[Taxacom] Paraphyly/predictivity

Peter Stevens peter.stevens at mobot.org
Sat Mar 28 13:06:11 CDT 2009

well, there are a variety of definitions of predictivity out there.   
But thinking of common nouns and classifications, in folk  
classifications and in language generally, when nouns are members of  
contrast sets, they are generally non-overlapping - that is, one does  
not include the other. It clearly helps in communication.  This might  
be relevant when we are thinking of paraphyly and monophyly.  When I  
was working on my thesis, it was a matter of some interest that  
Ericaceae (the rhododendron/blueberry/heather family) were so poorly  
represented in Australia - except that it has turned out that they  
are very well represented there, but we were calling them  
Epacridaceae then, and so we thought that they were irrelevant when  
thinking about the distribution of Ericaceae...


On Mar 28, 2009, at 2:45 AM, Mike Dallwitz wrote:

> Barry Roth wrote:
>> I'm not sure why I would want to make a classification unless I  
>> thought I
>> could get something more out of it than what I put into it. And I  
>> think this
>> boils down to predictivity. Because of the fact of organic  
>> evolution, the
>> classification that best serves this need / desire will be one  
>> strongly
>> grounded in phylogeny.
> One thing that you get out of any classification that includes  
> names is the
> ability to communicate. All common nouns correspond to  
> classifications,
> which are presumably chosen (or evolve) for their usefulness for
> communication, which probably depends on our ability to mentally  
> picture and
> remember the concept of the noun, which is probably related to its
> predictivity in some sense.
> Have classifications based on cladistic methods been shown to have  
> better
> predictivity than other classifications? Predictivity could (for  
> example) be
> defined as in
> Gower J.C. 1974. Maximal Predictive Classification. Biometrics 30:  
> 643-654.
> Colless D.H. 1984. A method for hierarchical clustering based on
>      predictivity. Systematic Zoology 33: 64-68.
>> This also makes me more look charitably on monophyletic (i.e.,  
>> holophyletic)
>> groups than paraphyletic groups.
> Does this mean that belonging to a paraphyletic group such as reptiles
> usually has less predictive value than belonging to any of the  
> monophyletic
> groups to which reptiles belong?
> -- 
> Mike Dallwitz
> Contact information: http://delta-intkey.com/contact/dallwitz.htm
> DELTA home page: http://delta-intkey.com
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