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Re: a rose by any other name(was fish & dogs)


You say "Before tetrapods evolved, fish (Pisces) was a perfectly good 
holophyletic group, and the cladists want to retroactively say it's not 
a real evolutionary group just because it's paraphyletic!?" At the risk 
of misconstruing your meaning (I have not seen the term holophyletic 
used elsewhere and don't know how it relates to monophyletic - 
definition please?), Pisces is only a real group if you consider it to 
be equivalent to Gnathostomata. Clearly, that's a bit pointless unless 
you consider yourself a fish.

You say we don't have to recognize EVERY (my emphasis) paraphyletic 
group. So who decides WHICH groups are worth recognizing? If there is 
to be any stability in nomenclature we need to follow some rules, and 
your classifications seem to be inconsistent in this department. I 
don't teach ranks to students any more because once you start placing 
them on phylogenies they quickly become highly confusing. Dinogeorge's 
example serves as well as any here. Tetrapoda is probably the sister 
taxon to one lineage of elpistostegalian fish, and few gradists would 
argue these should be of equal "rank." I think the battle between 
grades and clades was fought and won in the literature some time ago. I 
don't believe the scientific literature will go down that road again. 
Debate now focuses on issues such as node or stem-based definitions 
(see Benton's recent paper in Biological Reviews). Unless 
classification schemes reflect phylogeny we're back in the jungle, 
metaphorically speaking! I think most people would prefer to follow a 
set of rules (one rule really: only monophyletic groups are real) than 
bend to the will of the latest "authority."


Kendall Clements