[CPN] definition of taxon

    Cantino, Philip cantino at ohio.edu
    Tue Feb 26 15:11:27 EST 2013 
    Dick,

Regarding your objection to the proposed definition of "taxon", the wording we have proposed is more consistent with the zoological perspective than the botanical one.  The ICZN glossary defines taxon as "a taxonomic unit, whether named or not".  In contrast, the botanical code defines a taxon as "a taxonomic group at any rank".  Since rank is not assigned to a group unless it is named, the ICBN definition implies that a group of organisms is not a taxon unless it is named.  So you have not been misusing the term "taxon" in the context of plant systematics.  However, the PhyloCode needs to serve the systematics community as a whole.  From this perspective, I think the ICZN definition is preferable because it is broader; it encompasses the ICBN concept of a taxon, whereas the latter does not encompass the former.

Phil


On Feb 26, 2013, at 2:46 PM, Richard Olmstead wrote:

I'm afraid I've reached the point where I'll approve virtually anything in order to get this thing done and out.

So, I'll vote to approve the suggested changes.

That said, I have an objection that may simply reflect my misuse of the term "taxon" for, oh, say, my whole career.

Here is the proposed change:

Current
1.1. The groups of organisms whose names are governed by this code are called taxa (singular: taxon). Taxa may be clades or species, but only clade names are governed by this code.
Proposed
1.1. The groups of organisms or species considered potential recipients of scientific names are called taxa (singular: taxon). The only taxa whose names are governed by this code are clades.  However, species, whose names are governed by the traditional codes, are used to define clade names in this code.
In my mind, a clade is a clade, whether anyone names it, or even knows it exists.  BUT, a clade, or any other entity (species, nonmonophyletic group, whatever) is only a taxon once it has been given a name.  So, referring to things that are "potential recipients of scientific names" as taxa doesn't make sense to me.
Dick



On Feb 21, 2013, at 11:06 AM, Philip Cantino wrote:

Dear CPN members,

Another left over from last year's discussions is use of the term "taxon" in the PhyloCode.  In a Sept. 29 message, David M. suggested that "taxon" be defined differently than it currently is.  He also suggested that many of the uses of "taxon" and "taxa" in the code could be omitted or replaced with "clade" and "clades".  Kevin and I agree with David's suggestion in general but not in every particular.

I have attached two files to this message.  The one that I encourage you to read first is "Taxon and Art. 1.1.docx", which provides the current wordings of Art. 1.1 and the glossary definition of "taxon", and and our proposed new wordings.  The new wordings will bring the article and the glossary entry into full agreement, which is not currently the case.  The new wording also makes it clearer that the term "taxon" has a general meaning in systematics that extends beyond this code.

The file called "Taxon"-related changes.doc includes the entire code (vers. 4c) with scattered minor wording changes, most of which relate to the word "taxon".  You will need to turn on the Track Changes function of Word to see the changes in this document.

Please look these two documents over soon and send your comments to the listserv.   Let's tentatively set Feb. 26 (next Tuesday) as a target date to call a vote unless substantial discussion develops before then.  If anyone would like more time, please let me know.


Phil


<Taxon and Art. 1.1.docx><"Taxon"-related changes.doc>_______________________________________________
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Richard Olmstead
Professor of Biology and Herbarium Curator, Burke Museum
Department of Biology
Box 355325
University of Washington
Seattle, WA 98195

office: 423 Hitchcock Hall
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