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Thread: When a species evolves ... when you consider that we have ca new one?

  1. #1 When a species evolves ... when you consider that we have ca new one? 
    Universe Supervisor dapifo's Avatar
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    When an species A (human, cat, dog,...) evolves by DNA mutations .... when we can consider that the new being B is another species?

    Could be when the DNA of both species (A & B) can no longer reproduce between them?


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    Forum Professor pyoko's Avatar
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    I found this an interesting question and am reading through:

    Hybrid (biology) - Wikipedia, the free encyclopedia

    and

    Genetic pollution - Wikipedia, the free encyclopedia


    It is by will alone I set my mind in motion.
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    Universal Mind John Galt's Avatar
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    Whenever it is convenient to do so. Species are an artificial construct of humans designed to facilitate our understanding of biological relationships.
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    Brassica oleracea Strange's Avatar
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    There is a very good description of the problems associated with defining a species here: Observed Instances of Speciation

    Note the "biological definition" (being able to interbreed) would make Chihuahuas and Great Danes different species.
    ei incumbit probatio qui dicit, non qui negat
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    For one introduction to evolutionary speciation spend 3 minutes with this video. It starts out with 'ring species' and goes from there.

    Ring species -- the abridged version - YouTube
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
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    Universal Mind John Galt's Avatar
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    Quote Originally Posted by Strange View Post
    Note the "biological definition" (being able to interbreed) would make Chihuahuas and Great Danes different species.
    Not if you give the Chihuahua a step ladder.
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    Quote Originally Posted by dapifo View Post
    When an species A (human, cat, dog,...) evolves by DNA mutations .... when we can consider that the new being B is another species?

    Could be when the DNA of both species (A & B) can no longer reproduce between them?
    You're referring to the species problem. In short, we can make a definition as precise as we want to, but for convenience we will still void it on certain occasions.
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    Forum Radioactive Isotope sculptor's Avatar
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    long ago, a female cousin told a joke about an ant:
    It seems that the ant had an ego that vastly exceeded his diminuative size. Stomping around in the jungle looking for something to do, he came upon an elephant, and thought "I know, I'll rape an elephant" so, he ran up the elephants tail, and plunged in as far as he could go. Just then, a coconut fell from a tree and hit the elephant on the head, whereupon, the elephand let out a groan, and, hearing this, the ant said"suffer baby suffer".
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    Forum Professor pyoko's Avatar
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    Quote Originally Posted by John Galt View Post
    Whenever it is convenient to do so. Species are an artificial construct of humans designed to facilitate our understanding of biological relationships.
    It is a human construct, but so is the prerequisites to classify something as a scientific "theory". For example, the recent Higg's Boson scientists declared that they will call it a "theory" only when they have meet the "requirement of level of certainty that meets one chance of error in 1.7 million". As they stand now, it is about 1 in 16000, so it is "a pretty good bet", but they aren't calling it a theory yet.

    So this is a valid question. How in science have people defined when a species is a new one?
    It is by will alone I set my mind in motion.
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  11. #10  
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    when a species is a new one?
    a) When it's one they haven't seen before.

    b) When one they knew but thought was the same as, or a variety of, a known species turns out to be unable to reproduce with that group.

    Can't think of any other criteria.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
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    Forum Professor pyoko's Avatar
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    What about percentage of DNA difference? Would be more quantitative. Must admit I see even that being too much of an umbrella term for it. Maybe there just isn't any "better way" than the one you described above.
    It is by will alone I set my mind in motion.
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    What about percentage of DNA difference?
    I think they do that after they discover the reproduction problem. Just which DNA step was the final one in making a couple of variations within a species become genetically incompatible.

    Of course, it's more often done to find the code distinguishing differences in shape, size, colouring as well.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
    "nature is like a game of Jenga; you never know which brick you pull out will cause the whole stack to collapse" Lucy Cooke
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    Forum Professor pyoko's Avatar
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    Quote Originally Posted by adelady View Post
    What about percentage of DNA difference?
    I think they do that after they discover the reproduction problem. Just which DNA step was the final one in making a couple of variations within a species become genetically incompatible.

    Of course, it's more often done to find the code distinguishing differences in shape, size, colouring as well.
    I guess they can trace a timeline with genetic markers and somehow bring the markers into consideration when calculating the % difference. Or something. Or nothing.
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