cladobabble

[Kendall Clements <k.clements@auckland.ac.nz>]

The "debates" on phylogenetics on this list brought to mind Sisyphus, 
the legendary king of Corinth. Sisyphus was condemned by the gods to 
forever roll a boulder to the top of a hill, from which it always 
rolled back to the bottom. Tom Holtz, Chris Brochu and others deserve 
sainthood for the continual patience they show. My attitude is simply 
to plug for objectivity and repeatability.

That said, there are independent ways of "testing" phylogenies. For 
example, the recent tripartite bilaterian animal phylogeny based on 
mitochondrial sequences conflicts in several very important respects to 
the "traditional" tree, which was based on a speculative assessment of 
the order in which body plans may have evolved. I've just taught the 
new tripartite tree to first year students. Anticipating the comment 
"Why should we believe this tree over the other" from students who were 
not totally au fait with phylogenetic methodology, I described the 
pattern of hox clusters amongst bilaterians. Each of the three great 
clades of bilaterians has a distinct hox cluster, a result 
which independently supports the new molecular tree. 

Dinosaurs are extinct, so perhaps there is not much hope of a similar 
independent source of information. But perhaps developmental studies of 
birds may offer some hope (I've got to say I'm in no doubt here - but 
it might silence the doubters). I raised the issue of paedomorphosis 
earlier, to deafening silence!

Kendall

----------------------
Kendall Clements
k.clements@auckland.ac.nz