[Taxacom] DNA only descriptions

[Kenneth Kinman]

Hi Kim,
       Well, yes and no.  Yes, I agree that we should use all possible
sources and weigh them appropriately on a case by case basis.  However,
whether molecular data provides better resolution than morphological
data must also be evaluated on a case by case basis.   
      At this point, it is largely a matter of how much molecular data
is available for a given taxon.  And even then, it will still vary from
taxon to taxon.  Not surprisingly, some taxacomers gravitate to giving
either morphological data or molecular data the edge (more weight), but
this may be due to the particular taxa in which they have the most
experience and expertise.     
       In the end, the evaluation on a case by case basis must take into
account how much molecular data is available, and the difficult task of
weighing that against what morphological data is available.  So I
definitely agree with you that "any absolutism won't work".  My view is
some workers overly emphasize morphology (e.g., John Grehan on great ape
phylogeny), and perhaps even more researchers now overly emphasize
molecular data just because it is presently a popular bandwagon.  For
many taxa, an appropriate weighing "from all possible sources" is still
a work in progress, and molecular data is perhaps still often given too
much weight when such data is still far from complete.  What you regard
as "far more [molecular] data" may not impress morphologists of some
taxa.  As you said, it has to be weighed on a case to case basis, and
therefore it is unwise to make any generalizations one way or another
without reference to the particular taxa being discussed.  Many
disagreements on Taxacom are due to different philosophies, but others
are due to varying experiences with their particular taxa of interest.
How to appropriately weigh the available data is obviously still a a big
problem for many taxa.      
           ----------Cheers,
                                Ken Kinman
----------------------------------------------------------
Kim van der Linde wrote:
     I hope you guys understood that I was to a degree playing advocate
of the devil. What we need is discussion about ho0w to integrate the
various ways of unraveling species boundaries, evolutionary
relationships etc. 
    Yes, a single COI sequence won't be enough in some/many cases.
Obviously. But it is a start. Gut bacteria, endosymbionts, and what ever
more can mess up the signature. 
Crytic species, yes, I agree, ideally we would like to have the
reciprocal crossing schemes showing incompatibility. I would like to see
those also for morphologically closely related species, because the same
issues arise there. 
I think any absolutism won't work. But my experience is that molecular
phylogenies often have a substantially higher degree of resolution than
cladistic phylogenies. And that is logical, because often, it is based
on a lot more data than cladistic studies. So, I think we should use all
possible sources and weigh them appropriately on a case by case basis. 
Anyway, that is where I stand in this discussion.