paraphyly

Thomas G. Lammers lammers at FMPPR.FMNH.ORG
Thu Jun 12 14:46:36 CDT 1997


At 10:52 AM 06-12-97 -0700, Barbara Ertter wrote:

>It's not a question of the existence of paraphyly, but rather whether it is
>a mortal sin as far as nomenclature is concerned.  Why is it anathema to
>have taxon A arising from the middle of taxon B?  Isn't it likely that this
>is exactly how evolution works?

Exactly!  "Budding off" of peripheral isolates is extremely common mode of
allopatric speciation.  When it happens, a formerly monophyletic species
becomes paraphyletic.

For an EXCELLENT discussion re: plants, see: Loren Riseberg & Luc Brouillet,
"Are many plant species paraphyletic?", Taxon 43: 21-32. 1994.  I think
Loren subsequently documented paraphyletic origin of a Helianthus sp.  via
molecular methods, but I can't find the ref right now.

Art Cronquist ("A botanical critique of cladism", Botanical Review 53: 1-52.
1987) also devoted much discussion to this problem.


Thomas G. Lammers

Classification, Nomenclature, Phylogeny and Biogeography
of the Campanulaceae, s. lat.

Department of Botany
Field Museum of Natural History
Roosevelt Road at Lake Shore Drive
Chicago, Illinois 60605-2496 USA

e-mail:     lammers at fmppr.fmnh.org
voice mail: 312-922-9410 ext. 317

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"He uses statistics as a drunken man uses lampposts
 -- for support rather than illumination."
                                            -- Andrew Lang




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