[Taxacom] Molecules vs Morphology‏

[John Grehan]

> bounces at mailman.nhm.ku.edu] On Behalf Of Jason Mate

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? 

In primate studies there have been studies that emphasize results that support an 'accepted' relationship such as human, pan, then gorilla, but the same data source produces relationships for other groups that are not accepted (for example putting lesser apes closer to humans and African apes than orangutans).

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. 

???? lost me here.

In the same vein that "molecular" data is not infallible
> neither is "morphological". 

Agree absolutely totally 100%!!!!!!!

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?

When here is congruence no one has a problem with the results.

> 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.

This is a good question. Molecular is generally represented by base counting of one sort or another. Beyond base counting the difference between 'molecular' and 'morphology' begins to blur, although one might also argue that so-called genetic evidence is really DNA morphology of one kind or another. Most conversations on TAXACOM (and probably any list) dealing with very different points of view tend to 'descend' into 'Platonic shadows' of one kind or another, and the conversations usually peters out until it is raised again.

> > 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. 

Agree 10%

If they are guilty of being
> gene-groupies you are a morpho-groupie. 

Hmmm...but it stands that they are arguing that molecular are the decider. I am only suggesting it is not necessarily so. It is true that in the case of the orangutan I think the morphological evidence is stronger and that the molecular evidence is plagued by problems of primitive retention - but of course that's just my opinion.

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.

I cannot for the simple reason that I do not view the phenotype this way. If your read the recent publication on the orangutan theory you will see that our principle argument is that the morphological evidence is not necessarily falsified by the molecular incongruence. I can not offer a recipe for anyone to make a decision about that. For me, I find the fossil correlation intriguing to say the least. But for others it may be irrelevant.

John Grehan

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