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hommologous structures

Discussion in 'DAT Discussions' started by arpitpatel86, May 16, 2008.

  1. arpitpatel86

    2+ Year Member

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    is parallel evolution associated with homologous structures?
     
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  3. IdahoDoc

    7+ Year Member

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    Yes, with parallel evolution both the original and new species exists. The homologous structure is what connects the two. An example is with the fins of a whale and the bone in the feet of turtles while they look very different on the exterior you can see that they have similar ulna bones.
     
  4. arpitpatel86

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    would it be correct to say that homologous structures are associated with DIVERGENT and PARALLEL EVOLUTION?
     
  5. doc3232

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    I think divergent E. would be the opposite of homologous structures of 2 species. (I know this is bad grammar).
     
  6. bigstix808

    bigstix808 Mac Daddy Member
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    i'm gonna have to say no on this one...let me explain.

    when two things are evolving "parellel" to each other, the common characteristics evolving are heading towards the same location, but taking a differnt route. this is generally because of the differences in selective pressures for that particular organism. for example, animal X found in the forest or south georgia has a black/brown fur color to blend in to its environment to avoid predation. now animal Y, similar to animal X, found in the fields of the tundra has evolved a black/brown fur color to absorb more heat to keep warm, not because it would help with predation.

    i would use the relationships...

    (1) parellel evolution : analogous structures
    --> same structure, different selective pressures, arbitrary origin (example given above)

    (2) converrgent evolution : analogous structures
    --> same structure, same selective pressures, different origin (bird wing, bat wing)

    (3) divergent evolution : homologous structures
    --> different structure, different selective pressures, same origin (whale flipper, human arm)
     

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