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Question about cladistics

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Question about cladistics

Postby Bob_B » Wed Dec 15, 2004 4:55 pm

Hello! I am new to this forum and will post a few questions from time to time. I am a biologist, schooled so long ago I hesitate to mention. Biology has come a long way in that time -- the shift in emphasis from descriptive biology or natural history to molecular biology, genetics, etc. All for the better, I suppose, but this old fire horse sometimes feels like a foreigner in his once cozy club. So, my first question...

Cladistics is said to be the classificaltion of organisms based on their actural genetic similarity, viz., divergences or branches on the family tree. Classical biology would classify on the basis of form and structure with the assumption that similarities presusmed close relationship (with allowances, of course, for parallel evolutionary cases).

So what is so revolutionary about cladistics? The old method of classification ATTEMPTED in its limited way to determine actual relationships, did it not? Presumably, cladistics utilizes the latest information gained in genetic studies to pinpoint acutal relationships, doesn't it?

And finallly, another question, with genetic studies are we not now capable of determining with certainty the actual relationships between all animal species. And if so, where does one see this "new" classification to get an idea just how closely one animal type is related to another?

A lot to talk about, I know. Hope it is appropriate to this forum.

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Postby biostudent84 » Wed Dec 15, 2004 5:20 pm

Very interesting point. Reading your description of Cladstics, I could think of one major advantage it has over the "old school" style ot taxonomy. In the old style, it is possible that some organisms have been grouped together due to convergent evolution. Remember that biologists once thought that the fungi were plants based on their overall look? Most fungi grow where plants are often found, and the mushroom has a similar look to a tree (a strange looking tree, albiet).

I'm currently reading a book on human evolution, and this idea comes into effect when trying to decide on exactly which of our fur-covered cousins we are mostly related to. When we look exclusively at body structure, the ape is the most closely related. When we look at pure DNA, we find the chimp. Strangely enough, we've also looked at behaviorial practises...and there we find the bonobo.
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