Australopithecus and orangutans

[Curtis Clark]

At 08:52 2003-05-15 -0400, John Grehan wrote:
>My understanding and practice in morphology is to designate apomorphic
>characters.

Two decades ago, systematists were addressing this question. A widely-held
view at the time was that, since apomorphy and plesiomorphy have meaning
only in the context of phylogeny, outgroup comparison was the only
appropriate way of determining them. It was also advanced by many that
outgroup comparison was implicit in parsimony reconstruction. My own paper
(Clark, Curtis and Daniel J. Curran. 1986. Outgroup analysis, homoplasy,
and global parsimony: A response to Maddison, Donoghue, and Maddison. Syst.
Zool. 35:150-154.) is certainly not the  best of the bunch, but I have the
reference at hand and its bibliography refers to others.

The current practice in molecular parsimony analyses is substantially the
same (I don't understand the basics of maximum likelihood well enough to
know if it is true there also). I'm not as familiar with the literature as
I was in my younger days, so if there have been any advances in polarizing
morphological characters, I'm not aware of them. But a priori polarization
based on non-phylogenetic criteria was IMO effectively discredited a long
time ago.


--
Curtis Clark                  http://www.csupomona.edu/~jcclark/
Biological Sciences Department            Voice: +1 909 869 4062
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