[Taxacom] Dispersal clarifications: frogs on an oceanic islands

[John Grehan]

With all due respect, I had to laugh when I read Ken equating
unreasonableness in panbiogeography with cladistics. Croizat, as a
severe critic of cladistics would be rolling over in his grave.

Ken's appeal to the 'reasonable' criterion of science is a repeated
theme over the years. It boils down to what Ken believes being
reasonable and what he does not is not. Of course reasonableness has no
scientific merit whatsoever. Evolution never took place anticipating
what Ken might later think of as being reasonable. If it is unreasonable
to stick to the facts - such as recognizing fossil ages as minimal, and
derived molecular clock estimates also as minimal - then I will stick to
being unreasonable.

Science is, by its very nature, unreasonable - at least any progressive
science where one has to call into question accepted views which by
their nature may be considered reasonable. Barbara McClintock was
clearly regarded as unreasonable (and worse) for her genetic views, not
that this made any difference to the scientific veracity of her work. A
colleague of mine believes the fossil records points to evidence
supporting his contention that some hominids lived primarily in trees
until as late as 60,000 years ago. This has no acceptance whatsoever
among paleoanthropologists so my colleague is in no doubt being
perfectly unreasonable in sticking to his theory.  

Panbiogeography may be unreasonable in regarding an understanding of
locality as a fundamental precondition to any adequate analysis of the
patterns and processes of evolutionary change. Whether or not that may
be considered 'excessive' and 'unreasonable' for a dispersalist does not
matter one little bit.

John Grehan
Society of the unreasonable

-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu
[mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Kenneth Kinman
Sent: Monday, June 13, 2011 10:36 PM
To: taxacom at mailman.nhm.ku.edu
Subject: [Taxacom] Dispersal clarifications: frogs on an oceanic islands

Hi David,
      I totally agree. Organisms both disperse and experience vicariant
events as well.  And I would only add the obvious, that not only will
different species have a different balance, but also various higher taxa
will as well.     
       But my experience is that panbiogeographers tend to skew that
balance in favor of vicariance in too many cases.  Panbiogeography sort
of reminds me of strict cladism in that its adherents can tend to go
overboard, although I must quickly add that strict cladism has done far
more damage than panbiogeography ever could.  Not that cladistics (well
done) hasn't done a lot of good, but strict cladism has also done a lot
of harm (far too much of a good thing, so too speak).  Likewise
panbiogeography can sometimes go overboard as well (especially when it
has a knee-jerk reaction against perfectly reasonable dispersal
hypotheses, like Nile crocs founding the American clade).  But the
problems caused by excessive panbiogeography is just a minor nuisance
compared to problems caused by strict cladism during the same time frame
(latter decades of the 20th Century). 
           -----------Ken           
----------------------------------------------------------
David Campbell wrote: 
     "Dispersal" involves multiple factors.  Most mammals are fairly
good locomotors, but many are somewhat large for riding on the average
floating or flying object and the high metabolism limits how long they
can float or swim without food.  Non-swimming mollusks are generally
slow but good at riding and at estivating. Of course, ability to survive
upon arrival is also an issue. 
Organisms disperse and they experience vicariant events.  Different
species will have a different balance.


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