[Taxacom] This week's paraphyly discussions

[John Grehan]

I guess one might regard 'natural' and any grouping that is accepted by
an individual. I have a preference to natural and taxon representing a
monophyletic group with all descendant members included. Paraphyletic
groups seem to me to be an arbitrary assemblage of organisms according
to an individual preference - useful or stable or not.

One could make up the 'taxon' "all farm animals in England" or "all farm
animals in South Africa". Are such groups 'natural' in any meaningful
sense of classification in evolutionary biology?

John Grehan

-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu
[mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of
dipteryx at freeler.nl
Sent: Monday, December 20, 2010 9:29 AM
To: taxacom at mailman.nhm.ku.edu
Subject: Re: [Taxacom] This week's paraphyly discussions

Van: taxacom-bounces at mailman.nhm.ku.edu namens John Grehan
Verzonden: ma 20-12-2010 14:39

> If a taxon is paraphyletic then it is not a taxon.

***
This is circular reasoning. By definition, a taxon is a 
taxonomic group (or taxonomic unit), that is, a group 
that a taxonomist thinks is worth distinguishing, as 
belonging together (in some way).

If somebody calls this group paraphyletic, this will 
usually be because he does not accept paraphyletic groups,
so in that case, such a group is a (usually 'natural') taxon
to the taxonomist who accepts it, but it is paraphyletic 
(and 'artificial') to the person who does not accept it.

Paul van Rijckevorsel
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