[Taxacom] DNA only descriptions

[Sergio Vargas]

Hi there,

> 2) 'traditional taxonomists are happy to have molecules'... 'Happy to
> *have*' seems to imply that some molecular systematist will be kindly
> generating those data for a 'traditional' systematist to *have*.  Good
> enough, but I have not heard criticism directed toward morphologists (or
> biochemists or paleontologists...) failing to include molecular (or
> ecophysiological or biogeographical, etc) data in their studies.

yes, that's also an issue and that's why I think all available
information on the organism should be included when possible. However,
there seems to be more problematic (in some cases) for morphologists
to include molecular, biogeographical or biochemical data when working
on the revision of a group with no recently collected material and
museum only samples. For many groups, many nomenclatural problems come
from old species descriptions where you have nothing but the holotype
if you are lucky.

> This is really not true across the board. Just like some
> people are strictly in morphology only, some people focus on molecules. Some
> people quite successfully combine the two. I see no greater problem with
> molecular folks focusing on one kind of data than morphological folks
> focusing on one kind of data. Eventually it must all get included in some
> 'big picture' idea of evolution, yes?

yes and no... I see big problem with either morphogical folks
focussing on morphology and molecular folks focussing on molecules, in
my experience if do this you MAY end up simply communicating that a
the taxonomy of a group is a big mess or that this genus is
para/polyphyletic without any nomenclatural consequence of this
results. The discrepancies between molecular and morphological
phylogenies deserve to be explained and you cannot do this unless you
do both... even if it is hard.

> 4) 'cladistic' does not refer to morphological data while 'phylogenetic'
> refers to molecular data. In the modern sense, they are essentially the same
> approach and can (and should) be applied to both (and other) kinds of data
> wherever the assumptions are met or can be properly dealt with.

d'accord!


> A properly conducted molecular taxonomic study is every bit as demanding as
> a properly conducted morphological study. There appears to be an
> undercurrent of 'molecular is easier' and this is really quite mistaken IF
> you do it well.

d'accord, if you do it well you may will end up digging deep into the
nomenclature of the group you are studying... not necessarily of
course, you can do molecular only with very good results; whatever
good means...

>By criticizing every molecular-only study, you are demanding
> that every molecular researcher essentially carry out two high-quality
> studies.

perhaps, I am a demanding person...

> Are you prepared to demand the same from every morphologist?

I am, and most highly cited journals are too. Curiously, you can
publish a molecular only study without any further discussion on the
discrepancy with morphological expectations (but the classical
taxonomy is a mess) in many highly cited journals but you cannot do
the same using morphology only. You would need "independent sources of
evidence" to assess the validity of the phylogeny. I now work with
molecules but try to include morphology and nomenclatural issues in my
work when ever possible.


> I would prefer folks do whatever they find most intriguing as well as they
> possibly can, and I would be delighted if some handy morphologist wanted to
> collaborate in my group (hint, hint).

here you come to an important point. I think there should be more
communication between morphologists and molecular systematists, and
less interest in proving oneself right at all cost


cheers

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