paraphyly and polyphyly

Kelly Miller megadytes at YAHOO.COM
Thu Nov 11 12:47:31 CST 2004

Steve Farris wrote a paper attempting to formalize the
definitions of paraphyly and polyphyly using a given,
fixed topology and group membership variables rather
than actual character information.  In this way he was
able to construct operational definitions allowing
arbitrary groups in a specified phylogenetic
hypothesis to be distinguished as monophyletic,
polyphyletic and paraphyletic without referencing any
real characters or their evolution.  The solution
converges on something very like Hennig’s or Nelson’s
earlier definitions, but decides operationally whether
an ancestor belongs to a particular group or does not.

Farris, J.S. 1974. Formal definitions of paraphyly and
polyphyly. Systematic Zoology 23: 548-554.

Kelly Miller
Brigham Young University

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