More on human-orangutan analysis

[John Grehan]

>Whether the "proposeed morphological synapomorphies" are REAL
>synapomorphies depends on which tree is right.  Each tree will delimit
>different groupings of potential synapomorphies, and the job of the
>phylogeneticist is to figure out which grouping is to be preferred.

Agreed in that the initial set of characters qualify as potential
synapomorphies in the first place.

>The assignment of character states as apomorphic, synapomorphic,
>pleisiomorphic, etc. depends on the tree; the preferred tree is chosen
>based on the actual character states, not from a priori judgements
>about which character states are synapomorphic.
>Am I beating a dead horse here?

Probably. What I don't agree with is the treatment of molecular characters
as cladistic in that they are not individually identified as potential
synapomorphies. My current understanding is that in morphology it is
possible to evaluate each character individually for homology and a shared
derived status (this is the a priori part). When there are competing
clusters of such characters I agree that in the final analysis the
'confirmed' synapomorphies are those that are best supported (this being
the a posteriori part). For the orangutan issue it looks like the inclusion
of the full suite of orangutan characters normally left out of those
morphological studies supporting the human-chimp relationship results in
better support for an orangutan-human clade over a human-chimp clade.

John Grehan

>_____________________________________________________________
>Will Fischer                       wfischer at uts.cc.utexas.edu
>
>University of Texas at Austin      Lab Ph.: 512-232-7114
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Dr. John Grehan
Director of Science and Collections
Buffalo Museum of Science
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