[Taxacom] No more whinging and whining?

Michael Heads michael.heads at yahoo.com
Wed Feb 1 15:48:01 CST 2012


Hi Karl,
 
The point is that Hawaiian endemics could have evolved on former high islands such as the Line Islands and Musicians Seamounts and colonized the Hawaiian group before their original homes subsided. Thus they did not necessarily disperse from Asia or America, either directly or by island hopping. This is not my idea - Elwood Zimmerman suggested it for the Lines in the 1940s (the fact that the Musicians include guyots was only discovered a few years ago). It's strange that the idea has been so neglected, given that Zimmerman had such a high profile as an authority on Hawaiian insects.

Ecologists use 'long distance dispersal' to refer to an observed process of simple movement. Biogeographers use the term to refer to a mode of speciation. Ordinary ecological dispersal leading to range expanson may indeed only happen in a group once in 20 million years or whatever, as you suggest.  

Michael Heads 
 
Wellington, New Zealand.


My papers on biogeography: http://tiny.cc/HeadsPubs
My new book 'Molecular Panbiogeography of the Tropics': http://tiny.cc/MolPanbio



________________________________
 From: Karl Magnacca <kmagnacca at wesleyan.edu>
To: taxacom at mailman.nhm.ku.edu 
Sent: Thursday, 2 February 2012 9:00 AM
Subject: Re: [Taxacom] No more whinging and whining?
  
John Grehan wrote:
> Also, perhaps this book will make it more difficult for
> Hawaiians (the biogeographers) to keep up the pretence that there
> is no possible alternative to their dispersalist model for the
> islands' biota.

Not really.  The Chapter 1 excerpt makes it clear (in the section
"Island biogeography with metapopulations and without founders")
that Heads' case rests on including plant dispersal among oceanic
islands separated by hundreds of miles under his category of
"ordinary movement, seen every day".  Somehow, in panbiogeographers'
minds, events that happen every few thousand years can't happen over
longer distances every few tens or hundreds of thousand years.

Another interesting contrast of quotes:
"Puritans of all sorts (whether Oliver Cromwell or Louis XIV) cannot
stand anyone having a different view from themselves. The inflexible
schemes of these great simplifiers, levellers, and systematizers can
hold up progress for decades. In contrast, geologists (Chamberlin,
1890 reprinted 1965) and now molecular biologists (Hickerson et al.,
2010) cite the method of 'multiple working hypotheses'."

versus:

"Normal ecological movement and range expansion, along with other
kinds of 'dispersal' such as daily and annual migrations, are
accepted here; long distance dispersal/founder speciation is not."

Granted, what most people would call long distance dispersal is
somehow jammed under "normal" dispersal, but still...

> (I call it a 'pretence' because they know darned well that there
> is an alternative).

Wishful thinking is not a viable alternative.

Karl


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