Arthropod Evolution

[Robin Leech]

Jeff and Others,

The money for "traditionalists" to do intensive, original morphological and
taxonomic research is simply not there.  THAT is the reason for nothing
being done in this field.  It is not for lack of interest.  Faculty can
support neither their own research, nor that of students, in this area.  In
fact, each time someone does more original morphology work, it is a real
contribution for everyone, including the moleculars and taxonomists.

What is needed is money, and then cooperation between the moleculars and the
morphologists and, yes, even taxonomists.  Relatively speaking, the
moleculars are on a roller coaster ride financially, and the rest of us are
back at the loading dock, able to do no more than watch the riders.

Governments are frugal and stingy, especially the Government of Canada, and
unless a government sees where it can make political hay for future votes,
the funding is not there.  Here in Canada, for example, the federal gov't
just committed $100 million for SARS research. (Note that the money did not
come in the heat of SARS, but after!)  This is a high-profile area, lots of
publicity and politics.  This from a government that could not find money to
do many other things of lower social and health profiles for the past few
years, and which has been cutting back even on firearms safety courses.  Now
the benevolence of our federal govt can be seen in high profile.

I am waiting to see if similar amounts of money will be calved off for
research on the Nile Virus - again a high profile, political topic, and
which may become a big problem in Ontario and westward.

Perhaps what academics should do is go to large industries (Shell, Esso,
etc.), prick their societal consciences, and try to set up say $50,000 to
$100,000 research funds for non-directed research.

Robin Leech

----- Original Message -----
From: "Jeff Shultz" <js314 at UMAILSRV0.UMD.EDU>
To: <TAXACOM at USOBI.ORG>
Sent: Thursday, May 08, 2003 9:30 AM
Subject: Arthropod Evolution


> Hi,
>
> A few comments about arthropod evolution.
>
> 1. Pancrustacea or Tetraconata (= Crustacea + Hexapoda) is extremely well
> supported by many different kinds of evidence (mostly molecular). The
appearance
> of continuing debate is due largely to certain traditionalists who
continue to state the
> same arguments over and over, but now in capital letters and exclamation
points
> along with a blanket rejections of results from molecular data.  A real
debate would
> entail two or more camps who are continually marshalling new evidence.
This isn't
> happening. Frankly, I would like to see more original morphological
research in this
> area, but the traditionalists don't seem interested in doing original
morphology, just
> rehashing the literature.
>
> 2. Manton must be congratulated for stimulating so much research. She
erected a
> huge edifice that had to be knocked down brick by brick. She gave
relevance to a lot
> of phylogenetic and morphological research. Hypotheses exist to be tested,
and hers
> were tested and largely rejected.  Arthropods are monophyletic, centipedes
try to
> wiggle when they run, spiders use hydraulic pressure for locomotion,
millipedes and
> centipedes got longer during evolution not shorter, xiphosurans don't chew
the way
> she thought, hexapod legs are not primitively uniramous and their jaws are
not
> "whole limbs." The edifice was so grand that people still marvel at it.
But grandiosity
> should not be mistaken for veracity.
>
> 3. I think it is reasonable to say that "arthropodization" of the dorsal
surface and
> appendages of extant arthropods occurred once, although stabilization in
podomeres
> did not occur until long after arthropodization.  Arthropodization of the
ventral surface
> is another story. Sclerotization and consolidation of ventral structures
occurred many
> times independently in many different ways; all sorts of combinations of
appendages
> and the body wall.  Yet, tergites seem to have pretty much the same
organization
> throughout the extant arthropods.
>
> 4. The idea that arthropods were primitively bivalved is also a hypothesis
to be
> tested. My impression at the moment, though, is that it doesn't really
explain anything
> and, in fact, complicates the issue unnecessarily. Based on the
evolutionary
> tendencies noted in Point 3, I would think that a trilobite-like grade of
organization
> (extensive dorsal sclerotization, soft ventral cuticle) is an adequate
model for the
> ancestral arthropod. But it is all speculation.
>
> For what it's worth.
> Jeff ShultzJeffrey W. Shultz
> Membership Secretary, American Arachnological Society
> Dept of Entomology, Univ of Maryland
> College Park, MD 20742
> Voice: (301) 405-7519, Fax: (301) 314-9290
>