The attitrion of taxonomic expertise
Doug Yanega
dyanega at DENR1.IGIS.UIUC.EDU
Fri Oct 18 12:31:49 CDT 1996
Alan Harvey wrote:
>
> James Lyons-Weiler wrote:
>
> >My point is that if statistical techniques such as maximum likelihood were
> >not developed, the criterion of discordance would apply to both
> >morphological and molecular data. Because the tecniques apply to
> >molecules, the fault of discordance went to the untested partition of the
> >data, namely, morphology.
> >
>
> Maybe it's just me, but favoring partition A over partition B simply
> because you applied a statistical test to A but not B seems to violate the
> most basic premises of statistical testing. In any case, _my_ point was
> that statistical methods came into being because more direct ways of
> analyzing the results of molecular data sets were unavailable.
> Morphologists seldom use these statistical methods because they prefer the
> direct approach, and because of concerns about the statistics themselves,
> which, for example, seem to address questions that, in practice, are seldom
> relevant to morphological data sets (e.g., "Is there a significant
> phylogenetic signal in this data set?").
Actually, I'm quite sure it goes beyond that, as James suggested - it
is not that morphologists *choose* not to use statistical tests, but
that many of the statistical tests used to evaluate molecular data can
NOT be used on morphological data; what is the *probability* that a
bristle on a fly head will appear? Disappear? Become thicker, or longer,
or flattened, or plumose, etc.?? Molecular statistical analyses
frequently invoke character transition probabilities, for which there are
available estimates. And yes, I have seen folks who claim this makes for
inherent superiority. I notice, too, that despite claims otherwise at the
outset, this *has* become a bit of a molecules vs. morphology debate -
though this is perhaps only natural, given that the reduction in the
proportion of morphologists in the systematic community does indeed seem
to be directly related to the growing molecular ranks. Whether or not any
of us put stock in the philosophical aspects of the debate, it does seem
to be translating into a genuine battle as far as employment and funding,
and I for one find it disheartening to see traditional systematics
getting the short end of the stick so consistently, when everyone DOES
realize how truly important it is.
Sincerely,
Doug Yanega
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