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Date: Thu, 28 Sep 2000 13:53:08 -0400
From: "Moore, Gerry" <gerrymoore@bbg.org>
To: 'Nathan Wilson' <velosa@cinenet.net>
Cc: PhyloCode@ouvaxa.cats.ohiou.edu, "'cantino@ohio.edu'" <cantino@ohio.edu>
Subject: RE: Nathan Wilson's question
NW: Gerry Moore also brings up an interesting point about using members of non-nested clades as specifiers, but I think the example he gave doesn't quite make the point. As Philip Cantino points out there is no problem under the current definitions if one of the two species belongs to two non-nested clades. Where did Phil say that? Under phylogenetic nomenclature a clade's circumscription must include all positions where the specifiers show up. To me whether or not it is one or two (or three etc.) of the specifiers that happens to occupy nonnested clades is irrelevant. Are you saying that in my example, Clade Z's circumscription would not have to be expanded to include Clade B because only one of the specifiers (species 3) was shown to occur in more than one nonnested clade? If so, I don't follow (more below). NW: However, there is a problem if both species belong to the same two non-nested clades. If that's the case then a node-based clade defined using those two species has no clear definition since there are now multiple most recent ancestors and no clear way to choose between them. I see this very differently. To me, the circumscription of the taxon (clade) defined using these specifiers that are now known to occupy multiple nonnested clades has to be expanded so as to encompass all the nonnested clades that the specifiers are now known to occupy. Again, I fail to see why there is a problem only if two of the specifiers (as opposed to one) belong to nonnested clades (see above discussion). To me the name of the clade still has a very clear definition; the original circumscription simply needs to be modified (expanded) to include this new information (i.e., a specifier occupying nonnested clades). I stand by my original conclusions I made regarding the hypothetical example I presented previously. Cheers, Gerry Moore 28 Sep. 2000