[Taxacom] "Tenuinucelli" clade in eudicots?

[Kenneth Kinman]

Hi Richard,
        The question is whether you can get tenuinucellate ovules
through different pathways.  The following statement appears to come
from Albach, Soltis, and Soltis, 2001 paper "Patterns of Embryological
and Biochemical Evolution in the Asteridae" (in the journal Systematic
Botany):          
       "A different ontogenetic pathway may, however, be responsible for
tenuinucellate ovules in the Cornales and some rosid families (see
Philipson 1974)."    Perhaps this is the reason Peter Stevens (in the
APG website) lists tenuinucellate ovules as a synapomorphy for just the
Ericales-euasterid clade.
      But the big question in my mind is whether these different
ontogenetic pathways have been confirmed. I wouldn't be too surprised if
the tenuinucellate ovules in rosids (those families which have them)
arose by a different pathway.  However, I would be surprised if the
pathway in Cornales was different from Ericales (sensu lato) and the
euasterids.  Anyway, notice that they state that these separate pathways
MAY exist, but I could find nothing in the literature showing that such
separate pathways DO exist among the eudicots.      
           ----------Ken Kinman          
 
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Richard wrote:
      Okay, Ken. This may be difficult to accept, but the fact that both
groups have tenuinucellate ovules is evidence that both share a deep
ancestor, whether they are sister groups or not. The fact is evidence
that provides a theory, which can be compared with other theories,
falsified maybe, supported maybe, etc. 
 
I have nothing against the methods of phylogenetics since sister group
analysis is informative about similarity, which allows evolutionary
explanations, e.g. closeness of evolution OR convergence, all of which
are testable. It is the main principle of phylogenetics I disagree with,
namely identification of a supposedly fundamental pattern in nature and
mapping all other facts to that pattern, and all facts that are not
congruent are discarded (epistemological extinction such as synonymy) or
explained away, usually as "convergence."  [[This is a macro, thanks
Curtis!]]