[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Why all the fuss? (flame-free)

Sorry for the long post...

> Quick answer:
>      Utility and relative stability, among other considerations.  And
> avoiding the many drawbacks (both short-term and long-term) of strictly
> cladistic classifications, which are detailed in Benton, 2000 [...]
>         http://palaeo.gly.bris.ac.uk/phylocode/biolrev.html

Sad to say I haven't read/found Mayr and Ashlock's book. Benton's article,
however, is in some places very emotional and often very personal. For
instance, Benton simply doesn't believe it's likely that people will accept
the priority of definitions when the PhyloCode is implemented and will
continue to quarrel as they do now. (Maybe they will, maybe not, we'll see,
IMHO.) This may also be a reason why he doesn't mention many of the
cautionary recommendations of the PhyloCode. I am surprised, however, that
the companion volume which will be published a while before implementation,
it is planned, and will contain lots of proposed definitions for final
discussion -- not even only to dismiss it as infeasible, too long in
production (which has already begun), useless for stopping the discussions
rather than fuelling them or suchlike, all of which are easily conceivable
objections and will surely make that work very hard. The first half of the
paper IMHO implies that many or most advocates of phylogenetic nomenclature*
call for abandonment of species as well as higher ranks; it is mentioned
that only "some" such people do that later.

* Benton does a good job of clearing up the definitions of the many terms
that are used in such discussions.

Benton uses some examples that make very weak arguments for retaining ranks:

"Biology students have to organise knowledge,"


"and they would have a hard time if they could no longer refer to lists of
phyla or classes."

If they could no longer refer to any lists, true. But people don't, after
all, agree what phyla or classes are. I learned last semester about
Nemathelminthes as a single phylum, containing Rotifera, Nematoda,
Nematomorpha etc. as classes, while all general books about them that I can
find in the biology library treat them as phyla and often don't consider
Nemathelminthes as monophyletic. That geneticists now consider it para- or
polyphyletic because it excludes Arthropoda is another issue. I also learned
about the two systems of plat(y)helminth classification (old: Cl.
Turbellaria, Cl. Trematoda, Cl. Cestoda; new: Cl. Catenulida, Cl.
Acoelomorpha, Cl. Rhabditophora which includes Neodermata which includes
Trematoda and Cestoda); we were told that the old system should not be used
because Turbellaria is so paraphyletic, but the body plans etc. were
explained using the old system nevertheless. What is in reality done to a
large extent IMHO, and what should be done IMHO, is that in such lectures
the phylogeny of animals is explained from the base to a certain arbitrary
level which finds itself somewhere around the phyla and classes of
traditional systematics. I don't have much of a problem when body plans of
e. g. "free-living plat(y)helminths" are explained (who except specialists
and taxonomists cares about Catenulida, or will ever see such an animal).
Just use the same names as ever, unless paraphyletic, and drop the ranks!
:-) The manageable list (see below) is retained that way. To abandon ranks
doesn't mean to abandon taxa.

"In learning about zoology, the list of phyla is manageable, and it is a
fundamental way of organising knowledge."

"Bird watchers rely on lists of orders and families (compare the utility of
a list of 20 orders of birds - owls, kingfishers, penguins - with an
unranked listing of 9000 species) [...]."

Nobody suggested using an unranked list of 9000 species. Simply use a
reasonable number of reasonably recognizable clades, which is IMHO the same
as many or all suggestions how to divide Neornithes into orders, and admit
that there is no order level, which is the only difference to the
traditional system.

I can't claim that the PhyloCode will bring salvation to taxonomists, but
could you, HP Ken Kinman, be more specific about the drawbacks, unless of
course you think it has all been discussed to death onlist back in 1994? :-)