[Tcs-lc] Concepts of Higher Taxa

[Paul Kirk]

This all sounds like a variation of rank inflation which occurs when phylogenetic classifications are mapped to (shoehorned on to) traditional Linnean hierarchies ... so probably best kept as simple as possible in the first instance (or completely avoided).
 
Paul

________________________________

From: Roger Hyam [mailto:roger at hyam.net]
Sent: Tue 29/03/2005 12:05
To: tcs-lc at ecoinformatics.org
Subject: [Tcs-lc] Concepts of Higher Taxa




I have just noticed a big gap in my understanding of the concept of 
taxon concepts and I was wondering what other peoples take on it was. 

My understanding of the circumscription of a genus is biased towards the 
species that are included within it and less so on its description and I 
think this is pretty common. As we go up the hierarchy taxa are defined 
more by their members than by anything else. An author's definition of a 
family is usually more or less just a list of genera arranged into 
intermediate taxa of some kind. 

How is this handled in the Taxon Concept world? If we allow a GUID to be 
created for a definition of genus G1 according to A1 and then some one 
comes along and creates new species level taxon S1 according to A2 and 
says that it has a 'contained in' relationship with G1 according to A1 
does that alter G1 according to A1 concept? 

If so should we automatically create a G1 according to A2 concept and 
circumscribe it as being the same as G1 according to A1 (a contains 
relationship) but with the addition of S1? 

If we do this then the same logic surely applies all the way up the 
chain to the kingdom level or does it stop at one level up? The same 
arguments perhaps apply below species level with people adjusting 
subspecies definitions. 

If we do allow changes in lower taxa to effect upper taxa then we are 
into concept proliferation territory. If we don't then we are not 
reflecting the way people really define taxa. Perhaps we should be just 
thinking of taxa becoming more 'nominal' the higher up the chain we go 
if not we get a new Plantae for every micro species of Rubus that is 
created. 

In short: How do changes to contained taxon concepts affect the concepts 
that hold them? 

Should we perhaps be talking more in terms of classifications (i.e. 
trees of concepts) rather than billiard ball like concepts? An according 
to actually freezes a tree of objects not a single object. 

-- 

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