[Taxacom] almost unbelievable (advisory)

[Richard Pyle]

Hi John,

I've been careful to dodge this particular/recurring [pan]bio[geography] discussion, in large part because, well, the discussion seems so "terrestrial" in nature.  But I'm going to stick my neck out on a  limb here, and ask you two specific questions:

1) Do you think your assertions concerning miraculous assumptions of chance dispersal for the origin of allopatry apply to marine organisms as much as they do to terrestrial organisms?

And

2) Does 1966 (over half a century ago, mind you) really count as "modern" in the context of biogeography? Especially when you consider that the theory of Plate Tectonics didn't really start to become accepted widely until a series of papers published around 1965-1967.

I really don't want to start a debate (and I will not engage in one), but I'm waiting for a server to update some software before I can get back to my real job, so I figured I'd take a short break from that to understand your position a little better.

Thanks, and Aloha,
Rich

Richard L. Pyle, PhD
Senior Curator of Ichthyology | Database Coordinator
Bernice Pauahi Bishop Museum
1525 Bernice Street, Honolulu, HI 96817-2704
Office: (808) 848-4115;  Fax: (808) 847-8252
eMail: deepreef at bishopmuseum.org
BishopMuseum.org
Our Mission: Bishop Museum inspires our community and visitors through the exploration and celebration of the extraordinary history, culture, and environment of Hawaiʻi and the Pacific.

> -----Original Message-----
> From: Taxacom <taxacom-bounces at mailman.nhm.ku.edu> On Behalf Of
> John Grehan via Taxacom
> Sent: Tuesday, May 19, 2020 2:04 PM
> To: taxacom <taxacom at mailman.nhm.ku.edu>
> Subject: [Taxacom] almost unbelievable (advisory)
> 
> Dear colleagues,
> 
> Please do not read any further if biogeographic differences of perspective or
> critiques are uncomfortable for you.
> 
> As has been documented in the literature, the assumption of chance
> dispersal for the origin of allopatry periodically generates 'miracles' and
> 'mysteries' in the very words of the various authors. Despite this leaning
> towards mysticism, faith in chance dispersal continues to be well
> entrenched, and in recent decades bolstered by the charade of fossil
> calibrated divergence estimates. An addition to this mysticism comes from
> Carlquist (1966) in his exposition on long-distance dispersal (Q Rev. Biol.
> 41) where he declares “A clear understanding of long-distance dispersal is
> essential to an understanding of evolutionary trends on oceanic islands,
> because immigrant patterns are different from relict patterns.” All very well,
> until he runs into the land snail genera Tornatellides, Elasmias, and Partula.
> He describes these as having “almost unbelievable distributions”.
> Almost, but not quite it would seem. He recognizes that these distributions
> would suggest “a kind of relictism” but he ignores this because “islands they
> occupy are doubtless relatively recent in geological terms”.
> 
> What Carlquist shows here is an inability to rethink his assumptions, even
> when the distribution involved is “almost unbelievable”. The distribution is
> unbelievable because it does not fit with the theory, and rather than throw
> the theory out the data is just ignored. No matter how unbelievable, the
> distributions still arose by long-distance chance, even though “further
> observational and, if possible, experimental evidence is needed to
> demonstrate the nature and causes of 'incompetent' in insular species.” As
> with the medical sciences that use pejorative terms such as 'incompetent'
> to describe medical defects (all to often in reference to female anatomy), so
> to in biogeography are some taxa downgraded to incompetent. This is the
> world of 'truth' (as determined by authority) over 'fact'. And of course it is
> not as if Carlquist was without alternative possibilities as had already been
> made abundantly clear by Croizat and confirmed in great detail in recent
> literature. Chance dispersal becomes an excuse for anything and everything
> according to whim rather than evidence, and therefore easily slides into a
> world of 'science' where miracles, mysteries, and the unbelievable are quite
> believable indeed. And this is supposed to be modern science?
> 
> John Grehan
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