Conchlers all,

I wondered how long this string would go along before someone said, as
someone always does, "a couple of the more senior conchologist(s)
(should) get together and try to resolve this, find a solution".
Defining species is like nailing jelly to a tree. The species concept
is binary - either it IS this species or it ISN'T - but Nature is
massively complex and does not often work by rules that give binary
results. The concept of the species, however it is currently defined,
cannot resolve everything. It's a convenient way of denoting obvious
separations - Conus marmoreus is not the same as C. bengalensis, for
example - but as we all know, there are many cases in which the
differences are fine enough that it could go either way. In those cases,
there is still no single species concept that works every time, advances
in DNA analysis notwithstanding.
In wishing for some universal truth-defining process, we highlight one
of the differences between science and religion. It would be easy if we
could call upon some senior clergy, whom we trust because of their age
and the length of their beards, to get together and resolve each species
definitively and for all time. These Councils would then publish Edicts,
and that would be that - no need for anyone to think about that problem
again. That, however, is not science. The scientist - at whatever level,
amateur or pro - delights in diversity and variety, and does not treat a
problem such as the inability to define a species as some kind of
affront to human omniscience.

PC.

Paul Callomon
Collections Manager
Malacology, Invertebrate Paleontology and General Invertebrates
Department of Malacology
Academy of Natural Sciences
1900 Parkway, Philadelphia PA 19103-1195, USA
Tel 215-405-5096
Fax 215-299-1170
Secretary, American Malacological Society
On the web at www.malacological.org

>>> George Fernandz <[log in to unmask]> 5/7/2007 7:28 am >>>
Dear Bob, Ed Richard & All,
I imagine everyone at this point would like to see somehting done
about
clearing the smoke on this. By popular demand and like I mentioned,
give the
older generation of scientist their due. Give them a break
ICNZ should not be blamed for this this either. From what I heard they
are
undermaned, skelaton staff with a huge workload, that will take decades
to
complete.
My suggestion is for a couple of the more senior conchologist, get
together
and try to resolve this, find a solution. The problem can only get
worse.
not better.
Like I stated in my email yesterday. This Form of a species is all
around
us, wether we collectors, museum's, dealers are aware of the problem or
not.
The problem's here to stay and can only get worse.

Bob and Ed, made very good points and should be considered. in their
emails
below, Isolation, genetic changes, under sea ridges, and I believe
Richard
Goldberg & Mike Severns published an artical on " Isolation &
Evolution" on
this topic.

George


>MessageHello Bob,
>There are several theories of speciation. We usually consider that
new
>species evolve from the existing species after one or several
populations
>of a species become separated from the mother species by different
reasons.
>Very simplified, a long process of speciation consists of genetic
changes
>in the separated population, which were hardly possible before its
>separation because these changes (mutation etc.) were neutralized by
>interbreeding. Separation may have different forms: in land snails
there
>may be different barriers (mountains, new cities etc); in marine
molluscs
>geographical isolation is simple to prove. Isolation by different
depth is
>also works but it is difficult to prove. How can one prove that
molluscs
>inhabiting water at 30 m depth are really isolated from other molluscs
of
>the same species living in shallow water? Where is a barrier? At -25,
50,
>70, 140 m?
>After separation is demonstrated, the second criterion should be
checked:
>whether the majority of molluscs in a population differs by some
shell
>character from other populations of the same species. For example,
people
>often say that cowries from deep water are more globose; all
specimens?
>which percentage? I have never seen
>statistical data confirming this.
>Ed
>
>
>
>   I've enjoyed this thread. Eduard, your explanation is very clear.
Though
>I've often wondered about this. Why is it so important to place
emphasis
>upon geographic separation? Isn't it possible to have a population
that
>meets all criteria for a subspecies except it is separated another
way
>(such as depth) while sharing essentially the same geographic range of
the
>species?
>
>   Maybe this is a stretch on my part but it seems conceivable. If not
a
>subspecies (or a form), what would this population be?
>
>   Cheers,
>   Bob

>
>
>     Dear all,
>     It is usually accepted that subspecies are geographically
separated
>population of the same species; in other words two or more subspecies
>cannot be recognized in the same geographical area. Subspecies must
differ
>from other populations of the same species by at least one diagnostic
shell
>characteristic. This means that the majority of specimens of a
subspecies
>(about 70%) differ by certain shell character from other populations
of the
>same species.
>
>     Logically, this means that an author of a description of a
subspecies
>must prove that, first, a new taxon is a population inhabiting certain
are;
>second, that this population is geographically separated from other
>populations of the same species; third, that a new subspecies differs
by at
>least one substantial statistical shell characteristic from other
>populations of the same species. Statistical shell characteristics
must be
>calculated after examining large batches of shells. It is hardly
correct to
>describe a new subspecies after examining of 3-4 and even 20
sporadically
>found shells. If diagnostic characteristics are given in a description
of a
>new subspecies its separating presents lesser problems in the future.
>
>
>
>     Forms are regularly found unusual shells differing from
"typical"
>shells of a population in shape, color, pattern or other characters.
Forms
>are sporadically or regularly found in different populations of a
species
>and sometimes can be found in large numbers. Unlike subspecies,
several
>different forms of a single species can be found together in the same
>locality and may comprise a considerable part of that population; they
may
>not be separated geographically.
>
>     Knowing forms is not only interesting to collectors; each bit of
>information about mollusc may be useful if this information is correct
and
>published properly.
>
>     Ed

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