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Learning cladistics (was Re: Dinosaur Web Pages' Re-Opening)



In a message dated 97-09-04 15:54:28 EDT, znc14@ttacs1.ttu.edu writes:

<<  >         In the absence of a phylogenetic hypothesis to the contrary, we
are
 > left with this conclusion. Care to clade a better one?>>
 >Since I don't accept cladistic analysis as anything more than simply one
more
 >way of constructing phylogenies, I don't see what good this would do.
         Since you have no means of demonstrating your argument without
 constructing a testable phylogeny of your own, I suggest you either learn
 cladistics, or develop an alternative which is just as testable, just as
 relatively objective, and just as reproducable. Then develop an alternative
 hypothesis. Then make statements like your original one above. Then we can
 all compare the two, and accept or reject to our heart's content. >>

Cladistics is trivial. What's not as trivial is recognizing characters and
character suites worth subjecting to analysis. And: cladistics is >not< as
testable as you think. I have repeatedly called for a test of the methodology
by doing a double-blind cladistic analysis of a known phylogeny (one
constructed, for example, by a computer). We need to get a handle on when
cladistics gives us a confirmed, correct phylogeny and under what
circumstances cladistics >fails to do so<. For example, I assert that if
there are a significant number of convergences and homoplasies in a
phylogeny, then cladistics will not perform correctly. And we won't know it's
performing incorrectly, because cladists will not accept a non-cladistic
check on their cladograms. It takes a >lot< of faith to believe that analysis
of an ever-larger suite of characters will in all cases eventually converge
on the correct phylogeny instead of winding into an ever-deeper morass of
error.