Comments to Cladistics/Eclecticism, part 1

[Susanne Schulmeister]

Dear All,

I am a cladist and have been watching the Cladistics
vs Eclecticism debate for a while. I would like to
make a number of comments about various issues which
are part of this debate.

1. Taxa and clades
The term “taxon” is used with slightly different
meanings by different people, even in the literature.
Some people use taxon as a synonym to clade, i.e. a
monophyletic group (NAMED OR NOT). Among them Tom
DiBenedetto, I believe. Other people use taxon to mean
a NAMED monophyletic group, even others use it to mean
a NAMED group of species (monophyletic or
paraphyletic). Among the latter are Skala Zdenek and
Ken Kinman, I think.
This difference was the source of the misunderstanding
that the others thought that Tom wants to name EVERY
discovered clade. When Tom was talking about all the
taxa in a cladogram, he simply meant all the clades,
he didn’t mean that he wanted to name all the clades.
Personally, I find the distinction of clades as (named
or unnamed) monophyletic groups and taxa as named
clades quite useful. However, since I am a cladist
(strict cladist for Ken), I will not use taxon to mean
“named group of species”. By the way: for the same
reason I use the word monophyletic for what
evolutionary taxonomists (eclecticists) call
holophyletic.



2. Cladistics
Cladistics is not just a method with a set of rules.
It is a beautiful body of theory and philosophy which
can only be understood in its entirety, not in bits
and pieces through some emails which treat
disconnected parts. For example, cladistics
necessitates a phylogenetic species concept. The
evolutionary taxonomists (eclecticists,
Mayr-Simpsonites, Mayr-Ashlockians 
) on this list --
and some people who call themselves cladists – are
entrapped in a morphological species concept.
Cladistics is incompatible with a morphological
species concept.



3. Synapomorphies and clades
In cladistics, the characters (or rather:
synapomorphies) are used to discover the evolutionary
history of organisms. Synapomorphies are traces of
history that we use to infer this history. Taxa are
not based on synapomorphies. Taxa are based on clades.
Taxa are (named) clades. This is an important
distinction.

To be continued...

=====
New journal: ODE - Organisms, Diversity and Evolution
by the Gesellschaft für Biologische Systematik.
http://www.urbanfischer.de/journals/ode

Susanne Schulmeister
Institute of Zoology and Anthropology
University of Göttingen, Germany

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