[Taxacom] Bolboceratinae or Bolboceratidae

[John Grehan]

-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu
[mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Doug Yanega
Sent: Monday, October 23, 2006 5:22 PM
To: TAXACOM at MAILMAN.NHM.KU.EDU
Subject: Re: [Taxacom] Bolboceratinae or Bolboceratidae

I am far - quite far, in fact - from an uncritical supporter of
molecular systematics. Not all molecular data sets are created equal,
however. The genes and gene regions selected, the competence of the
sequencing and alignment, the thoroughness of taxon sampling...all are
factors that can lead to a molecular dataset being either pure gold, or
absolute rubbish. In the present case, the molecular work is excellent
in all respects, while the morphological dataset is, ironically, highly
suspect, including numbers of characters whose homology hypotheses
(i.e., character coding) are virtually impossible to understand, let
alone replicate (esp. the wing articulation and genitalic character sets
- I cannot believe that any two scientists could independently arrive at
the same codings that Browne & Scholtz did).

In the situation described I can well understand the attraction of
molecular data, although the problems of the resemblances representing
overall similarity remain. If homology issues are to be considered
suspect for this group the same would seem to apply to the molecular
data where the homologies are not observable in nature (since they are
constructed through alignment). Perhaps in the future someone will
manage to sort out defensible morphological features. Then it might be a
very interesting comparison.

>  > Morphology alone is not sufficient in this case,
>
>Is this a transcendental truth (i.e. morphology will always be
>ambiguous) or contingent upon current knowledge?

I said "in this case" for a reason. The reason is that, despite a trend
of an opposite nature, sometimes morphological data sets contain more
noise than signal, while some molecular datasets give excellent and
well-supported resolution rather than masses of polytomies. In this
case, the molecular work has the upper hand (and yes, this is only my
opinion). 

No worries on any difference of opinion. 

>It sometimes seems that the more attention given to any group the more 
>contentious and controversial it becomes.

I suspect it depends mostly upon the kind of people who are paying
attention to a group. Of course, one might argue that the more people
working on a group, the more likely it is that at least one of them will
fall short in some respect, thus engendering "controversy".


Or that ambiguity is the reality for many groups.

John Grehan