[Taxacom] almost unbelievable (advisory)

Tue May 19 21:42:01 CDT 2020

Thanks, John – but again your assertions seem to have much more relevance to terrestrial organisms, than oceanic/marine ones (we have both in the Pacific, and it’s not always clear which ones you are referring to when you refer to “taxa in the Pacific”).  In the marine realm, where allopatry by dispersal has probably played a much larger role than allopatry by vicariance. So… “geological influence” on patterns of allopatry in marine species?  Sure!  Absolutely.  Geological dominance?  Maybe not so much.

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

 <http://hbs.bishopmuseum.org/staff/pylerichard.html> 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.

From: John Grehan <calabar.john at gmail.com> 
Sent: Tuesday, May 19, 2020 2:59 PM
To: Richard Pyle <deepreef at bishopmuseum.org>
Cc: taxacom <taxacom at mailman.nhm.ku.edu>
Subject: Re: [Taxacom] almost unbelievable (advisory)

Just to clarify, I am not arguing non-dispersal vs dispersal. Both apply in vicariance. Dispersal is an ecological process that is responsible for the range of a species. So dispersal is essential for the origin of the ancestral range. Allopatry occurs by vicariance which is divergence within the ancestral range and so does not require range expansion. So, for the Pacific, the biogeographic evidence shows that there are allopatric distributions that are consistent with origin from widespread ancestral ranges rather than sequential dispersal between differentiated taxa. And there is plenty of geological evidence in reputable geological journals by a range of geologists that support a geological influence on the ancestral ranges and subsequent vicariance events. The dispersal capabilities of taxa in the Pacific are responsible for their persistence, just as dispersal capabilities are responsible for the persistence of taxa on continental landscapes.

John Grehan

On Tue, May 19, 2020 at 8:47 PM Richard Pyle <deepreef at bishopmuseum.org <mailto:deepreef at bishopmuseum.org> > wrote:

Thanks, John.  I don’t think anyone seriously denies that there are geographic structures in distribution patterns of marine organisms, nor does anyone deny that vicariance plays an important role in some cases (see: Panama, Isthmus of).  But in marine systems (especially out here in the big, wide Pacific), it’s often the proponents of non-dispersal explanations of distribution patterns (as opposed to explanations rooted in semi-chance dispersal) who seem to be the ones relying on miracles amid their assumptions.

Understood on the context of “modern” – thanks!

And same to you for staying safe!  We out here in Hawaii seem to have successfully dodged the serious infection rates and associated consequences rather effectively. And, I personally am doing well, and except for occasional software updates (that seem to take longer than they really should), I’m finding myself to be far more productive working from home than I had been prior to the pandemic.

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 <mailto:deepreef at bishopmuseum.org> 

 <http://hbs.bishopmuseum.org/staff/pylerichard.html> 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.

From: John Grehan <calabar.john at gmail.com <mailto:calabar.john at gmail.com> > 
Sent: Tuesday, May 19, 2020 2:36 PM
To: Richard Pyle <deepreef at bishopmuseum.org <mailto:deepreef at bishopmuseum.org> >
Cc: taxacom <taxacom at mailman.nhm.ku.edu <mailto:taxacom at mailman.nhm.ku.edu> >
Subject: Re: [Taxacom] almost unbelievable (advisory)

Hi Rich,

All very reasonable 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?

Yes. Just as allopatry occurs in birds which fly, so too does allopatry occur in marine organisms. Like aerial and terrestrial organisms, some are widespread, some are not. But there are certainly numerous examples of a geographic structure (sometimes much to the surprise of researchers) in marine taxa. Examples are covered in various publications by Heads. This geographic substructuring has often been found through molecular studies where previously morphological studies suggested very widespread amorphous species.

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.

Modern in the sense that appeals to miracles and mysteries are still made in recent times. Agreed, Carlquist was further back, but the same outlook prevails. Plate tectonics was not necessary to take a different approach (Croizat's findings came before plate tectonic theory provided corroborating geology), and most biogeographers simply pasted their centers of origin and chance dispersal theories onto the new tectonic geography (if they thought their taxon was old enough).

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.

No worries. Happy to clarify as needed. I just keep bringing these matters to attention for those interested - regardless of their particular perspectives for or against.

And to everyone, whether for or against these posts (hence the warning at the beginning as I know the subject is irritating [or I am irritating :] to some), best wishes for staying safe as possible at this time.

John Grehan

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On Tue, May 19, 2020 at 8:18 PM Richard Pyle <deepreef at bishopmuseum.org <mailto:deepreef at bishopmuseum.org> > wrote:

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 <mailto: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 <mailto: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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> Nurturing nuance while assaulting ambiguity for about 33 years, 1987-2020.