revolution

[Robin Panza]

James Lyons-Weiler stated:
>The complexities in modern taxonomic science (in which I am throwing all
>of systematic biology) result primarily from discordance between
>independent sources of evidence for natural phylogenetic relationships.
>Congruence has held a special place in taxonomic science; when new sources
>of data are developed, congruence is almost universally taken as an
>indicator of corroboration.  However, discordance has no ubiquitously
>accepted significance.  Taking trees from new evidence as indicating that
>old tree are wrong is dangerous, because then the conclusions drawn simply
>depend on which data are generated first.  Therefore, congruence does not
>provide a critical test by which to gauge the accuracy of phylogenies..

Phylogenies published today seem to be primarily the shortest tree (or the
concensus tree) generated by PAUP.  A different dataset with the same
organisms may produce a different shortest tree, but how far off is this from
the previously-published one?  Is it nearly as short, or grossly complicated?
I wish someone would start examining this question for organisms for which
multiple datasets have been worked on.  If they are discordant, *how*
discordant are they?  I should think this would provide some evidence about
the validity of both trees (i.e., if they're slightly discordant, perhaps both
are nearly correct; if they're wildly discordant, there's something else going
on that needs to be understood).

Robin Panza                     panzar at clpgh.org
Section of Birds, Carnegie Museum of Natural History
Pittsburgh  PA  USA  15213