Species as "Hypotheses"

Richard Pyle deepreef at BISHOPMUSEUM.ORG
Sat Jul 10 09:01:55 CDT 2004

Greetings Taxacomers,

I spent much of this morning cleaning out old email, and have just now been
reading through the thread "A zoologist asks:  botanical names practice",
that was on this list a couple of weeks ago.  Several posts in that thread
state that a species is a "hypothesis".  I've seen this assertion repeatedly
on this list and elsewhere, and for the life of me I cannot figure out what
the statement is supposed to mean.  Maybe this question has been asked &
answered many times before on this list (and elsewhere), but if so, it
hasn't burned itself into my non-volatile RAM.

So...when one says that a species is an hypothesis, what, exactly, is the
hypothesis?  How would one falsify this hypothesis?  What would be the
corresponding null hypothesis? Could this hypothesis ever mature into a
full-blown "theory"? (e.g., maybe Homo sapiens has achieved the status of
theory, whereas, say, Centropyge fisheri is still just an hypothesis?)

Clearly, "species" in the nomenclatural context are not hypotheses (I'm not
aware of any articles in the Codes of nomenclature that address hypotheses).
So I have to assume that the "hypothesis" has something to do with species
as concepts (circumscriptions).

But even in that context, I see them as definitions: "I define the concept
of Centropyge fisheri to include all individuals having thus & such set of
character states" (traditional species concept definition); or: "I define
the concept of Centropyge fisheri to include all descendants of the earliest
ancestor of the holotype specimen of that name, that is not also an ancestor
of the holotype specimens of C. acanthops, C. argi, C. aurantonotus, or C.
resplendens" (sort of a PhyloCode definition of a species concept).  If
either of these were treated as hypotheses, how would you go about
disproving them?  Mustn't hypotheses be falsifiable in order to be
considered scientific?

It seems to me that the only way it could be falsifiable is if we had an
objective definition for "species"; and demonstrating that two individual
organisms fall within the threshold of such an objective species definition
would falsify the hypothesis that they belong to different species.  But we
do not yet have such an objective definition in wide-spread (or even
narrow-spread) use.  Until we do, I can't understand how we can treat a
"species" as an "hypothesis".

Confused in Kaneohe.....


Richard L. Pyle, PhD
Natural Sciences Database Coordinator, Bishop Museum
1525 Bernice St., Honolulu, HI 96817
Ph: (808)848-4115, Fax: (808)847-8252
email: deepreef at bishopmuseum.org

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