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RE: Definitions

>Firstly, I want to point out that stem- and node-based taxon definitions are
>part of phylogenetic taxonomic nomenclature (in other words, a particular
>scheme for labelling parts of the tree of life).  This is not exactly the
>same thing as cladistics, or phylogenetic systematics.  The latter is a
>methodology for estimating patterns of shared common ancestry (that is,
>attempting to reconstruct the shape of the tree of life).

As a further clarification, "cladistics" has been used in the literature
for two different things - a methodology for estimating relationships
(parsimony) and the recognition of monophyletic groups and only
monophyletic groups in taxonomy.  One can apply some other method
(likelihood, for example) and still be a strict cladist with respect to
taxonomy (or to phylogenetic nomenclature, which is the placing of
phylogenetically-defined names on the taxa we recognize).

Unfortunately, we still see people in the literature confusing the two.
Have a look at Vermeij's response to his flotilla of criticisms for an
example of what should not be happening anymore.


Christopher A. Brochu
Assistant Professor
Department of Geoscience
University of Iowa
Iowa City, IA 52242

319-353-1808 phone
319-335-1821 fax