paraphyly, characters, and biogeography

John Grehan jrg13 at PSU.EDU
Thu Sep 16 23:42:06 CDT 1999

I have no familiarity with the classification conundrums regarding the
higher taxa that are a matter of contention on this list, but
Ken Kinman's  reference to stable and useful as favorable criteria seems
to me somewhat artificial and arbitrary. Something may be stable, and even
seen to be useful, but whether there is any necessary relationship between
these criteria and the reality to which they refer is another matter. I
that the flat earth theory was once a stable view, and probably seen as
a useful interpretation of the world.

Regarding paraphyly vs monophyly etc it seems to me sometimes that
its more a matter of how the characters are juggled, and what kind of
computer programs resort the data (which is of itself often contains a lot of
conflict) into something resembling "resolution". The cladograms or any
other tree concepts seem to me to be really just arrangements of
characters, i.e. they
are models of character phylogenies that are interpreted according
to some belief in a historical relationship between these character
arrangements and some kind of genealogical sequence. I'm more of
a biogeographer than systematist, so perhaps the above reveals more
of my ignorance than understanding.

I have used paraphyletic groups in biogeographic accounts where the
basal lineages of a larger group can show a sequence of biogeographic
differentiation even though the more derived taxa are not includeed. Thus
the primitive Leiopelmid frogs may comprise a paraphyletic assemblage,
but they still can show a real biogeographic pattern. The
same goes for the primitive paraphyletic lineages in the ghost moth
(Hepialidae) family that show a classic
Australia-Southern Africa-Eurasia/North America track.

John Grehan

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