My point was that there are serious difficulties in phylogenetic
reconstruction research. Phylogenies derived from different
approaches don't always match -- that's the point.
FYI, I'm not an anti-evolutionist but neither am I a evolutionist. A
rejoice in every little bit of *truth*, so I always ask the question,
is it?
The problem can be better appreciated once one realizes that we don't
know the evolutionary histories, period. In the following paper the
authors *measured* the histories and found significant discrepancies
between the measured and the *predicted* ones. BTW, your are much
better qualify to opine on this since I'm a bioengineer, not a
biologist.
Thanks for your comments
EGM said:
>I said:
>Things are getting weirder. The morphological derived taxa is not
>fitting well with the molecular derived taxa.
>
>Dr. Harper asked:
>This is interesting. Do you have a reference?
>
>I say "ask and you shall receive:"
>"The Coming of Age of Molecular Systematics," by Laura E. Maley and
>Charles R.
>Marshall, Science 23 January 1998.
Not really a very inspiring article IMO! The implication of your first
statement is that phylogenies based on morophology are often not
concordent
with gene-based phylogenies. Certainly there are classic examples of
conflicting gene- and morphogically-based trees but I would say that
this
is the exception and not the rule. Even the authors of the article point
out that "these new molecular data SOMETIMES are very different.." The
article goes on to briefly touch upon many of the causes that can
result in
less than perfect phylogenetic estimations. Certainly one would EXPECT
there to be difficulties in estimating the phylogentic relationships
among
groups of organisms that radiated over a very short amount of time. I
don't understand how things are getting "wierder." Rather than weirder
we
are finding out how particular phenomena can exagerate the results of
our
analysis and how we can increase the confidence in our estimations in
the
future. Also a direct comparison of studies is not always possible and
so
apparent conflicts are usually not as serious as they might seem. Even
in
this paper they give the example of poor taxon sampling and how it can
effect basic topologies of trees. Anyone who has worked with sequence
data
sets knows that underepresentation of groups leaves you vulnerable to
long
branch attractions etc.. which will produce articial groupings.
regards,
joel duff
==
EGM
"in ipso enim vivimus et movemur et sumus sicut"
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