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Thread: Question about evoluton

  1. #1 Question about evoluton 
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    New to evolution and had a question:

    if genetic mutation drives evolution, and i know dinosaus or some of them evolved into birds.

    but if one animal is born with a mutation for the new species to develop there needs to be many. What are the odds many animals would have the mutation and become the same species of bird.

    just an example hopefully somebody understands what im asking


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  3. #2  
    Forum Cosmic Wizard i_feel_tiredsleepy's Avatar
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    This is a common misunderstanding of how evolution functions.

    It's not as if one mutation happens and out pops a bird from a dinosaur egg. It takes many generations of gradual change over several years.


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    WYSIWYG Moderator marnixR's Avatar
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    remember that when you consider a species you always will have to see them as a population of interbreeding individuals - the development of a new trait doesn't make one individual into a new species since it still can interbreed with the rest of the group

    what really makes a new species is when novel traits have become fixed in a population to the extent that it no longer can or does interbreed with other, similar populations
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    either i'm misunderstanding the question or the previous posts have not answered it. you appear to be asking how multiple members of a species can exist when only one recieves a particular mutation.

    the answer to this question requires you to understand quite a few things about evolution and as i do not know the degree of your education on the subject i will explain most of them. as mentioned earlier, it is not just one mutation in one individual that creates a new species, the species must be reproductively isolated from other species. this is the term for the state of being inable to breed that manixR described.

    many traits differ between one species and another, some look alike and some are so different that it is a wonder they share a common ancestor. the reason for this is that in the presence of reproductive isolation, one population can gain certain traits or lose certain traits while another population's amount of said traits remains the same. without reproductive isolation if an increase in a trait occured in a subgroup of the population, other subgroups would be affected in later generations due to interbreeding.

    for instance, millions of years ago humans seperated by a thousand miles or so were reproductively isolated. as a result, humans in africa were able to have the trait of black skin to cope with the exposure to sunlight there, while humans a thousand miles north had white skin. currently the degree of isolation between these areas is lessening with our increase in technology and it is not beyond imagination that this barrier will be all but eliminated in the future. if this occurs then we will observe that in both of these areas the average skin tone will tend to equalize between them.

    the first part of the example showed divergent evolution that over time could lead to speciation. however because in humans it did not lead to speciation it is possible to remove the reproductive isolation barrier and convergence of traits will follow.
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    Universal Mind John Galt's Avatar
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    Quote Originally Posted by saul
    either i'm misunderstanding the question or the previous posts have not answered it. .
    The third possibility is that you didn't understand the two answers.
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    Forum Cosmic Wizard i_feel_tiredsleepy's Avatar
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    To be fair Saul put far more effort into his answer, more than I was willing to do.
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    Universal Mind John Galt's Avatar
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    Quote Originally Posted by i_feel_tiredsleepy
    To be fair Saul put far more effort into his answer, more than I was willing to do.
    I agree that his answer was more detailed, but in essence there was nothing that was not covered by the replies from yourself and marnix in combination. Had he said that your responses might benefit from some expansion, for greater clarity, I would have had no objection. However, as written, he is asserting that you had missed the point. You hadn't.
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    So the SAME mutation must occur MULTIPLE TIMES SPONTANEOUSLY in an "isolated" population, presumably so that the mutants can find each other and reproduce, AND confer enough of an advantage so that the "fittest" survive(as if they don't always, that is what makes them fit, innit?) to pass along these genes.

    Where do dominant/recessive Mendelian genes enter into all this then, because only a certain percentage of offspring express it, depending?
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    Forum Cosmic Wizard i_feel_tiredsleepy's Avatar
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    Quote Originally Posted by The Finger Prince
    So the SAME mutation must occur MULTIPLE TIMES SPONTANEOUSLY in an "isolated" population, presumably so that the mutants can find each other and reproduce, AND confer enough of an advantage so that the "fittest" survive(as if they don't always, that is what makes them fit, innit?) to pass along these genes.

    Where do dominant/recessive Mendelian genes enter into all this then, because only a certain percentage of offspring express it, depending?
    No, a mutation occurs and it is spread in the population in subsequent generations, if it provides a selective benefit it might even become predominant. Reproductive isolation of a population allows different changes to accumulate in one population versus another. Genetic drift alone can lead to massive changes in appearance, and even reproductive compatibility between populations.



    This diagram shows the habitats of North Atlantic gull species, and the arrows represent the ability to breed. As you can see numbers 1 and 7 can/do not interbreed, but there is still gene flow, albeit limited, between them because of the interbreeding between the other species. If gulls 2-6 went extinct you would have two entirely isolated gull species, that would increasingly diverge over time as different selective pressures and mutations occur in the different populations.
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    Quote Originally Posted by The Finger Prince
    So the SAME mutation must occur MULTIPLE TIMES SPONTANEOUSLY in an "isolated" population, presumably so that the mutants can find each other and reproduce, AND confer enough of an advantage so that the "fittest" survive(as if they don't always, that is what makes them fit, innit?) to pass along these genes.

    Where do dominant/recessive Mendelian genes enter into all this then, because only a certain percentage of offspring express it, depending?
    Beneficial mutations are very rare. The likelihood of two individuals of the same species having the same beneficial mutation and live at the same time and in the same geographical area is infinitesimal. One individual may have a mutation, and if it's beneficial, the chances this individual will reproduce are higher than others without the beneficial trait. Some of the offspring of this individual will bare the beneficial trait, and will also be able to produce more offspring, and so on for many generations.
    As for the mendelian genetics, if the trait expressed is highly beneficial, it will likely reach fixation (meaning all members of the species express this trait) whether or not it is recessive or dominant. For a dominant allele though, it'll take less time. That is if you assume AA and Aa express the trait we are discussing (not a good habit, assumptions, but for simplicity sake let's just say).
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  12. #11  
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    Quote Originally Posted by Beard Baron
    .

    Beneficial mutations are very rare. The likelihood of two individuals of the same species having the same beneficial mutation and live at the same time and in the same geographical area is infinitesimal. One individual may have a mutation, and if it's beneficial, the chances this individual will reproduce are higher than others without the beneficial trait. Some of the offspring of this individual will bare the beneficial trait, and will also be able to produce more offspring, and so on for many generations.
    As for the mendelian genetics, if the trait expressed is highly beneficial, it will likely reach fixation (meaning all members of the species express this trait) whether or not it is recessive or dominant. For a dominant allele though, it'll take less time. That is if you assume AA and Aa express the trait we are discussing (not a good habit, assumptions, but for simplicity sake let's just say).
    Examples of beneficial single point mutations?
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    WYSIWYG Moderator marnixR's Avatar
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    i assume that by beneficial you mean any trait that promotes both your survival and your ability to reproduce ?

    i always get uneasy when people brandish the term "beneficial mutation" without having thought about what it really means

    whereas it's easy to identify detrimental mutations (they usually end up as spontaneous abortions, stillbirths or predation on the young and weak), beneficial traits are only so for a given set of circumstances - e.g. during a drought year on the Galapagos finches with big beaks are favoured since they can break open the bigger, harder seeds, but they do less well during El Nino years where their advantage disappears

    or closer to home, would you say a less-pigmented skin is a beneficial mutation ? only if you live in an environment where there's not much sun, and you need to build up your vitamin D levels - place the same person in sunnier climes (as many of us do when going on holiday), and that beneficial trait becomes a detrimental one, with a risk of sun burn and skin cancer
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    Forum Freshman Beard Baron's Avatar
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    i assume that by beneficial you mean any trait that promotes both your survival and your ability to reproduce ?

    i always get uneasy when people brandish the term "beneficial mutation" without having thought about what it really means
    Indeed, I did mean it in that manner. It was foolish of me to not specify; I'm still getting the hang of the forum, you see.

    As for a fun example, let's look the evolution of the wing. In eumaniraptorids, veined feathers on the bottom part of the arm could have been used as a method of ensnaring prey in somewhat of a net. Consider a raptor chasing a prey item. If it had large veined feathers on its long, outstretched arms, the prey item would be more limited in its path; it would have to go straight forward (when in close proximity) rather than dart from side to side. A 'beneficial' mutation which would allow a greater hunting efficiency could be longer arms or longer feathers.

    Edit: Pardon my failure at quoting. I'll figure it out eventually, I promise.
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    Veracity Vigilante inow's Avatar
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    Quote Originally Posted by Beard Baron
    Edit: Pardon my failure at quoting. I'll figure it out eventually, I promise.
    Your syntax is correct (or pretty close). It is currently disabled since you have so few posts. Just a few more and it will be working per expectations.
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  16. #15  
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    Quote Originally Posted by prince
    Examples of beneficial single point mutations?
    Last I recall running across the estimate, the average successfully developing human embryo is carrying more than a hundred single point mutations in expressed (protein coding) stretches of their nuclear DNA.

    And or all of them are potentially beneficial, alone or in combination, depending upon the circumstances of life to be encountered by the person.

    As clairvoyance remains undeveloped among the sciences, the label "beneficial" applies only in retrospect, and is always contingent.
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