Message 2001-06-0053: Re: subscribers

Wed, 02 May 2001 17:34:01 -0700

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Date: Wed, 02 May 2001 17:34:01 -0700
From: Richard Olmstead <>
Subject: Re: subscribers

The PhyloCode makes no provision for naming paraphyletic groups.  If
Lophotrochozoa turns out to be synonymous with Bilateralia, then it simply
is dropped as a formal name - Bilateralia remains perfectly good for the
group.  If anyone wants to use informal names for paraphyletic groups, such
as 'fish,' 'reptiles,' 'green algae,' 'bryophytes,' or 'lophotrochozoa,'
that's up to them.  After all, nomenclature, like language, is for
communication and in language, precision makes for clarity.

It seems to me that the goal of those who promote PhyloCode is to convince
systematists who believe that taxonomy should be a system of naming
monophyletic groups to follow a series of naming principles laid out in the
PhyloCode.  Systematists who want to continue to give formal recognition to
paraphyletic groups are a shrinking minority in our field and even many of
the most vocal opponents of PhyloCode oppose such taxonomy.

There is nothing in the neo-Linnaean hierarchy of ranks that is
incompatible with a strictly monophyletic classification.  Many who oppose
the PhyloCode think we can do just fine within that framework.  I happen to
disagree.  The argument against ranks and binomial nomenclature is separate
from the argument against recognizing paraphyletic groups.  Both are
important elements of PhyloCode, but I think this recent string of comments
hasn't kept them separate.

Dick Olmstead

>      In the case at hand, if cladistically-defined and "precise"
>Lophotrochozoa turns out to be a synonym of Bilateralia, the cost of that
>precision is going to be pretty steep.
>     The contents and characteristics will expand considerably (with the
>addition of all deuterostomes and ecdysozoans).  Numerous trees and cladograms
>in the intervening literature will be incorrect, and the accompanying text
>confusing as well for those unaware of the whole story.  Lots of confusion and
>inaccuracy in the name of precision (no thank you).
>      And what a waste of a name.  Couldn't call the paraphyletic group
>lophotrochozoans any more.  Would be stuck with an explanation like:
>     Lophotrochosozoa was formerly erroneously restricted to the
>"non-ecdysozoan, non-deuterostome bilateralians", but then later more complete
>cladistic analyses showed this clade to be a heterodefinitional synonym of
>      But in the meantime, what I fear most is that some workers, assuming
>that Ecdysozoa and Lophotrochozoa are really sister groups, might begin using
>ecdysozoans as outgroups in cladistic analyses of groups in the supposed clade
>Lophotrochozoa (as we see it in the literature from 1995-2001).  This would
>produce an even bigger mess.
>      My main warning on this issue is that neither ecdysozoans (nor
>deuterostomes) should be used as outgroups to the presently constituted
>Lophotrochosozoa.  I can see how workers would be tempted to do this, since
>outgroup selection was one of the criticisms levelled by Conway Morris et al.
>That is one criticism I definitely  wish they had not made, because it could
>have workers cladistically jumping out of the frying pan and into the fire
>(making the outgrouping problem worse rather than better).  Better to use a
>cnidarian outgroup than to use an ecdysozoan (which I believe is really an
>         That's my advice,  Ken

Richard Olmstead
Associate Professor of Botany and Herbarium Curator
Editor, Systematic Biology
Department of Botany		For express mail services:
Box 355325				Department of Botany
University of Washington			Hitchcock Hall Rm 423
Seattle,  WA  98195-5325			University of Washington
USA					Seattle, WA  98195

Office: 206-543-8850
lab:            206-543-6594
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