Cladistics and "Eclecticism"
tdib at OCEANCONSERVANCY.ORG
Wed Jan 30 11:45:09 CST 2002
From: Tom Wendt
...cladists are interested only in
branching patterns, which they equate with "the history of life." The
amount and type of evolutionary change that occurs (or doesn't occur) along
the way is apparently of no interest, or at least not worthy of inclusion
in a classification.
I disagree completly with this characterization, and I tried to make this
point in earlier posts. Cladists are interested in character change to the
same degree as anyone else, and have, in fact, a far superior protocol for
presenting that information to the rest of the scientific community. The
"amount and type of evolutionary change" that Tom Wendt refers to are
historical instances of character state transformation. These are the
evidentiary base for cladistic classification, and these transformations are
mapped onto the cladogram at their appropriate node. All of the character
information is there, and it is there in an accurate historical framework.
Eclecticists, as Ken calls them, feel that amount
and type of change should be included in the classification (in addition to
branching patterns), as difficult as that may be to do in practice.
I think that this characterization is not quite precise. It is not that the
eclecticists feel that character information should be included in the
classification - rather they feel that this information should be used to
define the framework of the classification. That is a hugely different
matter - for they allow the character information to obscure the framework
of lineage divergences.
What makes more sense to you Tom?
Case 1-,A scientific literature which presents an accurate rendition of the
lineage divergences with the character transformations mapped onto that (for
example - we have taxon A, which is one of the subtaxa of higher taxon B,
and we can see this relationship onthe cladogram-, and we have a series of
marks on the cladogram indicating the number of character transformations we
have discovered, and it shows that there were an unusually high number of
transformations in the taxon A branch
Case 2- A scientific literature that presents a classification in which
Taxon A and Taxon B are ranked at an equal level because some systematist
(who had private access to the information laid out in case 1) decided that
the high number of transformations in the A line warrented a presentation of
the two taxa as being equal, in some sense.
Which of these two cases is an honest and accurate rendition of scientific
discoveries, and which is more useful to the scientific community, or to
anyone who wishes to understand the history of life?
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