[Taxacom] Phylocode vs Linnean nomenclature, again.

[David Campbell]

Phylogenetic information is best displayed with a tree.  Any
nomenclatural system will get awkward if you try to exhaustively
express phylogenetic patterns, far worse than the number of names if
some paraphyletic or monotypic names are allowed, though not
mandatory.

Phylogenetic names are no more stable than traditional names, because
people using either approach are just as prone to make a bunch of new
names (or lump a bunch of existing names) on the strength of their
latest analysis.  To an outsider, it seems as if every conceivable
clade of dinosaurs has a name, for example.

Aiming for monophyly as a desirable feature of names makes sense.

Ranks are useful because they give an outsider some clue as to what
level of differentiation is present.  A monotypic higher taxon tells
you that the group is depauperate in diversity (morphological and/or
taxonomic) compared with similar taxa.  Ranks also help restrict the
potential instability caused by certain cladistic interpretations of
existing names.  If a taxon is defined as the smallest clade that
includes all the taxa included in the original publication, much
historical nomenclature will be wildly messed up.  Linnean genera, for
example, sometimes include multiple phyla.  Nautilus included not only
species from distant groups of cephalopods, but also a gastropod and
forams.  It would thus include most of Eukaryota.  But restricting it
to be a genus allows it to refer to a particular small group of
cephalopods.

The fundamental purpose of taxonomic names is to tell us what organism
someone is talking about, not to tell us its phylogeny.  Phylogenetic
information is great, but not if I can't tell what organisms it refers
to.

-- 
Dr. David Campbell
The Paleontological Research Institution
1259 Trumansburg Road
Ithaca NY 14850