
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    My philosophy of science teacher said there is a debate between evolutionists of whether evolution happens through genetic drift or natural selection.

    Why can't they accept that both happen? I don't get where the conflict comes from. Can anybody explain?


    Whence comes this logic: no evidence = false?

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  3. #2 Re: genetic drift vs. natural selection 
    Forum Cosmic Wizard paralith's Avatar
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    Quote Originally Posted by scientstphilosophertheist
    My philosophy of science teacher said there is a debate between evolutionists of whether evolution happens through genetic drift or natural selection.

    Why can't they accept that both happen? I don't get where the conflict comes from. Can anybody explain?
    I dunno what your teacher is talking about. I accept both just fine. The debate probably lies in which one is more common or more important when it comes to shaping species, but you really need a degree of both for evolution to happen. Genetic drift and mutations create variety in the population's gene pool, and natural selection culls that variety to only the traits that are successful in the environment. *shrugs*


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    I seem to recall this debate revolving around the idea of punctuated equilibrium, as though one or the other process is more important for rapid radiation.

    Does that sound familiar to anything your instructor said, scientstphilosophertheist?
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    Quote Originally Posted by free radical
    I seem to recall this debate revolving around the idea of punctuated equilibrium, as though one or the other process is more important for rapid radiation.

    Does that sound familiar to anything your instructor said, scientstphilosophertheist?
    No, he said he won't go into detail.
    Whence comes this logic: no evidence = false?

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  6. #5 Re: genetic drift vs. natural selection 
    Forum Cosmic Wizard spuriousmonkey's Avatar
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    Quote Originally Posted by scientstphilosophertheist
    My philosophy of science teacher said there is a debate between evolutionists of whether evolution happens through genetic drift or natural selection.

    Why can't they accept that both happen? I don't get where the conflict comes from. Can anybody explain?
    I don't think that there is a conflict. In science there are always multiple theories being launched and the proponents always try to push theirs as the most important. The rest of the community follows the debates with great interest because there is nothing better than a flame war in science, with the knowledge that in the end both are probably right, although not often in the same degree.

    Genetic drift and natural selection are both important in evolution. Especially if you define evolution as the genetic change in time. Genetic drift is responsible for some of this change, natural selection for the other.

    They are exclusive.
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  7. #6  
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    Natural Selection accounts for almost all adaptive evolution. Genetic Drift, by its very nature, is simply the random change in allelic frequencies within a population. The two process may complement one another.

    If a population experiences significant survival pressures (depending on factors such as the supply of resources, abundance of predators and prey, etc.), then any genetic change which makes an organism better, or less well, suited to its environment is subject to natural selection, and cannot increase or decrease in frequency by chance.

    If selection pressures are not great, then minor alterations which minimally affect how well an organism is suited to its environment may 'slip through the net' for a period, so to speak, and not be subject to a great deal of selection pressure. However, JBS Haldane, one of the 'founding fathers' of the Modern Synthesis, showed that a selection pressure of just 1/1000 would take a geologically relatively short period to time to push a rare mutation to fixation.

    It must be remembered, that, over time, a species can only become better suited to the environment which they inhabit by means of Natural Selection, probably with some genetic drift acting also, and, indeed, supplementing its effects.
    Knowledge of evolution may not be strictly useful in everyday commerce. You can live some sort of life and die without ever hearing the name of Darwin. But if, before you die, you want to understand why you lived in the first place, Darwinism is the one subject that you must study.

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