[Taxacom] Semantic Web: What is a species?

Richard Zander Richard.Zander at mobot.org
Fri Jan 30 10:20:45 CST 2009

I agree with Ken that species can be thought of as paraphyletic. The
notion of reciprocal monophyly is particularly important with gradual
speciation of two taxa from an ancestral taxon, where one of the taxa is
at least molecularly paraphyletic to the other (different populations
molecularly different) but becoming monophyletic as populations go
extinct, purifying selection occurs, lots of backcrossing between
populations of one species, and general homogenization happens. 

This is the Standard Theory I think among cladists, and few are
concerned with the idea that up to half the exemplars in a study may be
surviving ancestors of the other half.

Richard H. Zander 
Voice: 314-577-0276
Missouri Botanical Garden
PO Box 299
St. Louis, MO 63166-0299 USA
richard.zander at mobot.org
Web sites: http://www.mobot.org/plantscience/resbot/
and http://www.mobot.org/plantscience/bfna/bfnamenu.htm

-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu
[mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Kenneth Kinman
Sent: Friday, January 30, 2009 9:23 AM
To: taxacom at mailman.nhm.ku.edu
Subject: [Taxacom] Semantic Web: What is a species?

Hi Ilya,
      The distinction between tokogenetic and phylogenetic is useful to
a point.  However in reality, I believe there is a continuum of
possibilities between strictly tokogenetic and strictly phylogenetic.

      When a species is well on its way to dividing into two species,
its overall population structure has shifted considerably toward the
phylogenetic side of the continuum (but it is still just one species).
Therefore, I think it is perfectly reasonable to think of paraphyletic
mother species giving rise to daughter species.   
      I think it is great that Hennig got us on the road to rigorous
cladistic "analysis". However, when it comes to translating the results
into strictly cladistic classifications and nomenclature, it created a
divisive and confusing mess that only continues to get worse.  And its
most extreme manifestation (PhyloCode) hasn't even gone into effect yet.
           ---------Ken Kinman                       

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