Andrew Grebneff wrote:

> An increasing number of workers do not recognize subspecies. If the
> "subspecies"is similar enough to typical specimens, they regard it as
> a synonym; if sufficiently and CONSISTENTLY different, as another
> species.  I follow this method.

* the problem with subspecies is that the concept was invented by
ornithologists, working with highly mobile, highly panmictic (freely
interbreeding) continental Birds. Their motive wasn't a profound
reflection on models of possible and actual intraspecific variation
among Animals with all possible modes of reproduction and dispersal, but
rather to avoid insulting their friends by completely sinking taxa the
friends had named -- the friend-described taxon remained on the books as
a subspecies even after it had been found to intergrade with previously
described forms.

The concept spread to mammalogists, after they'd gotten over the idea
that "the best distinguishing feature of a species is a hundred miles
[from a previously described form]."  Then, human nature being what it
is, the description of oodles of barely distinguishable subspecies
became a goal (sometimes, apparently, the main goal) of ornithology and
mammalogy. Workers in malacology and other invertebrate groups continued
to name varieties and forms and other infraspecific categories, but
without the clear spatial, reproductive, and evolutionary model that the
ornithologists and mammalogists had for the subspecies.

Because the ornithologists were working with the best-studied organisms,
with the simplest reproductive characteristics, and were at the
forefront of the movement to establish the Code, subspecies got embedded
in the International Code of Zoological Nomenclature, while forms and
varieties were eschewed as "too botanical" to consider.

The zoological subspecies concept assumes a testable biological species
concept: it doesn't matter how different subspecies are, genetically or
phenetically, if they interbreed where they come into geographic contact
they're the same species, and must be treated, if "taxonomically
different," as subspecies (the botanical subspecies is a different and
weirder creature altogether, with no geographic component).

Molluscs are even more unbirdlike than Plants, however. On land and in
ponds they have highly restricted mobility, often live in fragmented
habitats, and depend on chance for any long-distance dispersal that
occurs. In lakes and streams they're strictly restricted to particular
drainage systems, or obliged to hitch rides on fish. On coasts (see the
origin of this thread) they live in habitats that may be highly
distinctive on a scale of a few metres. In the sea huge areas may be
panmictic, with larvae settling hundreds or thousands of kilometres from
where the parents lived. Any marine lineage may opt out of this
basin-wide panmixia if it's advantageous to take up direct development
without a larval stage. Uniparental reproduction is often a possibility.
"Populations" with distinctive morphology and genetics can arise by
selection among larval colonists of a site without any reproduction
among them, and the morphology many species is extremely plastic in
response to habitat characteristics.

Each of these aspects of life history and population structure may make
the subspecies concept inapplicable -- even without addressing Wilson &
Brown's point that smooth clinal variation, and the resulting
"identifiability," on which the classical subspecies was based, doesn't
mean that the identifiable classes of specimens represent "real"
entities. One way of thinking of this is to ask whether classification
into groups explains more variation than a regression on environmental
or geographic variables does.

If a subspecies isn't a testable hypothesis about the reproductive
relationships of spatially grouped populations, it's hard to see what it
could be, beyond a hope that the situation could be addressed in more
birdlike terms. Wilson & Brown recommend using informal names for
discussing groups of populations below the species level, and the
usefulness of these might be increased by informal categories which
hypothesize causes for the homogeneity within the groups or the reasons
for their difference from other groups.

One problem is that there are so many thousands of species, and so many
of them would be intractable for the kind of study that could resolve
any of these questions, even if funding for study was available...

fred (who wishes he had time to study any of these questions among the
specimens he's collected)
------------------------------------------------------------
            Bishops Mills Natural History Centre
          Frederick W. Schueler & Aleta Karstad
       RR#2 Bishops Mills, Ontario, Canada K0G 1T0
    on the Smiths Falls Limestone Plain 44* 52'N 75* 42'W
      (613)258-3107 <bckcdb at istar.ca> http://pinicola.ca
------------------------------------------------------------
If we'd been meant to refer to species by made-up vernacular names,
                God wouldn't have created Linnaeus!
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