[Taxacom] Molecules vs Morphology‏

[Jason Mate]

My saturday night´s two eurocents:

> I was not referring to different molecular data sets. Molecular data
> might support an accepted relationship between some taxa, but not for
> other taxa in the group being analyzed. The molecular data is supposed
> to be infallible for the accepted grouping and yet returns a false
> relationship for other taxa. This has occurred in some primate studies.

Accepted
how? Supported by what? False... but if there is no truth there can´t
be falsehood either other than incongruence? I have repated this point
several times, you seem to have accepted one of its versions and then
you turn 180. In the same vein that "molecular" data is not infallible
neither is "morphological". I work with Aphodiinae and most of the
taxonomic developments in the last 20 years have been based on the
morphological equivalent of squeezing-blood-out-of-stones, or in this
case the Holy Grail of aedaegal/epipharyngeal characters. Of course
when you infer the phylogeny with "molecular" data you find the usual
picture: some of the old groups, some of the newer ones, but a lot of
other ones are also there. Obviously some of the newer "molecular" ones
are artifacts or simply reflect the particular history of the genes
used but I already feel confident that the congruent ones are pretty
firm and looking at the morphology of some of the others and seeing
them supported is a confidence boost. Am I kow-towing to morphology´s
infallibility? No, I am accepting the fact that several researchers
using different lines of enquiry and data have reached the same
conclusion! That is the hypothetico-deductive model which I have to
insist asking again, are you using it or do you use a different one?

In
addition the distinction of "molecular" and "morphological" is handy
short-hand but woefully inadequate. Is there a distinction that clearly
separates both in phylogenetics, other than one is based on nucleotide
sequences and the other everything else? Or do we include in the
molecular camp proteins or cellular membrane structures? Please make
your opinion clear because this conversation is descending into
Platonic shadows.

> Wrong translation. Correct translation - congruence helps identify the
> grain from the chaff by identifying grain as that which is congruent
> with molecules, and chaff which is not.

Again
you let your own emotions marr your view. No data source is infallible
in any group or at all levels. If they are guilty of being
gene-groupies you are a morpho-groupie. When the first molecular
phylogenies came out some where so different that one had to wonder
what they were sequencing. It is logical that you expect a degree of
congruence or otherwise you cannot append your new data. But why is the
phenotype the absolute gold standard to which everything should measure
to exactly? Please explain in more than one sentence.


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