Paraphyly=mistakes? (There's the rub)

Richard Pyle deepreef at BISHOPMUSEUM.ORG
Tue Jan 8 13:12:41 CST 2002

> I think it is
> essential that the scientific classification be rigorously
> aligned with our
> best inference as to the true historical branching pattern.

Yes, that much is clear based on your posts (assuming you are using
"scientific classification" synonymously with "Linnaean-style
nomenclature").  What's not clear, however, is whether there is always
wisdom in that approach.  Certainly in MOST cases, there will be close
accord between well-founded evolutionary relationships and broad
interpretation of nomenclature....but there will always be the exceptions --
the cases where morphology/behavior/ecology/etc. might influence us to use
names that do not strictly reflect the "phylogeny du joir".  Because the
current Linnaean nomenclature was created prior to the widespread
recognition of evolutionary process, it certainly wasn't *intended* to
strictly reflect phylogenetic relatedness. That it is used that way today by
many in the cladistics camp (sometimes with no small amount of contortion
and instability) does not negate the fact that many used it quite
successfully very much in conformity to science (and still do), for purposes
that go beyond the bounds of strict communication of phylogenies.  In other
words, it's not necessarily a safe assumption that "it is essential that the
scientific classification [nomenclature] be rigorously aligned with our best
inference as to the true historical branching pattern".

> Since we have
> all (I should hope) accepted the evolutionary paradigm, we should
> recognize
> that artificial groupings are not only meaningless, but downright
> deceptive
> if used (as they have been) to make biological process arguments.

Hmmm...not so sure about deceptive....and definitely dubious about
"meaningless".  There is certainly more "meaning" in biology than simply the
elucidation and short-hand communication of hypothesized phylogenies ---
shouldn't we evaluate the real reasons we find biological nomenclature a
useful endeavor before we make such broad assumptions?

> If you
> wish to analyze the dynamics of evolutionary change, of what possible use
> would it be to consider Reptilia in its paraphyletic sense? The
> evolution of
> birds has been the most interesting thing that ever happened in reptilian
> evolution - what sense could one make of this if birds are artificially
> placed in a separate category?

I hardly regard it as "artificial" that birds have feathers, can fly, etc.,
etc.; whereas reptiles do not.  If you assume that nomenclature MUST reflect
strict phylogeny, then I can certainly see how you might be misled by the
nomenclature.  My point (and I think the point of others), is that this
assumption isn't necessarily warranted in all cases.

> It seems clear to me
> that the only useful approach is to have a classification that recognizes
> real historical units, and to then map divergences on that tree.

It's not so clear to me that this represents the "only" useful approach, but
I fully agree that it represents "a" useful approach -- and an extremely
important one at that.  So important, in fact, that it deserves much more
than the contortion of a nomenclatural scheme developed a hindered years
prior to the notion of evolution.  The need to accurately communicate
phylogenetic hypotheses via nomenclature (which really boils down to the
need to communicate using text, rather than requiring graphic images of
cladograms) is so important, in my opinion, that it deserves its own
dedicated scheme -- one designed *with* an a-priori understanding of the
evolutionary process.  One that doesn't hinge so critically on stability
over time(**).  One that looks an awful lot like the Phylocode.

At any rate, I'll leave it to others to suggest scientifically valid reasons
to counter your broad-sweeping, and phylo-centric views expressed below.

I just want to be clear that what we are arguing about here is *NAMES*, and
how they are most effectively used as tools of communication -- NOT about
whether we should or should not recognize and discuss questions about
evolutionary history.


(**)Note: I don't mean to imply that Phylocode is inherently instable
insofar as nomenclature goes.  In fact, it is generally *more* stable than
Linnaean nomenclature (if for no other reason than the elimination of
binomials).  What I mean is that frequent alterations in the re-arrangement
of names against a phylogenetic context does not inherently disrupt overall
stability as much as it does in the ranked Linnaean system.

> That is an
> utterly useless scientific statement, and yet it is the best that can come
> of the Darwinian strategy. This system has been abandoned by
> scientists for
> this very reason - it may make for interesting cocktail chatter
> to know that
> Kinman thinks that taxon X deserves to be ranked as a class whereas
> DiBenedetto thinks it should only be an order - but basically who
> cares? And
> what good is it? However, to have a clear picture of what the real
> historical lineages are is profoundly important to advancing scientific
> understanding of all taxa.
> I really can't believe that we are still having this conversation in the
> twentyfirst century.
> Tom DiBenedetto

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