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Date: Tue, 06 Feb 2001 11:31:01 -0600
From: "David M. Hillis" <dhillis@mail.utexas.edu>
To: PhyloCode@ouvaxa.cats.ohiou.edu
Subject: Re: apomorphy-based names
At 11:38 AM -0500 2/6/01, Kevin de Queiroz wrote: >my point was not the VP workers are more inclined to use explicit >apomorphy-based definitions but that it is often clear that they >really have an apomorphy-based concept of certain clades even when >they define the names of those clades using other types of >definitions! And that's true for some of the clades of non-crown >"birds," where node-based definitions are used when the authors seem >to have an apomorphy-based concept of the clade they are intending >to name. Jacques may be able to provide more details on this. I don't have any problem with this...I suppose we all often think about clades from the standpoint of what they look like. But I think we can be more explicit and phylogenetically clear in our definitions by naming clades using node-based and stem-based definitions, even if we originally conceptualize those clades based on apomorphies. I agree with David Baum that a nomenclature that expresses an explicit tree is preferable to one that relies on the supposed fixation of a particular trait that may or may not be unambiguously defined or interpreted. Naming node-based and stem-based taxa seems to be the trend, even in vertebrate paleontology, and even, as Kevin points out, when the clades are originally conceptualized on the basis of particular apomorphies. I think that is a good thing. David M. Hillis Director, School of Biological Sciences Director's office: 512-232-3690 (FAX: 512-232-3699) Alfred W. Roark Centennial Professor Section of Integrative Biology University of Texas Austin, TX 78712 Research Office: 512-471-5792 Lab: 512-471-5661 FAX: 512-471-3878 E-mail: dhillis@mail.utexas.edu