Dear Tom and all

Perhaps one possible way to move forward with species problems is to go from
simple to more complicated: first agree on species definition from a
conchological point of view and after that to think about more complicated
biological aspects of the problem. In such a way we can at least gather
facts and understand better what we are talking about. I do not think that
number of species and subspecies "depends on your personal approach to
taxonomy and the purposes and methodologies of distinguishing between one
species and another." We need definitions of taxa, which are more or less in
consensus and understandable to most of us.

Because many members of this forum are shell collectors, I suggest to this
List to start a discussion in order to work out at least  primitive
(conchological) species and subspecies definitions.

Eduard Heiman

----- Original Message -----
From: "Thomas E. Eichhorst" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, July 07, 2004 7:45 PM
Subject: Re: Ernst Mayr


> Thanks John, that was a great read!  Mayr's definition of species is one
of
> many useful concepts he originated.  "A species is a group of actually or
> potentially interbreeding natural populations reproductively isolated from
> other such populations."   Of course, the kicker is that "reproductively
> isolated" part.  Thus the small green nerite, Smaragdia viridis, found in
> the Caribbean and the Mediterranean could be separated into two species
(of
> course the literature is still fighting over subspecies status).  The two
> populations are sufficiently visibly different to enable almost anyone to
> separate them and the populations are reproductively isolated.  They may
> have interbred at one time (maybe around the Miocene), but the veligers
are
> no longer able to make the transatlantic journey.  If one believes in
> natural selection and speciation, then these two populations have been on
> that track for quite some time.  The question is where/when do we draw the
> line and say, "Okay, you are now two different species."
>
> Perhaps Mayr's greatest contribution is that he sees this "grayness" to
> biology and does not believe we can finitely quantify this science with
> numbers.  Thus statistical analysis and cladograms are eminently useful
> tools, but they are only tools, part of a larger equation that also relies
> upon field and lab observation and research.  The numbers can "prove" a
> close relationship between a clam and an echinoderm - but our eyes and
> experience tell us this is patently ridiculous.  A cladogram does very
well
> at pointing out possible and probable ancestral relationships, but falls
> short when used for classification of living species - even though it so
> often looks like it does just that.  Similarly, a statistical analysis of
> dimension, tooth count, weight, etc. between shells is an useful tool as
> long as one never believes this is the final answer.  It can demonstrate
the
> bell curve of variation within a population but I believe will always fall
> short of differentiating species.
>
> All of the above is a layman's opinion and I am in way over my head, but
> always enjoy a good argument.
>
> Tom Eichhorst in New Mexico, USA
>
> > -----Original Message-----
> > From: Conchologists of America List [mailto:[log in to unmask]]On
> > Behalf Of John Wolff
> > Sent: Wednesday, July 07, 2004 7:20 AM
> > To: [log in to unmask]
> > Subject: Ernst Mayr
> >
> >
> > July 5 was the 100th birthday of eminent biologist Ernst Mayr.
> > He made major contributions to the concept of species.
> > A summary of his accomplishments and an interview of this remarkable
> > scientist done 5 years ago is available at
> > http://www.skeptic.com/eskeptic07-05-04.html
> >
> > John
> >
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