Clades, cladons, and "cladifications"
kinman2 at YAHOO.COM
Mon Jun 14 14:26:44 CDT 2004
I would also tend to agree with Pierre's characterization. But although there are two systems involved, they are combined into a single classification (see classifications I have presented on taxacom on Magnoliophyta, Diptera, and various other taxa). It was the lack of such a methodology in 1979 that David Hull was referring to. Actually I had developed my system in 1977-78, but it wasn't published until 1994.
I don't include an actual numerical degree (amount) of divergence in my classifications, as it would require more resources than I have available. However, Kent Carpenter did do this for his "Optimal Cladistic and Quantitative Evolutionary Classification" of Caesonid fishes (Syst. Zool., 42:142-154). Thus the methodologies are out there, ready to be used and refined. The biggest problem is the notion (propaganda) that paraphyly is unnatural and to be avoided at all costs. It simply is NOT true (see Mayr and Ashlock's 1991 textbook, not to mention a great deal of botanical literature---I guess I should have been a botanist).
From: HJJACOBSON at AOL.COM
In a message dated 6/14/2004 10:39:26 AM Pacific Standard Time, pierre.deleporte at UNIV-RENNES1.FR writes:
> I don't mean it is not utilizable, I mean that there are two systems. It cannot logically be otherwise.
I agree with this characterization. What I had meant say was that both types of informantion, degree of divergence and cladistic branch topography, could be mixed to create a classification. The problem is that the person using the classification cannot extract the different information. She can not reconstruct the cladogram or phenogram from just looking at the information. She may be able to reconstruct the phenogram topology but not the degree to which each branch diverges, and the degree (amount) of divergence is what penetic classification is all about.
I admit that I am not familiar with Ken's methods, but I do know that he classifies using both paraphyletic and monophyletic groups, and he uses a set of numbers and symbols to identify them. Base on this very limited understanding of his method (and I further admit that I'm on thin ice here), I might guess that a taxomomist could extract the topology of the group, but not the degree (or amount ) of divergence. And I think this was Hull's point.
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