[Taxacom] Phylocode vs Linnean nomenclature, again.

[Stephen Thorpe]

with a comment like that, Robin, you obviously need to "get clade"!! :)

Stephen




________________________________
From: Robin Leech <releech at telus.net>
To: Richard Zander <Richard.Zander at mobot.org>; Curtis Clark 
<lists at curtisclark.org>; taxacom at mailman.nhm.ku.edu
Cc: Peter Kuchar <peterkuchar67 at gmail.com>
Sent: Mon, 18 April, 2011 5:54:49 AM
Subject: Re: [Taxacom] Phylocode vs Linnean nomenclature, again.

To clade, or not to clade, that is the question.
With apologies to Willie Shakespeare.
Robin

----- Original Message ----- 
From: "Richard Zander" <Richard.Zander at mobot.org>
To: "Curtis Clark" <lists at curtisclark.org>; <taxacom at mailman.nhm.ku.edu>
Sent: Sunday, April 17, 2011 10:58 AM
Subject: Re: [Taxacom] Phylocode vs Linnean nomenclature, again.


"Clades will be named." Well, sure, but what are clades? Linear series of 
taxa changing into taxa? No chance. Phylogenetic trees are actually clusters 
of exemplars nested by a hierarchy of shared traits. The tree exists in the 
present. The little lines drawn from cluster to cluster are helpful to keep 
track of nesting, but they are just visual aids. A clade is a cluster of 
exemplars in present time, a result of evolutionary processes in the past. 
Clades are named but the names represent the results of processes, and there 
is no theory involved (beyond the trivial implication that applies to all 
clusters that similarity is caused by evolution; of course it is).

A paraphyletic taxon is a phylogenetic artifact. Saying that "paraphyletic 
taxa cannot coexist with monphyletic taxa that cross grade boundaries" is a 
problem for phylogeneticists, not evolutionary taxonomists. A paraphyletic 
taxon is an apparent, theoretic (note use of the word "theory") ancestral 
taxon surviving unto the present via exemplars that cussedly will not 
cluster well on a cladogram.


* * * * * * * * * * * *
Richard H. Zander
Missouri Botanical Garden, PO Box 299, St. Louis, MO 63166-0299 USA
Web sites: http://www.mobot.org/plantscience/resbot/ and 
http://www.mobot.org/plantscience/bfna/bfnamenu.htm
Modern Evolutionary Systematics Web site: 
http://www.mobot.org/plantscience/resbot/21EvSy.htm


-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu 
[mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Curtis Clark
Sent: Friday, April 15, 2011 8:28 PM
To: taxacom at mailman.nhm.ku.edu
Subject: Re: [Taxacom] Phylocode vs Linnean nomenclature, again.

> FYI, a debate at Yale this very afternoon!(The newspaper article below was 
> brought to my attention by a sharp-eyed Commissioner, but strangely it 
> wasn't advertised on Taxacom or the ICZN listservers ;-)  It might be fun 
> to have a first-hand report, if any Taxacomers happen to be attending.
>
People will use the names that are useful in the work they do, and if those 
names don't exist, they will create them.

Linnaean naming, as practiced in the latter part of the 20th C, had two 
issues that made it difficult for phylogeneticists to use. First, 
paraphyletic taxa cannot coexist with monphyletic taxa that cross grade
boundaries: there will never be a Linnaean taxon name for the clade 
Dinosauria in any system that includes Reptilia (Ken Kinman notwithstanding, 
because his system has never caught on).

Second, ranking has both enomous advantages and enormous disadvantages:
the former by estabishing the topology of a hierarchy without requiring a 
detailed knowledge of its members, and the latter from the difficulty of 
making changes to a hierarchy that change ranks, because in Linnaean 
nomenclature, that almost always means a change of name.

In an alternate universe, biologists and texbook authors would have rapidly 
adopted clade-based taxa, there would have been a spurt of renaming, and the 
Linnaean system would have been intact. But that didn't happen, for two 
reasons. First, phylogenetics didn't catch on as fast as its proponents 
would have liked, and there are a number of people (perhaps all on this 
list) who still reject it. Second, molecular studies helped solve some known 
taxonomic conundrums (e.g., the heterogeneous nature of the Scrophulariaceae 
in the flowering plants) and exposed other unknown issues, all of which led 
to the need for multiple name changes.

Phylocode arose from that. Some Phylocoders I've talked to felt that named 
clades would always be second-class citizens in Linnaean nomenclature, so 
they saw the only solution to be a new code. If there's any "blame" for 
Phylocode, it can be found in the attitudes of taxonomists who want to 
preserve grade-based, heterogeneous taxa.

The use of unranked clade names in Linnaean taxonomies is an alternative 
(and one that I support over Phylocode), but *clades will be named*.

--
--
Curtis Clark
Cal Poly Pomona



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