Paraphyly and names

SKÁLA Zdenek skala at INCOMA.CZ
Tue Jan 29 09:09:58 CST 2002

Tom DiBenedetto:
>Your statement is your statement, purposely designed to sound circular. My
>statement is that monophyletic taxa are best becaue they are based on
>synapomorphy, and synapomorphies are the preferred basis for classification
>because they represent character states considered at their true historical
>level of generality- and thus indicate complete groupings of species that
>share descent from a common ancestor.

It's puzzling. Here are you repeating your circularity even more explicitly - you write:
"...monophyletic taxa are best because ... based on synapomorphy, and synapomorphies are 
preferred...because...indicate complete groupings of species...". Where I am reading you wrong?

>Feathers are not an apomorphy of Aves,
>although they once were considered to be so. For a cladist this means simply
>that the character moves up a node or two,...

Well, your argument was that to have an apomorphy in two taxa of the same rank is to indicate that this apomorphy evolved twice. My response is that this necessarily occurs whenever you do not use some basal apomorphy for the delimitation of a taxon (and, obviously, not all apomorphies can be used so unless we have as many taxa as clades). Evidently this is not dependent on which monophyly concept you prefer and hence fail to be a plausible argument in this discussion.
Anyway, I believe that most of your arguments were already discussed in the current thread so I take to liberty not to respond more; please read carrefully the recent postings.
Zdenek Skala

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