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Date: Wed, 27 Sep 2000 14:01:10 -0400
From: "Moore, Gerry" <gerrymoore@bbg.org>
To: 'Philip Cantino' <cantino@ohiou.edu>
Cc: PhyloCode@ouvaxa.cats.ohiou.edu
Subject: RE: Nathan Wilson's question
PC: 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. [...] There is nothing in the PhyloCode that prohibits naming a clade, some species of which belong to another non-nested clade [...]. 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)? Thus (expanding this logic to LGT cases), wouldn't it be hard to apply phylogenetic nomenclature (without running the risk of having a lot of circumscriptional changes) to the prokaryotes where so much new information on lateral (horizontal) gene transfer is being and remains to be discovered? Gerry Moore Research Taxonomist Brooklyn Botanic Garden 27 Sep. 2000