rankless nomenclature

[Doug Yanega]

Barry Roth wrote:

> The frequency of new, far-reaching taxonomic revisions may increase in
>the future because new data sets are coming in fast and software for
>estimating relationsh
>ips that lead users to taxonomic changes is widely available.  Does the
>rate of name changes need to accelerate also?

I believe you're overlooking how rankless nomenclature works at higher
levels. We were paid a visit here at UCR a year ago by one proponent and he
pointed out that names used for higher ranks in traditional nomenclature
may persist in a rankless taxonomy, but they require explicit definition.
Once defined, they may not be REdefined - this, he said, gives greater
stability compared to the Linnaean approach.
        For example, under the present system, if we agree with the most
robust-looking analyses, the Rhopalocera make the Geometroidea a
paraphyletic group (in other words, butterflies are one of the descendant
clades within the superfamily Geometroidea, and their *exclusion* is
phylogenetically inappropriate), and we should simply include them, and
redefine Geometroidea accordingly. People will just have to accommodate the
new classification, and get in the habit of thinking that way. This exact
sort of thing has happened repeatedly in other groups of insects and other
animals, and people have adapted. Ultimately, the name persists
("Geometroidea" in this case), but its meaning changes. Nothing new here,
right?
        Under a rankless system, we were told, we would permanently DEFINE
"Geometroidea" as "the clade consisting of Apoprogonidae + Axiidae +
Callidulidae + Cyclidiidae + Drepanidae + Epicopeiidae + Epiplemidae +
Geometridae + Pterothysanidae + Sematuridae + Thyatiridae + Uraniidae" (our
present classification), and if someone comes along and subsequently
insists that we shoehorn the Rhopalocera in there (where they belong,
really), then they have to create a *new* name for the new group thus
created. Likewise if one of the present constituent taxa is removed.
Ultimately, in this case, the meaning of the name "Geometroidea" is not
changed, but the name becomes effectively superfluous and goes out of
circulation (since the group it describes proves not to be a natural group,
so no one is likely to ever desire to use it again), while a new name is
created to take its place, and everyone has to learn the new name. This is
apparently what rankless advocates (at least the one I encountered)
consider to be "greater stability". Come again?
        To me, it looks exactly like the proverbial "six of one, half a
dozen of the other". In what way is the creation of new replacement names
EVERY TIME a different phylogeny is published more stable than redefining
the old names every time? Either way, something changes and we are all
forced to re-learn the classification. Well, DUH! Frankly, I find it easier
to keep track of new definitions than to keep track of ever-growing lists
of new versus defunct names. Think of it this way: if rankless proponents
have their way, then it is virtually inevitable, like the workings of a
ratchet, that all the old rank names will get wiped away one by one and
replaced, so we won't have things like "Papilionidae", "Nymphalidae",
"Lycaenidae", etc. to talk about any more. I don't see that sort of
incessant, inevitable turnover of names as an improvement. To rephrase your
own question, "Does the rate of name replacements need to accelerate
also?".
        If this is what rankless taxonomy entails, I don't think it's
solving any problems for us. One final point: even if this is only that one
person's idea of how rankless taxonomy should work, rankless systems still
do allow - even encourage, in a way - the application of names to *any*
node in one's cladogram that one wishes to discuss. Unless my math is off,
if you have N taxa, they will be supported by N-1 nodes (barring
polytomies); that means that you can nearly double the number of taxon
names, if you name each node. Maybe no one would go quite that far, but it
certainly does nothing to encourage people to be *conservative* about
creating new groupings, while under the Linnaean system, there aren't
enough ranks to go around (at least from an entomologist's perspective). I
can just imagine what would happen to our present insect genera that
contain 500 or more species, for example. Can you say "open the
floodgates"?

Peace,


Doug Yanega        Dept. of Entomology         Entomology Research Museum
Univ. of California - Riverside, Riverside, CA 92521
phone: (909) 787-4315 (standard disclaimer: opinions are mine, not UCR's)
           http://entmuseum9.ucr.edu/staff/yanega.html
  "There are some enterprises in which a careful disorderliness
        is the true method" - Herman Melville, Moby Dick, Chap. 82