Fwd: Re: rankless nomenclature

[Richard Jensen]

Phil Cantino has been very gracious and has provided clear responses to
most questions posed (he seems to be the only PhyloCode proponent doing
so).  And, I agree with him that many of the PhyloCode proposals will
provide solutions to the kinds of problems raised here.  But...

There are a couple of matters that I am not able to reconcile.  First, my
question, which Susan Farmer reiterated, still remains (at least in my
mind): When there are two competing, and quite different well-supported
(e.g., high-bootstrap and decay values) phylogenies that place the same
lower taxa in (very) different clades, how does the PhyloCode resolve this
problem?  Do these taxa exist in taxonomic limbo (I forget the name
Donoghue and others have used for such orphans) until a "better" phylogeny
comes along?  Or, does some independent party gather the data and produce
a strict (why not majority rule?) consensus?

Phil has suggested that only clades that we feel quite confident about
should be named and peer review will control this.  How is the degree of
confidence defined?  Will there be an *explicit criterion* based on a
*universally accepted measure* of stability or predictivity that will
allow all to agree on whether clade X now deserves recognition as a
legitimate taxon, or that clade Y is now placed in the dustbin of history
because new data suggest that clade Y is paraphyletic or polyphyletic?
Or, will it be a function of the consensus of those who serve as reviewers
for a particular ms. that assigns names to a series of clades when the
data disagree with earlier clades for those taxa?

I agree, to a point, with Richard Pyle.  Our current rank-based system
serves well.  When someone says Quercus or Fagaceae or Fagales or
Liliopsida, I have a really good idea of what is meant.  These names refer
to groups in which the members share many of the same characters; they are
natural groups.  Are they monophyletic groups as currently
circumscribed?  Probably, but who knows for sure?  A key here is to
provide access to information in a stable and predictive way. A rankless
classification has the same goal, except that it is designed specifically
to reflect phylogenetic relationships.  So, I suggest that Richard Pyle
consider history.

I argued, I thought, reasonably that phenetic and cladistic
classifications, which have different goals, could exist side-by-side,
simply because they are two different views of the same
information.  George Estabrook provided a view, convex phenetics,
which combined components of both approaches.  And Jim Rohlf and others
provided a way to view a cladogram in phenetic space.  But, few agreed
with my view of friendly coexistence (despite the fact that it has been
demonstrated that phenetic classifications often are more stable and just
as predictive as cladistic classifications).

Deja vu all over again!?

Dick


Richard J. Jensen      |   E-MAIL: rjensen at saintmarys.edu
Dept. of Biology       |   TELEPHONE: 219-284-4674
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