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A Question About Evolution...

  1. Dec 5, 2018 at 12:18 PM #1
    Hi, i just read that a lot of genetic mutations are neutral and do not have much of an effect on the organism or the population.

    But sometimes, when the environment suddenly changes these neutral mutations can become advantageous and can aid the organism in surviving or in reproduction ect..

    I was just wondering if anybody could give me some examples of neutral mutations becoming advantageous after a sudden environmental change.. ?

    Thanks !
     
  2. jcsd
  3. Dec 5, 2018 at 12:28 PM #2

    DaveC426913

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    This doesn't actually fit what you're asking for, but it's a classic example of harmful mutation becoming beneficial.

    Look up malaria and sickle cell anemia.
     
  4. Dec 5, 2018 at 1:37 PM #3

    Klystron

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    Look for a study from the UK about a species of moth that spends most of its adult life clinging to particular trees. The moth populations before the Industrial revolution favoured light colored wings that matched the tree bark; apparently visually shielding the moths from predators. As coal burning became common, tree bark became colored with soot and grime making light colored moths more visible and dark winged moths more protected, less visible to predators and, therefor, favoured to reproduce.

    This study appears in several textbooks but I lack a reference to peer reviewed studies that validate the idea that "evolution" responds so quickly to this environmental change; i.e., persistent soot.

    [Edit: I wrote quotes around the word evolution to indicate I was using the word loosely to represent the functions responsible for biological change. Was not aware of sensitivity of this case study; only its ubiquity. Norm]
     
    Last edited: Dec 5, 2018 at 8:10 PM
  5. Dec 5, 2018 at 4:23 PM #4
    Thanks guys, i will have a read about these topics !
     
  6. Dec 5, 2018 at 5:18 PM #5
    The species in question is the peppered moth (Biston betularia).
    An open-access critique of the debate over its importance as an example of evolution by natural selection is given here.
     
  7. Dec 5, 2018 at 9:04 PM #6

    DaveC426913

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    Caveat: I recall reading something about this turning out to be much less of a big deal than it first seemed. Something about the sampling not being very careful? Like: their number of populations were off because they were only recording ones they spotted - which sort of invalidated the whole study.

    Or something.

    I suspect I'm talkin' through my hat.

    There has been some controversy, although not of the kind in my example.
     
  8. Dec 6, 2018 at 4:47 PM #7

    Klystron

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    If Lepidoptera studies are too controversial an example, consider studies of zebra populations from modern Africa. Zebra coats, not unlike our moths, display complex patterns of light and dark. Previous theories of the selective evolution of the distinctive zebra pattern involved comparisons to natural grasses with a nod toward herd behaviour in the presence of predators. A recent Nova science program claimed data supports hypotheses that zebra stripes create a moire pattern in the predator's vision interfering with the predator striking vulnerable zebra anatomy. Herd "crossing pattern" movements in the presence of predators also make sense if the object is to "confuse the cat".

    Coincidentally, both examples -- moths and zebras -- involve melanism, predator-prey interactions, light/dark patterns and cryptology (in this context of camouflage). In this case the environmental changes could be changes from forest to grasslands, predator-prey distributions, climate, and binocular vision enhancements in large predator species; along with divergence of zebra coat patterns from donkeys and other related species.


    --Norm
     
    Last edited: Dec 6, 2018 at 4:56 PM
  9. Dec 6, 2018 at 6:42 PM #8

    CWatters

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    I'm not quite sure this is what you are looking for but....

    It looks like humans picked up a gene mutation from Denisovans that later became useful when they migrated to higher altitudes in Tibet...

    https://www.sciencemag.org/news/2014/07/tibetans-inherited-high-altitude-gene-ancient-human
     
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