[Taxacom] Drosophila melanogaster name change?

Richard Pyle deepreef at bishopmuseum.org
Tue Apr 13 13:45:20 CDT 2010

> Yeah, phylogenetic trees are just that, a diagram of relatedness...

Well....*hypothesized* relatedness, at least (depending, I guess, on how one
defines "relatedness").

> And here we arrive at the question, what characteristics do 
> we use to determine whether two clades are a single taxon or 
> multiple taxa. 

More fundamentally, we (i.e., biologists) have not yet decided exactly what
information we intend to convey by applying scientific (Linnaean, anyway)
names to clusters of organisms. The names only exist to facilitate
communication, so we really ought to have a sense of what it is we intend to
communicate.  The amazing thing, in my mind, is how much we actually *agree*
on that question.  The intense passion of the debate mostly boils down to
the question of how to deal with cases involving very cohesive (in terms of
derived morphology/ecology/etc.) but anomalous paraphyletic clusters of
organisms that nest (phylogenetically) within a broader cluster of otherwise
consistent ancestral forms.  At one end of the spectrum, we have biologists
who think that 99% of nomenclature should reflect strict (hypothesized)
holophyletic patterns.  At the other end of the spectrum we have biologists
who think that 100% of nomenclature should reflect strict (hypothesized)
holophyletic patterns.  The arguments are really about the 1% of exceptions
-- not a very broad spectrum, really.

OK, I made up the 99% vs. 100% discrepancy for purposes of drama -- but the
real numbers are probably not too much different.

> For most of history, we assumed that 
> phenotypic differences mirrored genetic differences, but we 
> realize more and more that this is not necessarily the case. 
> So, we end up with the situation that we have to decide how 
> to determine what are different taxa and what are not.

This is also an issue (aka, morphology vs. molecular), but I don't see it as
being as divisive.  We use morphology (in addtion to molecules) because we
don't yet fully understand how to interpret "true" phylogeny from molecules.
Morphology has proven to be a very useful surrogate for
inferring/hypothesizing phylogenetic relationships in most cases.


Richard L. Pyle, PhD
Database Coordinator for Natural Sciences
  and Associate Zoologist in Ichthyology
Department of Natural Sciences, 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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