[Taxacom] Paraphyletic tagging

Stephen Thorpe stephen_thorpe at yahoo.co.nz
Thu Oct 2 19:17:34 CDT 2014


Thanks Ken - at least someone understood my words! I'm not sure if we need "double tagging", since a single tag serves to alert the reader to the paraphyly, but explanations are perhaps placed elsewhere, so as not to overcomplicate the classification itself. The primary function of classification is still information management, so to complicate it with other issues detracts from that function, which is why I would never opt for a phylogenetic classification instead of a Linnean one.
Cheers,
Stephen

--------------------------------------------
On Fri, 3/10/14, Kenneth Kinman <kinman at hotmail.com> wrote:

 Subject: Paraphyletic tagging
 To: "Stephen Thorpe" <stephen_thorpe at yahoo.co.nz>, "John Grehan" <calabar.john at gmail.com>
 Cc: "Curtis Clark" <lists at curtisclark.org>, "taxacom at mailman.nhm.ku.edu" <taxacom at mailman.nhm.ku.edu>, "AlanWeakley" <weakley at bio.unc.edu>
 Received: Friday, 3 October, 2014, 12:05 PM
 
 
 
 
 
 
 
 Hi Stephen,
        I agree that
 abandoning Linnean ranks is disadvantageous (for a variety
 of reasons).  Thus tagging is the answer.
  Actually one might say that my classifications employ
 a "double tagging" system, because I not only tag
 the name of the paraphyletic mother taxon itself (such as
 Class Reptilia%%), but also include markers (tags) showing
 what daughter taxon (or taxa) was paraphyletically removed
 from it---in the case of Reptilia there are two such
 markers: {{Aves}} and {{Mammalia}}, which can be placed next
 to their sister taxa within Class Reptilia.  In an
 informational sense, such markers render the paraphyletic
 mother group holophyletic, because they explicitly show what
 descendant taxon has been removed and what subgroup it is
 related to.  It's like having your cake and eating
 it too (paraphyly and holophyly at the same time).  
    
 -----------------------------Ken
 P.S.  Thus we can say that birds are
 dinosaur descendants (not "birds are dinosaurs").
  And we can continue saying that dinosaurs went extinct
 at the end of the Cretaceous or that the asteroid killed off
 the dinosaurs. 
 
 ----------------------------------------------------------------------------------------------------------------
 > Date: Thu, 2 Oct 2014 13:33:14 -0700
 > From: stephen_thorpe at yahoo.co.nz
 > Subject: Re: [Taxacom] Paraphyletic groups as natural
 units of biological classification
 > To: calabar.john at gmail.com
 > CC: lists at curtisclark.org; taxacom at mailman.nhm.ku.edu;
 weakley at bio.unc.edu; kinman at hotmail.com
 > 
 > John,
 > I think what you are saying is that a paraphyletic
 group is one which has no known synapomorphies (e.g. MM
 minus M), even though it could later be shown to be
 monophyletic (i.e. sister taxon to M) if synapomorphies were
 discovered. My point, however, is such paraphyletic groups
 may be commonplace, and it may never be possible to discover
 synapomorphies. Therefore, if we were to try to force a
 Linnean classification to be strictly monophyletic, we would
 have a problem. One possible solution is to reject Linnean
 classification in favour of a rankless phylogenetic
 classification, but this has the major disadvantage of
 rendering a vast amount of published information obsolete. I
 think it is far more sensible to retain Linnean
 classification, with formally names and ranks for
 paraphyletic groups. All we need to do is tag these names
 somehow as being paraphyletic, such as by putting the name
 in double quotes (e.g. "Reptilia"), but they are
 still formal names, governed by the appropriate code of
 nomenclature (actually not in the case of Reptilia, which is
 unregulated by the ICZN). This way, the results of
 phylogenetic studies is not necessarily to change the
 classification, but just to tag names for paraphyletic taxa.
 A reclassification may still be appropriate in cases with
 very high phylogenetic support. The problems arise when
 people start rejecting formally named taxa just because they
 are paraphyletic according to your definition (i.e. based on
 no known synapomorphies). Not sure how much sense this
 makes, and apologies for any "using words any old way I
 like" ...
 > Stephen
 > --------------------------------------------
 
 
  		 	   		  
 



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