[Taxacom] DNA only descriptions

[Sergio Vargas]

Hi,

>In human-great ape systematics, for example, combining molecular
>and morphological evidence does not 'explain' anything. It just obscures
>the fact that there is a wealth of uniquely shared morphological
>similarity that does not agree with patterns of molecular similarity.

If molecular and morphological phylogenies point to a different tree,
won't you still need to address the question why the two character
sets point to a different tree?

> Demanding that people do both morphology and molecular comparisons
> obviates the possibility that there are credible reasons for why one my
> reject one or other line of evidence. I would consider it an unjustified
> totalitarian and unscientific restriction.

I am demanding that people at least take the time to provide "credible
reasons" not to use one or other line of evidence and stop using the
"morphological characters are homoplasious" escape to simply discard
data a priori. If you have "credible reasons" to discard data the only
way you could have found these reasons is by the critical assessment
of all available information and the a posteriori selection of
characters for the analysis. Isn't this using both character types?

> Using two sets of (more or less) independent data is good if the results agree (it increases confidence), but
> does not help if the results disagree. It is unclear how best to handle conflicting sets of data, except by finding a plausible
> explanation why one set or other might be wrong ...

I would add: or what biological process could have led to the
discrepancies found, for instance hybridization, incomplete lineage
sorting, etc.

sergio

-- 
Sergio Vargas R., M.Sc.
Molecular Geo- and Palaeobiology Lab.
Dept. of Geo- & Environmental Sciences, Palaeontology and Geobiology
LMU München
Richard-Wagner Str. 10
80333 Munich, Germany
tel. +49 89 2180 17929
s.vargas at lrz.uni-muenchen.de
sergio.vargasr at ecci.ucr.ac.cr