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On Sun, Apr 13, 2008 at 10:28 PM, evelyn sobielski <email@example.com> wrote:
> > Arbitrary
> > ranks like
> > "Order", "Family", etc. are not necessary (or, IMHO,
> > particularly
> > useful).
> If they are used to denote major shifts in ecological
> niche/ecomorphology, they are not arbitrary
They are still arbitrary, unless you can come up with some discrete
metric of ecological change and correlate this metric to ranks.
> and actually quite useful - as they will then also denote
> a major shift in *how* evolution acts upon a lineage.
It seems to me there are already plenty of far better ways to discuss
this without bringing Linnaean ranks into the mix.
> The problem of paraphyly remains, namely at very high
> and very low ranks. The former can be solved by a
> phylogenetic nomenclature; the latter... well...
I think phylogenetic nomenclature can solve this sort of problem, too,
if we recognize that clades are not the only possible type of
phylogeny-based taxon. They are one of the most salient and useful
types, and there are certainly the best-established type, but who
knows what the future may bring for phylogenetic nomenclature?
(Incidentally, it's not immediately obvious to me that clades aren't
enough here--as long as clades are considered sets of organisms, not
sets of taxa. I'll continue to look at these refs, though--thanks for
T. Michael Keesey
Director of Technology
2894 Rowena Avenue Ste. B
Los Angeles, California 90039