Farewell to Species

[Hubert Turner]

On 31 january, 18:02, P. F. Stevens wrote

>Names are for communication, and whatever
>system of naming/philosophy of systematics one follows, one will, I think,
>have to accept that a major element of convention informs the
>cirumscription of the particular chunks of nature that one refers to in
>general conversation and teaching.

I agree wholeheartedly!!

>From a phylogenetic perspective, given
>the ever increasing number of monophyletic groups that could be named - and
>with which almost any conceivable development of the Linnaean hierarchy in
>terms of proliferation of ranks will be unable to cope -  this is necessary
>if we are to understand each other readily.

Again, I agree. To me, the purpose of nomenclature has to do
with communicating about items in nature that have characters in
common, be they apomorphies (the only characters phylogeneticists
would want to use) or plesiomorphies (which are also taken into
account by traditional taxonomists). Group names in nomenclature
might designate clades (monophyletic groups), or grades (paraphyletic
groups). That a group is recognised (and named) on the basis of
symplesiomorphies is irrelevant, as long as the recognition of the
group is useful in some context  (e.g. reptiles - a grade: all
air-breathing [plesiomorphic at this level] vertebrates [ples] that
lay eggs [ples] outside water [apomorphic at this level], are
cold-blooded [ples] and have a scaly epidermal coverage [apo?
(reversal?) but with further apo. states to follow]).
"Reptiles" is obviously a useful name for a group of
organisms, and as such even worthy of a taxonomic name, but
phylogenetically, "what, if anything, is a reptil"?
My conclusion is that (traditional) nomenclature and
phylogenetic systematics are two different things, each with its own
purpose, and almost by definition not compatible. If they were to be
made such, useful properties of at least one of the systems would be
lost.
For me, it is fully acceptable that nomenclature does not follow
phylogenetic structure. However, people should be made aware that the
two are different systems, and that "reptiles" have no
place in a comparitive study between the different clades of
vertebrates. The only thing that nomenclature should adopt from
phylogenetic studies, is the avoidance of polyphyletic groups, but
that has been the practice ever since evolutionary thought was
accepted.


Hubert Turner


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Dr. Hubert Turner
EEW, Sect. Theoretical Biology & Phylogenetics
PO Box 9516, 2300 RA  Leiden, The Netherlands
Visiting address: Van der Klaauw Laboratory, Kaiserstraat 63, Leiden
Phone: +31-71-5274904    Fax: +31-71-5274900
E-mail: turner at rulsfb.leidenuniv.nl
WWW: http://wwwbio.leidenuniv.nl/~turner/index.html

FROM 18 JANUARY TILL MID-APRIL I WILL BE VISITING THE NEW YORK
BOTANICAL GARDEN AS VISITING SCHOLAR, DOING MOLECULAR
PHYLOGENETIC RESEARCH ON ANACARDIACEAE. THIS E-MAIL ADDRESS
WILL REMAIN FUNCTIONAL DURING THAT PERIOD.
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