Date: Fri, 19 Jun 1998 09:30:00 From: SCHLAUER@chemie.uni-wuerzburg.de To: cp@opus.hpl.hp.com Message-Id: <aabcdefg2103$foo@default> Subject: Re: More on ... (long!)
Dear Michael,
> Stuessy's _Plant Taxonomy_ is a text which offers a modern (well, 1990) set
> of guidelines (yes, not rules as such) about these matters (the ICBN does
> not). Stuessy's book is not the only such text. If you are prefer other
> text(s) dealing with these issues, help educate us by elaborating!
The following two pieces are IMHO rather illustrative and fun reading
for all interested in the classification and naming of things.
I recommend:
Hamilton, C.W. & Reichard, S.H. (1992) Current Practice in the
Use of Subspecies Variety and Forma in the Classification of Wild
Plants, Taxon 41: 485-498.
Abstract: "Infraspecific classification of plants continues to be
practiced commonly by taxonomists: c. 8% of species monographed in 26
major journals and series during the period 1987-1990 were
subdivided. Of those, c. 42% were divided into subspecies only, 52%
into varieties, 3% into formae, and 3% into taxa of more than one
level. Subspecies and varieties are usually defined as requiring
some integrity - geographic, ecologic, and/or phylogenetic-beyond
the morphological.
Despite some attempts to differentiate between subspecies and
variety, they are largely equivalent in practice. European taxonomists
tend to favor subspecies, whereas their counterparts in the United
States usually employ variety. Formae usually are defined as lacking
any extramorphological integrity. Given the general inconsistency
of practice found, it is imperative that more authors state briefly
their philosophy of infraspecific taxonomoy so their classification
may be interpreted more clearly. Taxonomists collectively should
promote greater standardization of intraspecific classification."
and
Luckow, M. (1995) Species Concepts: Assumptions, Methods, and
Applications, Systematic Botany 20: 589-605.
Abstract: "The assumptions, methods, and applications of various
species concepts prevalent in systematics are reviewed in order to
clarify issues and terminology. Species concepts are classified as
mechanistic - species as participants in the process of speciation,
or historical - species as the end results of processes. Mechanistic
concepts lack universality and testability because they rely on a
knowledge of how speciation proceeded in any particular case.
Historical species concepts are preferred because they can be
consistently applied and provide a context in which processes of
speciation can be investigated.
Three historical species concepts are compared: the Genealogical
Species Concept, the Species As Taxa Concept, and the Phylogenetic
Species Concept. The Genealogical Species Concept supports the
recognition of the smallest monophyletic lineages (those that occur
at the boundary between reticulating and hierarchical systems of
relationship), whereas under the Species As Taxa Concept, hierarchy
is considered to occur below the level of species, and any
monophyletic unit may be recognized as a species. The problems
presented by applying the term monophyly to reticulating systems are
discussed as they apply to each concept, as are several problems
specific to the Genealogical Species Concept, such as metaspecies. An
alternative to monophyletic species concepts is the Phylogenetic
Species Concept, in which the smallest diagnosable unit is recognized
as a species. Monophyly is not considered demonstrable at the species
level because, in contrast to Species As Taxa, an assumption of the
Phylogenetic Species Concept is that species are basal taxa, and thus
mark the level at which hierarchic relationships begin.
Finally, the application of species concepts is reviewed by
surveying the literature in Systematic Botany and Systematic
Zoology/Biology during the past five years. Papers in Systematic
Zoology/Biology were generally more explicit about the species
concept and the criteria being used to delimit species than were
papers in Systematic Botany. Because it is clear that a number of
different concepts are currently in use, and these are often
distinguished only vaguely, botanists are encouraged to familiarize
themselves with the various concepts, and to state explicitly which
concepts and criteria are being employed in recognizing species."
I would classify the latter as a classification classification
paper. This was, therefore a classification classification
classification statement. The last sentence was...
> It is
> important for CP hobbyists to know that botanists HAVE dealt with the
> tricky issues of how to define species, varieties, etc. and have
> constucted, published, made available, some general guidelines for
> researchers.
It is likewise important to point out that botanists DO (at least
sometimes) also bother with plants.
> I believe that circumscription of taxa is a matter of interpretation,
> rather than opinion or "taste". Interpretation requires data. Opinions
> and taste do not require data (and IMHO more often refer to the practice of
> favoring aesthetics over data! :-)
It is frequently surprising how many data can be found to support a
given opinion to make it appear as a purely objective interpretation
of these data. This does not only apply to botany.
Kind regards
Jan
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