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Date: Fri, 13 Oct 2000 09:41:08 -0400
From: Philip Cantino <cantino@ohiou.edu>
To: PhyloCode@ouvaxa.cats.ohiou.edu
Subject: Fwd: Re: RE: RE: Nathan Wilson's question
I wrote: >"I think that what Gerry had in mind (and he should correct me if I >am misinterpreting) is that some of the genome of species 3 is in >clade A and some in clade B. If so, the least inclusive clade that >includes the full genome of species 3 is the larger one identified by >Gerry, thus the application of the name for clade Z is ambiguous." > Kevin wrote: >To my way of thinking, that interpretation is incorrect. If we're >concerned with naming monophyletic groups of genes or genomes rather >than species, then the species in which the genes or genomes occur >are irrelevant. On the other hand, if we're concerned with naming >monophyletic groups of species (clades), then the fact that part of >the genome of species 3 comes from one source and another part from >another means only that certain clades are partially overlapping in >terms of their species composition. It doesn't create any ambiguity >regarding the application of the name. The only way to reach the >conclusion that the name should be applied to the larger clade in >Gerry's example (and therefore that application of the name is >ambiguous) is to confuse levels by substituting genomes for species >in the definitions (which is effectively what has been done in the >diagrams that have species 3 in two places). Another way to see the >error is to consider the statement "some of the genome of species 3 >is in clade A and some in clade B". While true, what this statement >fails to acknowledge is that the part of the genome that is in clade >A is also in clade B, and the part of the genome that is in clade B >is also in clade A. The very notion of hybridization implies that >that we can no longer treat clades A and B as entirely separate >(mutually exclusive) entities. I agree with your analysis but others may not. If a careful thinker with a thorough understanding of nomenclature (e.g., Gerry) can interpret a hybrid species as belonging partially to one clade and partially to another non-nested one, rather than fully to both clades, isn't it likely that other users of the PhyloCode will also interpret the situation this way in the absence of a clarification within the code? One solution is the one that Michel proposed and which I supported in an earlier message. Perhaps a better solution would be simply to include a note somewhere in the PhyloCode clarifying that, for nomenclatural purposes, a hybrid species belongs fully to all clades (including non-nested clades) that each of its parents belongs to. An example could be provided to show the context in which the note is relevant. 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