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Re: giant birds



That's basically it - though another spin is that an evolutionary
scenario can be mapped onto a tree as a "character" (or, more
appropriately, a suite of characters) after a tree has been constructed,
regardless of the kind of data used to build it (or even the method -
maximum likelihood is the growing method of choice for molecular data
these days).  

chris


Kendall Clements wrote:
> 
> Chris Brochu wrote:
> 
> > It (BCF) can be forced into compatibility with standard phylogenies -
> > in fact, any scenario can be.  I could envision scenarios in which
> > every single character in the matrix is independently derived on
> > every single branch on the tree.  The question is, is that the
> > simplest scenario supported by a given tree?
> 
> I'm not quite sure I follow you Chris, but I suspect like me you think
> we need some objective criterion (i.e. parsimony) to test between
> hypotheses. Tree construction under parsimony is based on minimising
> character reversals. If homoplasy (independent character derivation in
> Chris's words) was this rampant in evolution, we'd never get congruence
> between trees (of extant organisms) based on morphological and
> (independent) molecular characters. We either treat the tree as a
> hypothesis of character evolution or we don't. So on that basis, BCF is
> very unlikely to be supported by a given tree.
> 
> Kendall
> 
> ----------------------
> Kendall Clements
> k.clements@auckland.ac.nz

-- 
----------------------
Christopher A. Brochu
Department of Geology
Field Museum of Natural History
Roosevelt Road at Lake Shore Drive
Chicago, IL 60605

voice: 312-665-7633  (NEW)
fax: 312-665-7641 (NEW)
electronic:  cbrochu@fmppr.fmnh.org