[Previous by date - Why does the PhyloCode use a hierarchy?]
[Next by date - Re: Nathan Wilson's question]
[Previous by subject - My nude pics! (X7D2w0)]
[Next by subject - New Dinosauricon Taxon Pages: _Therizinosauria_]
Date: Tue, 26 Sep 2000 17:04:35 -0400
From: Philip Cantino <cantino@ohiou.edu>
To: PhyloCode@ouvaxa.cats.ohiou.edu
Subject: Nathan Wilson's question
Hello, Since no one else has responded to Nathan Wilson's question, I will make a stab at it. I discussed this with Kevin over lunch today, so the ideas are partially his (I'll leave it to him to correct me if I misrepresent any of them). Nathan is concerned about the effect of interclade genetic transfer on clade nomenclature. I don't think this is a problem if one accepts that a species may belong to two non-nested clades. For example, if clades A and B are non-nested, and members of species 1 (in clade A) and species 2 (in clade B) hybridize to produce an offspring that gives rise to species 3, species 3 is a member of both clade A and clade B. This must be the case because species 3 is simultaneously a descendant of both the immediate common ancestor of clade A and the immediate common ancestor of clade B. Similarly, if genetic material is transferred by some other means from species 1 to species 2, then one might argue that species 2 (but not species 1) is a member of both clades A and B. It is debatable whether it is worth treating species 2 nomenclaturally as belonging to two non-nested clades if only a small percentage of its genetic material came from clade A, but the principle is the same. There is nothing in the PhyloCode that prohibits naming a clade, some species of which belong to another non-nested clade, so I don't think that the issue that Nathan raised requires that the wording of clade definitions be modified, as he suggests. However, the taxonomic issue of species belonging to non-nested clades is an interesting one that I don't think has been addressed in the literature. It is a significant departure from the traditional rank-based system, in which a species may belong to only one genus, one family etc. (I am comparing ranks to clades here by way of analogy, not suggesting that they are the same thing.) 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