A biological continuum continued

Curtis Clark jcclark at CSUPOMONA.EDU
Fri Mar 31 12:24:56 CST 1995

Date sent: 31-MAR-1995

 >There may lie our problem.  We both see each other as being
 >altogether too dogmatic about the points we are trying to get
 >across.  The concept of bimodality (or multimodality) will
 >operate at many levels: population, subspecies, species, genus
 >(or similar artificial ranking) -- do I detect another form of

You seem to see them wherever you look.  :-)

 > Does your concept of bimodality operate through
 >multiple dimensions or is it simply a frequency at a particular
 >point in time and space.  Obviously it would be a bit
 >hypocritical to work as a taxonomist without recognizing the
 >existence of some sort of discontinuities, partial or complete,
 >somewhere.  Without meaning to criticize any reader of TAXACOM,
 >especially you Curtis, I note that it is easy to detect
 >"bimodality" using a limited number of samples.  This is not so
 >much of a problem now as it was for botanists of the last

Sometimes I feel like I'm caught between you and a straw man (if you
feel the same way, my apologies).  I have no "concept of bimodality".
My graph was bimodal.  Following accepted practice, my graph was of
a hypothetical *sample*, not the whole of biodiversity.  Remember that
it is also easy to detect "continuum" using a limited number of samples.
You seem to be implying that my samples are not rando while yours
are, but all I'm saying is that assertions of a continuum must be
based on the data, and that if you assume everything is a continuum,
you may never look.  If I had known I would be held accountable for
this, I might have measured as many features as I could conceive of for
every one of the thousands of Encelias and perhaps millions of other
organisms that I have encountered in my career (or perhaps I would
have picked a different career, such as attorney :-).  Perhaps because
I looked for modality, I found it.  But if it is truly there, at least
I looked.  As for botanists of the last century, I'm not *that* old!

 >> >Maybe the difficulty is that your work is done on California
 >> >plants (?).
 >>Cheap shot.

 >I think not, although it might seem like it.  The point is that
 >my concept of continua, as alluded to above, is one that tends to
 >consider large geographic areas

Convince a tropical botanist that the holarctic region is large.
Don't use a Mercator map to prove your point.  I apologize for my
poor genus Encelia for being distributed only from Utah to Baja
California Sur, and I am suitably humbled that my lowly position
at a state college has not afforded me the opportunity to botanize
outside North America.

 >(as well as evolutionary time --
 >did those 12 synapomorphies defining the clade arise in one

Is this flame bait, or what?  Of course not.  Why does it matter?
Frequencies of different phenotypes differ across time just as they
do across space.  And certainly there is geneological continuity among
all organisms.  But again, if you don't look for pattern, you won't
find it.

 >Well a specific example has now been alluded to (_Encelia_ in
 >California, right?), I will try to look it up, but how can I be
 >sure that it's not a special case exception?  :-)

How can either of us be certain of anything the other says? ;-)

 >   Thank God we
 >"disagree", otherwise the discussion would flounder to a rather
 >boring ending.  Thanks for the discussion Curtis!
 >Too bad everybody else on TAXACOM is ignoring this thread and
 >jabbering endlessly about ZPG, maybe it means that we are both
 >being trivial and uninteresting (if not long-winded).

I think I'm ready to drop this except through private e-mail, unless
other Taxacomers want to pick it up.

Curtis Clark                                       Voice: (909) 869-4062
Biological Sciences Department                     FAX:   (909) 869-4396
California State Polytechnic University, Pomona
Pomona CA 91768-4032                               jcclark at csupomona.edu

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