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Date: Tue, 10 Oct 2000 11:28:01 -0400
From: Philip Cantino <cantino@ohiou.edu>
To: PhyloCode@ouvaxa.cats.ohiou.edu
Subject: Fwd: RE: Nathan Wilson's question
It is rather late to re-enter this discussion, but other responsibilities prevented me from keeping up with it last week and I didn't get a chance until now to wade through the various contributions. I am confused by Gerry Moore's position, as presented in his first message on this subject and referred to subsequently. GM: > I actually see the issue that Nathan Wilson brought up as potentially >being problematic, since a species that may eventually be shown to belong to >multiple nonnested clades may be used in phylogenetic definitions (as a >specifier) _prior_ to the knowledge that the species actually belonged to >more than one nonnested clade. > For example, let's say Clade Z is defined as the least inclusive clade >containing species 3 and species 4. Species 3 is then shown to have >originated through the hybridization between species in Clade A and Clade B. >When the definition was originally formulated it was believed that species 3 >was a member of only Clade A (not B) and the circumscription of Clade Z was >exclusive of Clade B. Doesn't the circumscription of Clade Z have to >include all nonnested clades to which each specifier (see Art. 11.1) is a >member (i.e., the circumscription of Clade Z will have to be expanded to >include Clade B to accommodate specifier Species 3 being a member of the >nonnested Clades A and B)? I don't understand why Gerry thinks that the circumscription of Clade Z must include all nonnested clades to which each specifier belongs. He refers to Art. 11.1, perhaps meaning the last sentence of this article: "If subordinate clades are cited in a phylogenetic definition of a more inclusive clade, their specifiers must also be explicitly cited within the definition of the more inclusive clade." However, this sentence just says that if you want to cite a subordinate clade (rather than a species or specimen) as a specifier, you must go on and state the specifiers of the subordinate clade. It says nothing about the named clade containing all clades to which each specifier belongs. Clearly, the named clade can't include all nested clades to which each specifier belongs (if it did, every name would refer to the clade comprising all of life). Why should it include all non-nested clades to which each specifier belongs? Phil Philip D. Cantino Professor and Chair Department of Environmental and Plant Biology Ohio University Athens, OH 45701-2979 U.S.A. Phone: (740) 593-1128; 593-1126 Fax: (740) 593-1130 e-mail: cantino@ohio.edu