Species as "Hypotheses"

Richard Pyle deepreef at BISHOPMUSEUM.ORG
Sun Jul 11 18:10:19 CDT 2004

Thanks for the reply, Ken.

One question, and one comment:


So.....do you see assertions about species boundaries more as hypotheses
that can be tested and potentially falsified; or do you see them more as
definitions that are followed or ignored based on subjective preference by
other taxonomists?


>       That is just one reason why I am totally opposed to
> phylocode-type definitions of taxa at any level.  Freezing
> definitions during any particular time and paradigm is
> short-sighted and arrogant, although it might be somewhat less so
> 50 years from now.

For the most part, I've given up trying to argue on this list why I, as
someone who would never use the Phylocode in my own taxonomic career, can at
least understand why a multi-point definition of taxa makes MUCH more sense
if you're trying to stabilize and make objecting taxon concept
circumscriptions.  I do not know what motivates the Phylocode proponents, so
I can't comment on arrogance.  But I don't understand how you can say that
something could be short-sighted now, but less so 50 years from now.  It
seems to me that developing a system to accommodate the needs of taxonomic
definitions fifty years from now is the opposite of short-sighted.  "Ahead
of its time", perhaps.  But not short-sighted.

The way we Linnaean taxonomists define taxa is necessarily subjective (the
subjectivity being in where we draw the lines, or how we define where the
lines should be drawn, or both).  Linnaean names have a single-point anchor
(the primary type specimen).  The boat is free to drift about as the winds,
tides, and currents of taxonomic perspective change, without violating the
rules by which the name was established.  Phylocode names have two or more
anchors.  That means the boat stays fixed in space *and* time.  Granted, our
ability to identify with adequate certainty whether or not a given organism
is, for example, a descendant of the most common ancestor shared between two
other organisms, may be limited at this time in our technological progress.
But surely at least the question is one that has only one objectively
"correct" answer (ignoring lateral gene flow, rare hybridization, etc.).
Contrast that to the question, "Does this organism share a close enough
kinship with the primary type specimen of this species name to be considered
as a conspecific?"; or "Would the communicative needs of biologists be best
served by treating these two organisms as conspecific?" -- which are
essentially the questions that we Linnaean taxonomists try to answer.

Don't get me wrong -- I'll almost certainly be a practitioner (and ardent
defender) of the Linnaean nomenclatural system until the day I die.  But,
for those who are interested in establishing objective definitions for names
in a monophyletic context, a multi-anchor definition system is definitely
the way to go (whether or not that system is the Phylocode).


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