Fwd: Re: rankless nomenclature

[Philip Cantino]

Dick Jensen wrote:

>I wonder how the PhyloCode establishes priority?  Suppose two
>different labs have developed competing phylogenies for the same group of
>taxa.  Each lab publishes a well-supported phylogeny based on the data
>they have used (could be morphological vs. cpDNA, cpDNA vs. mtDNA, mtDNA
>vs. nDNA, etc.) and each publishes a series of clade names to reflect
>their understanding of relationships among these taxa.  How does one
>decide which classification is considered "correct"?  Or, is each
>classification viewed as a working hypothesis and all the names are given
>some sort of temporary status?  Maybe there is a way to construct a
>consensus of the two classifications and choose clade names based on which
>clades (if any) from each classification are preserved.
>


The PhyloCode does not attempt to determine which classification or
phylogeny is correct.  It deals entirely with the application of
names.  When homonyms and synonyms exist, the PhyloCode relies on
priority of publication to select the correct name for a taxon, just
as the other codes to.  The first name published for a clade has
precedence over subsequent names for the same clade (synonyms), and
the first definition published for a name has precedence over
subsequent definitions for the same name (homonyms).  As under the
other codes, a governing committee has the authority to conserve
later names or definitions over earlier ones if a convincing case can
be made that doing so would be in the interest of nomenclatural
stability.

The situation you describe may not arise anyway if people follow the
recommendations of the PhyloCode.  As I pointed out in an earlier
message today, the PhyloCode discourages publishing names for poorly
supported clades, and the requirement for peer review will help to
enforce this recommendation.  It would be best not to name clades for
which there is conflicting data.  One could decide to name only those
clades that occur in the strict consensus tree or that have greater
than a certain level of support (e.g, bootstrap values) in all
analyses.

I hope this helps clarify things.

Phil



Philip D. Cantino
Professor and Chair
Department of Environmental and Plant Biology
Ohio University
Athens, OH 45701-2979
U.S.A.

Phone: (740) 593-1128; 593-1126
Fax: (740) 593-1130
e-mail: cantino at ohio.edu