Message 2001-02-0061: Fwd: Re: Codes

Mon, 12 Feb 2001 15:25:24 -0500

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Date: Mon, 12 Feb 2001 15:25:24 -0500
From: Philip Cantino <>
Subject: Fwd: Re: Codes

I will respond to some of David's comments in his recent postings.

David wrote:

>Now I have the rest of Gerry Moore's message. All I can say is that
>his experiences are very different than mine. The only objections I
>hear when I explain the PhyloCode are from people who worry about
>the possibility of two competing, parallel systems of nomenclature
>(a point to which I fully agree). I cannot believe that anyone wants
>that...two different names for everything, and no one able to
>understand the other side.

We seem to have different understandings of what is meant by
"parallel systems."  I certainly don't advocate having two different
names for clades.  As you know, I favor designating PhyloCode names
with a symbol (a "value-added symbol", if you will), but the name
would not differ in any other way from the name applied to that taxon
under the traditional system.  Furthermore, I accept the majority
view of the advisory group that the symbol will not be mandatory.  So
at this point, I don't think that we have a disagreement about this
issue.  When Gerry and I refer to parallel systems, we mean that the
names are defined in a different way, not that the names themselves

Gerry wrote:
>The only other point that I didn't already respond to was:
>>Hillis was critical of the existing system, noting that it required
>>"diagnoses of taxa rather than phylogenetic definitions, and the
>>diagnoses don't even have to be correct." However under the
>>PhyloCode one can define taxon names under a phylogenetic
>>hyopthesis that is also later proven incorrect.

David wrote:

>The difference is that the diagnosis doesn't have any required
>connection to the name under the existing codes, so even if the
>diagnosis is accurate, someone else is free to apply the name to a
>group that doesn't fit the diagnosis. There has to be a diagnosis,
>but it doesn't have to be correct, and it doesn't carry any weight
>in assigning the name to a group of organisms. That decision is
>entirely subjective, as long as the group contains the type species.
>Under the PhyloCode, the definitions are formulated in such a way
>that they unambiguously apply to a single clade in the Tree of Life.
>Our understanding of phylogeny may change, but the definition always
>points to a single, unambiguous clade, no matter what the
>phylogenetic hypothesis may be.

True, but the content of that clade will vary depending on the
phylogenetic hypothesis, which was Gerry's point.

In another message, David wrote:

>Group names are not defined at all in the old codes, which is why
>they can be applied by anyone in any way they see fit, as long as
>they contain the type species for the group.

Group names are defined in the old codes, at least operationally, in
terms of a rank and a type.  For example, Asteraceae is defined as
the taxon of family rank that includes the type of Aster.

>The new system does indeed remove this "flexibility" (in other
>words, subjectivity) by adding objective definitions to group names.
>I'm arguing to keep the system basically the same, but remove the
>subjectivity by linking the names to evolutionary history (in other
>words, to real historical groups).

I think you and I are arguing for exactly the same thing, but you
view the difference between the two systems as merely an "upgrade",
whereas I agree with Gerry that the difference is more fundamental.
We are of course each free to view the difference however we want to,
but the way you describe our differences, it may sound to some as
though we are actually advocating different systems, which I don't
think is the case.  We both basically favor the rules for clade names
embodied in the draft PhyloCode.

>I do not know what the eventual convention that adopts the PhyloCode
>will choose to do. I do know that if the convention were to adopt a
>set of rules that forced me to make separate descriptions for taxa
>under the old and new codes (thus creating parallel and competing
>taxonomies), I would no longer have any interest in participating.

Here and elsewhere, you refer to separate descriptions.  I don't
think anyone is suggesting that there be separate descriptions for
taxa under the two systems.  Providing a description is a different
process than defining the name.  I would hope that a description
would be provided under either system when a name is published, and
there is no reason why it shouldn't be exactly the same description.

In yet another message, David wrote:

>Many (the vast majority in my experience, although I realize that I
>have a biased sample) systematists reject paraphyletic groups now,
>and only use names that have been given to paraphyletic groups if
>the group concept is changed to include all the descendants of the
>common ancestor. That is the same under the old and new codes. I
>can't remember the last time I heard of someone purposefully
>supporting the naming or recognition of a paraphyletic group.

I think that zoologists (at least vertebrate zoologists) are ahead of
other systematists in this regard.  I'm sorry to say there is still
widespread support for paraphyletic groups among plant taxonomists.
I still (frequently!) find myself having to defend my rejection of
paraphyletic groups.  Perhaps some of the difference in our
perspectives stems from this difference in our disciplines.  I wonder
how invertebrate zoologists stand on this issue.  Anyone care to

>Under Method M (and only under Method M among the Cantino et al.
>methods), the same species description can meet the requirements of
>both the old and new codes.

"Description" again.  The same species description can and should be
provided under both systems no matter which naming method is used.
Where we differ is the form of the name, not whether or not the
description is the same.

A bigger question that hasn't been addressed at all, though, is how
species names will be defined under the PhyloCode.  Will they have a
phylogenetic definition like clade names do and, if so, what form
will it take?  This, as well as the form that species names should
take, will have to be resolved before rules for species can be added
to the PhyloCode.  The Cantino et al. paper considered only the form
of species names, not the issue of definition.

>Under Phil's preferred system, a description under the new rules
>would not fit the old rules, so one would either have to only
>describe  species under one set of rules, or publish two
>descriptions for the same species (one under each set of rules).

Nonsense!  All one would have to do is provide a single description
(mandatory under the current codes; optional under the PhyloCode),
presumably define the name phylogenetically (if required under the
PhyloCode--this issue has not been resolved), provide the PhyloCode
registration number, and cite the name in the two slightly different
forms required by the two codes.  For example:

Hypotheticus novus (ICBN)
Hypotheticus-novus (PhyloCode)
Phylogenetic definition:........
Type specimen:....... [this presumably will be cited as part of the
definition anyway]
Registration Number:....

How would this be done under David's Method M?  Almost identically:

Hypotheticus novus (ICBN)
novus (PhyloCode)
Phylogenetic definition:........
Type specimen:.......
Registration Number:.....

There are various pros and cons to both Method M and Method B, but
the distinction that David made in this message is a red herring.
Both methods provide a name that differs in form from a Linnaean
binomial, and neither method requires two descriptions.

David will argue that in Method M, the combination of the PhyloCode
name and a taxonomic address looks identical to the Linnaean binomial
for that species.  This is true, but there is no requirement that a
taxonomic address be cited or, if one is cited, that it be the genus
name of the Linnaean binomial.  If Quercus alba is converted to alba
under Method M, the name is alba.  Period.  Sensible people will
frequently include the taxonomic address Quercus before the name, but
there is nothing to stop people from referring to this species solely
by its name (alba) or from including some other taxonomic address
such as Fagaceae--another clade to which this species belongs.  It is
therefore misleading to argue that under Method M, the name is the
same under both codes.


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

Phone: (740) 593-1128; 593-1126
Fax: (740) 593-1130


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