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Convergent evolution

  1. Jan 8, 2010 #1
    I realize this might not be likely, but I'm sure it could happen. I'm just trying to figure out how improbable this scenario may be:

    How likely is it that two different species could undergo convergent evolution to such an extent that members of the different species could interbreed? In other words, become one species?
     
  2. jcsd
  3. Jan 8, 2010 #2

    Borek

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    Staff: Mentor

    For all practical purposes impossible.
     
  4. Jan 9, 2010 #3
    Perhaps not interbreed, as DNA is too complex, and only slight variations result in sterility.

    However, very high degrees of symbiotic behavior exist in nature, to the point where one species cannot live without the other.
     
  5. Jan 9, 2010 #4
    I think there's a problem with the pressumed definition of the word species here. Species are not really differentiated by 'what they can interbreed with' but more like 'what they can breed with normally'.

    An example coming to my mind immidiately of two seperate species that have evolved are lions and tigers. They both come from the Panthera genus but I don't see why that matters, they fit the OP.

    http://en.wikipedia.org/wiki/Liger
    Lions and tigers have definitely gone on different evolutionary paths and they can interbreed.

    Now for two completely different species different up to say Family were to evolve completely seperate they would probably not be able to interbreed. This doesn't mean that they wouldn't be able to and even if they do that doesn't make them 'the same species'

    EDIT: Just to make sure that this is understood interbreeding between species does occur, this does not make them the same species. The outcome is just called a hybrid. There are plenty of known hybridizations... the highest level of difference I have seen for hybridization is genera but I've never really looked to deeply into this subject. Genera is quite a distant seperation for two different species though.
     
    Last edited: Jan 9, 2010
  6. Jan 9, 2010 #5

    Borek

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    My guess was that the question asks something like "can ichtiosaur interbreed with dolphin" - as that's a textbook example of convergence.
     
  7. Jan 11, 2010 #6
    As detailed by “Sorry!” Interbreeding of closely related species is all but impossible ... there are many examples of hybrids in all "higher" taxa even in the well known mammals. E.g. within the same genus (Tigon / Liger) and in different genera (Rhinos black x white), false killer whale x dolphin (http://en.wikipedia.org/wiki/Wholphin" [Broken])… . Some older Zoologists continue to ignore this, while most Botanists never adopted the “biological species” concept of Ernst Mayr. Strict hybridization barriers between closely related and therefore to some extend genetic similar, but in a morphological sense clearly different species, might - or might not be present.

    Even very unrelated species can exchange DNA (This isn't "interbreeding" in a common sense) see this http://www.wired.com/wiredscience/2010/01/bornavirus-in-human-dna/" [Broken]

    But to come back to your question: Convergent evolution is the result of similar selection on phenotypes due to shared environments or lifestyle ... so certain parts of the bodies in unrelated taxa get similar during convergent evolution, as certain forms are advantageous in a certain environment. Convergent evolution will not result in two unrelated species being the "same" in every aspect, as other parts of their bodies will not undergo convergent evolution and stay different. E.g. despite being adapted to flying, bats never evolved the beaks of birds, or their elaborated breathing system. Two species being too similar to each other in morphology and lifestyle will result in large ecological similarities, which will cause heavy interspecific competition and result in extinction or geographic exclusion. So there is even a mechanism that hinders unrelated species in being too similar. E.g. it’s highly questionable whether dolphins could have evolved in the presence of ichtyosaurs as the dolphin niche was already occupied by the very similar ichtyosaurs.

    While phenotypes will get similar during convergent evolution, there is no reason to think that genotypes will evolve more than random similarities. Therefore interbreeding of birds and bats, whales and fish, or ichtyosaurs and dolphins is highly unlikely and as said by Borek:
     
    Last edited by a moderator: May 4, 2017
  8. Jan 11, 2010 #7
    I was only addressing the 'interbreeding' species aspect of the OP since you had already answered the converngent evolution portion :smile|:
     
  9. Jan 12, 2010 #8
    Last edited by a moderator: May 4, 2017
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