[Tcs-lc] concepts of Higher taxa

[Martin Pullan]

I think the nature of the disagreement about what I said earlier arises
because there is a fundamental difference of understanding of taxon
concepts. I know this is a long standing debate but it is becoming
apparent that the issues involved have not yet been resolved with repect
to how TCS should be constructed. I know Rich has already had a go at
this but I would like to have a stab at it myself.
 
Basically I have to take issue with the statement "publication of a new
species always changes the circumscription of the genus!"  because the
statement begs the question what is "the genus".  If we are adopting a
concept oriented point of view then there are potentially many concepts
of the genus. To my understanding at the moment it is not necessary to
identify the specific concept of the genus one is using when publishing
a new species. Therefore when there exist mulitple concepts of a genus
it is not possible to determine which genus concept is being expanded by
the publication of the new species. This could be a case for requesting
a change in the codes such that the specific concept being used must be
identified when publishing a new name. However, as it stands at the
moment, the publication of a species within a genus is a purely
nomenclatural exercise required to satisfy the demands of the binomial
naming system and has no influence whatsoever on any existing concepts
of the genus. In order for a new species to be incorporated into a
generic concept a specific act of inclusion must be performed at which
point a new generic concept is created. For simplicities sake it would
be sensible to allow new concepts constructed in this way to inherit
from the specified earlier concept. This would allow for Gregor's ad-hoc
mode of concept expansion although it would lead to an inflation of the
number of concepts in existence - ie a new higher taxon concepts would
have to be created each time a new member was added - but I don't think
this is bad thing as these would not be new "potential concepts" - they
would be new real concepts.
 
The above arguements of course begs the question what constitutes a new
publication of a higher taxon - I don't have an answer to this question
but I think that the strict interpretation of publication as presented
in our Prometheus work would have to be relaxed in order to support
this.
 
As a counter to this it could be argued that all concepts of the higher
taxon are expanded by the publication of the new member but I think that
this would be wrong because I adhere to the concept of ownership and
immutablility. That is a taxon concept as published by an individual
belongs to that person and once published cannot be changed - even by
the owner of the concept. It is a kind of version control mechanism and
one that is essential  if we are to take a concept  oriented approach
(as opposed to a name oriented approach ) to indexing into non-taxonomic
data - eg DNA sequence data, ecological data, phytochemical data etc. If
we allow the the higher taxon concepts to be expanded willy nilly merely
by the publication of new species then it becomes much harder to
identify the version of the higher taxon concept that was being adhered
to when the data was captured making it much harder to reason about the
comparability of different non-taxonomic data sets. 
 
Martin

Dr. Martin Pullan

The Royal Botanic Garden Edinburgh

Web site: http://www.rbge.org.uk

Phone: (+44) 0131 248 2908

Fax: (+44) 0131 248 2901

 

	-----Original Message-----
	From: tcs-lc-bounces at ecoinformatics.org
[mailto:tcs-lc-bounces at ecoinformatics.org] On Behalf Of Paul Kirk
	Sent: 31 March 2005 07:32
	To: tcs-lc at ecoinformatics.org
	Subject: Re: [Tcs-lc] concepts of Higher taxa
	
	
	I disagree; publication of a new species always changes the
circumscription of the genus! Since at least one components which define
the genus when the new species is described (the new species) have
changed
	 
	Consider these hypothetical examples:
	 
	Genus Aus Smith SEC. [everyone up to now] has species with
flowers that are red or yellow; a new species by Jones has blue flowers
thus genus Aus Smith SEC. Jones has a new circumscription.
	 
	Genus Aus Smith SEC. [everyone up to now] has sequence data
represented by GenBank acc. numbers 1234, 1238, 1239 ...; a new species
by Jones have sequence data represented by GenBank acc number 2375 thus
genus Aus Smith SEC. Jones has a new circumscription.
	 
	I am not sure how anyone can say the cicumscription of the genus
has not changed, unless we are using different definitions (concepts) of
the words we use to communicate - often a problem as we all know too
well ;-)
	 
	pAUL
	 
	> 2) I also believe that it is erroneous to consider that the
pubication 
	> of new species constitutes an expansion of of the existing
concepts of 
	> the higher taxon to which they are stated to belong. 

	In my view, it may or may not.  Whether or not the publication
of a new species within a genus expands the genus concept in which it
was placed (relative, e.g., to the concept intended by the original
creation of the genus name) depends on subjective judgement. In most
cases, I suspect that it does not (should not) alter the genus
circumscription.

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