2000 years of stasis

Philip Cantino cantino at OAK.CATS.OHIOU.EDU
Sat Feb 5 15:50:57 CST 2000


Mark Garland wrote:
>Phylogenetic nomenclature attaches a definition, not a diagnosis, to each
>name, and therefore to each taxon.  (See lots of papers by de Queiroz and
>others about "phylogenetic *definition* of taxon names" or something
>similar.) That definition boils down to the invocation of a common ancestor
>and all of its descendents.
>I would think attributes of the members of a group would be involved in any
>diagnosis of a group.  But in phylogenetic nomenclature, attributes of the
>named group--other than synapomorphies--are irrelevant.

In a previous message, Mark wrote
"We ought to recognize that identification is a fundamental part of
taxonomy--the part where taxonomy has an effect on the "real world," as
opposed to the parallel cladistic universe.  As someone in that "real" world,
I have to favor a continuation of some sort of hierarchical naming system for
identification purposes."

I certainly agree with Mark that identification is a very important
activity and that any taxonomic system should facilitate identification.
However, the kind of nomenclature that is used (phylogenetic or Linnaean)
has no bearing on whether a classification (or rankless taxonomic system)
is useful for identification.

How you define a name is an entirely different thing than whether a
description is provided for the named taxon.  Phylogenetic nomenclature is
not the only system that defines taxon names.  Our traditional "Linnaean"
system defines names by linking them with a rank and a type.  We don't
usually refer to this as a definition, but it functions as one.  For
example, in the current system, Lamiaceae is defined as the taxon of family
rank that includes Lamium.  In phylogenetic nomenclature, Lamiaceae might
be defined as the least inclusive clade that contains Lamium and Congea.
Neither definition by itself would help you identify a member of the
Lamiaceae when you see one.  To do this, you need descriptions and keys,
and these can (and should) be provided no matter which system of
nomenclature is used.


Philip D. Cantino
Department of Environmental and Plant Biology
Ohio University
Athens, OH 45701-2979

Phone: (740) 593-1128
Fax: (740) 593-1130
e-mail: cantino at ohio.edu

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