paraphyly

Bengt Oxelman bengt.oxelman at SYSTBOT.GU.SE
Thu Jun 12 23:38:48 CDT 1997


>At 10:00 PM 06-12-97 +0200, Bengt Oxelman wrote:
>
>>This is nonsense and the result of a confusion of species as taxa (Linnean
>>categories) and species as evolutionary units. With this reasoning there
>>would be no monophyletic taxa at all.
>
>Exactly my point!!

Well, then there is perhaps not much room for discussion. A monphyletic
group can be defined quite simply as all taxa sharing a common ancestor.
The problems start when we try to invoke process properties of taxa (i.e.
the terminal units). Of course monocots are monophyletic (or at least the
current knowledge speaks strongly in favor for that). My point is that it
is meaningless to equate the branches in the dendrogram with the terminal
units (as well as clusters of them). Unfortunately, there is much confusion
in common biological terminology due to the double meaning of the word
species. Yes, I try to classify taxa that are historical (monophyletic)
units, whether they are given formal rank of species, genus or whatever.
But it should be very clear that they do not participate in evolution
themselves, they are the result of evolution. The 'thing' (singularity,
system of replicators) that actually participitates in evolution needs
another concept, entirely decoupled from Linnean categorical ranks, and it
has nothing to do with taxonomy.

--------------------------------------------------------------------------
Bengt Oxelman
Department of Botany
Stockholm University
Lilla Frescativ=E4gen 5
S-106 91
Sweden

Phone: +46 8 161215
=46ax: +46 8 165525
Internet e-mail: bengt.oxelman at systbot.gu.se




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