[Taxacom] Molecular data and synapomorphies

John Grehan jgrehan at sciencebuff.org
Tue Dec 2 07:27:59 CST 2008

> -----Original Message-----
> From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-
> bounces at mailman.nhm.ku.edu] On Behalf Of Alan DAvid Forrest

> Finally, while molecular data may be based on a few exemplars, when a
> list of extensive analyses (cytology, biogeography et al) is given it
> should be noted that this list is missing for the vast majority of
> groups studied, and for some (ie cytology) it is very unreliable due
> the lack of voucher specimens deposited and the low level of detail
> published.

I would add emphasis to this in that one of the problems I am finding is
that if the molecular data is available, it is in formats that require
some familiarity with, and access to, software that will make the data
accessible. I have found that even molecular systematists can have
trouble with accessing other data formats. Also, there is the additional
problem of the lack of permanency of access (as mentioned before) or
refusal of authors to provide the data (even when they say in the
published article that requests for the data can be made to the
authors). This is voodoo systematics.

> I would re-iterate that a combined analysis of several data can be
> informative than either a single type of data, or a priori measuring
> data against another. 

Not necessarily. If the several types of data are being analyzed
phonetically, for example, then it's no better for that.

In the group we have been working on
> (Antirrhineae) one can find morphological data to support different
> hypotheses depending on the characters chosen - including characters
> that follow the same patterns as the moleclar data. For
> this means different authors will give different classifications based
> upon personal opinion, preference or even reasoned argument about the
> evolution of the characters themselves. Better, surely, to use
> data sources for comparison for a more informed interpretation?

Not necessarily (depending on what one means by a 'more informed
interpretation'). Ad hoc arguments for or against a particular set of
data are just as possible in molecular as in morphological evidence, and
I have seen molecular systematists come up with quite inventive ways of
dismissing molecular data they do not like.

John Grehan

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