semi-paraphyletic taxa: a new paradigm?

Karstad-Schueler bckcdb at ISTAR.CA
Tue Jan 5 17:35:28 CST 1999


Ken Kinman wrote:

>      "A truly cladistic classification of life would
> require an enormous number of intermediate categories
> and would therefore sacrifice stability and usefulness
> in favor of predictive power."

* I've never understood why, if there are no quantitative criteria of age
or phenetic distance-or-gap to define categories, Linnean categories
continue to clutter up putatively phylogenetic classifications. We deduce
nested hierarchies of taxa, and give each a name, but I've never
understood what we gain by imputing some sort of equivalence between the
Parulidae and Staphylinidae by calling them both "families."

> In order to retain both
> the greater predictive ability of cladistic systems, and
> the practicality, stability and evolutionary-distance
> (anagenetic) information of eclectic systems of
> classification, the use of "semi-paraphyletic" groups
> has been adopted.

> "The semi-paraphyletic markers solve one of the
> major problems that cladists have with eclectic
> classification, namely the paraphyletic placement of two
> sister groups on different taxonomic levels.

* but this dodge (or something else like it) is needed only if there's
some real benefit to retaining categories. Without categories you can
name and discuss as many monophyletic groups as you find, and maybe talk
about the phenetic distance & overlap between sister groups in terms of
various character sets, but I just don't see the need for retaining
Aristotelian categories in a phylogenetic discourse.

I'm obviously wondering about a bigger subject than the "Kinsman System"
here, but I'd be interested to see a non-nostalgic defense of the use of
categories.

fred schueler.
------------------------------------------------------------
Frederick W. Schueler, Aleta Karstad, Jennifer Helene Schueler.
         Bishops Mills, Grenville Co, Ontario, Canada
(RR#2 Oxford Station, K0G 1T0) (613)258-3107   bckcdb at istar.ca
Natural History Exploration, Interpretation, Illustration, & Analysis
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