[Taxacom] Paraphyletic tagging

Kenneth Kinman kinman at hotmail.com
Thu Oct 2 19:05:37 CDT 2014




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. 

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> 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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