[Taxacom] Vicariated Hawaii [was Seed plants of Fiji]

[John Grehan]

Neal,

You make some pertinent points. The trouble with basing biogeography on
geological theories about availability or lack thereof emergent islands
throughout is that the geological theories are just that - theories.
They may seem to be very good theories - i.e. all the current geological
evidence, or its interpretation leads to a consensus view. However,
biogeography may represent an independent source of evidence that could
call such theories into question. 

For example, the connection between Hawaii and Tahiti may be correlated
with the geological theory suggesting some of the Hawaiian chain
originated in the south. But then some would argue that the island
integration was never close enough to allow direct terrestrial or
shallow marine transfer. Perhaps so, but the meta-population theory does
not require that such organisms cannot have the opportunity to move over
water through their means of dispersal. The vicariism just means that
the process was local rather than regional. 

As to what is the final answer to the pacific, I don't know. Perhaps it
is an expanding earth, mobile micro-continents, upraised basaltic
plateaus, or mobile island arcs. It is that uncertainty which makes the
Pacific of particular interest - at least to me. Perhaps rather than
subordinating biogeography to the Pacific Ocean model biogeographers
could be in a position to really investigate alternative possibilities.
If the Pacific has always been an open oceanic ocean then Croizat was
somehow gifted by the gods to get it right about the composite tectonics
of the Americas. There is a real anomaly for you.

John Grehan


> -----Original Message-----
> From: Neal Evenhuis [mailto:neale at bishopmuseum.org]
> Sent: Wednesday, November 15, 2006 7:11 PM
> To: John Grehan
> Cc: Karl Magnacca; taxacom at mailman.nhm.ku.edu
> Subject: Re: [Taxacom] Vicariated Hawaii [was Seed plants of Fiji]
> 
> At 5:36 PM -0500 11/15/06, John Grehan wrote:
> >What is the Lemuria remark supposed to mean? Does it mean that you
have
> >already decided the answer to the Pacific that does not allow for a
> >vicariant origin?
> 
> John:
> I read Karl's inclusion of Lemuria in his reply to you as a
> "question", not a "remark". If not Lemuria, then what about Mu? or
> the Darwin Rise? East Pacific Rise? A comet or asteroid? These are
> all questions, not remarks. And we need answers to those questions.
> All those questions source areas have been postulated (although I
> have to admit it will be a stretch to pull out the asteroid reference
> but I think I have it somewhere).
> 
> So, I'm curious too. And I would bet dollars to donuts that a lot of
> folks doing Hawaiian biology (whether we live in Hawaii [e.g., me],
> have lived in Hawaii [e.g., Karl], or wish to live in Hawaii [e.g.,
> Tom]) would be thrilled to know where our biota vicariated from.
> 
> However, maybe the inference is that one has to assume a closed
> Pacific (a la McCarthy) in the Late Cretaceous and that the portion
> of the Hawaiian chain that was then emerged [and led to the current
> Hawaiian biota on all of the emergent islands] derived its fauna from
> a formerly zippered North America and East Asia, with the Hawaiian
> chain cozily snuggled between the two.
> 
> But then one has to explain what happened to that fauna about 50 mya
> when the Pacific was no longer "closed" (a la McCarthy) and the
> geologic evidence shows that there were no emergent islands in the
> Hawaiian chain, the previous ones having been submerged through
> island erosion and subsidence and the Hawaiian chain [and its biota
> now without land, treading water really fast, and pretty much
> freaking out] waiting on the next island to reach the surface.
> 
> I've read Heads's article and can't find the answer there.
> 
> In the famous words of Ben Stein: "Anybody? Anybody?"
> 
> Neal