[Taxacom] Long-distance oceanic dispersal (rafting) of Nothofagus species

[John Grehan]

What is the evidence?

John Grehan

On Sun, Jun 3, 2018 at 8:59 PM, Stephen Thorpe <stephen_thorpe at yahoo.co.nz>
wrote:

> Hawaii is a classic example of a biota derived mainly (exclusively?) by
> chance dispersal rather than vicariance, with consequent radiation of
> lineages into unoccupied niches. Makes sense to me!
>
> Stephen
>
> --------------------------------------------
> On Mon, 4/6/18, John Grehan <calabar.john at gmail.com> wrote:
>
>  Subject: Re: [Taxacom] Long-distance oceanic dispersal (rafting) of
> Nothofagus species
>  To: "Stephen Thorpe" <stephen_thorpe at yahoo.co.nz>
>  Cc: "Barry OConnor" <bmoc at umich.edu>, "taxacom at mailman.nhm.ku.edu" <
> taxacom at mailman.nhm.ku.edu>
>  Received: Monday, 4 June, 2018, 12:55 PM
>
>  Hawaii is
>  a classic example of what?
>  John Grehan
>  On Sun, Jun 3, 2018 at 8:53
>  PM, Stephen Thorpe <stephen_thorpe at yahoo.co.nz>
>  wrote:
>  Evidence
>  for long distance dispersal over vicariance must take into
>  account entire biotas, not just selected taxa. Hawaii is the
>  classic example.
>
>
>
>  Stephen
>
>
>
>  ------------------------------ --------------
>
>  On Mon, 4/6/18, John Grehan
>  <calabar.john at gmail.com>
>  wrote:
>
>
>
>   Subject: Re: [Taxacom] Long-distance oceanic dispersal
>  (rafting) of    Nothofagus species
>
>   To: "Barry OConnor" <bmoc at umich.edu>
>
>   Cc: "taxacom at mailman.nhm.ku.edu"
>  <taxacom at mailman.nhm.ku.edu>
>
>   Received: Monday, 4 June, 2018, 12:49 PM
>
>
>
>   Barry,
>
>
>
>   An answer to your question requires a bit of a
>
>   clarification about
>
>   dispersal and its
>
>   relationship to biogeographic origin of allopatric taxa
>
>   (which is what most biogeographic controversies
>
>   are about), although
>
>   probably best to read
>
>   discussion about that in a more structured account
>
>   such as you will find in Heads' books .
>
>   Dispersal as an ordinary ecological
>
>   process
>
>   is what we observe in real time. It results in survival
>  of
>
>   the
>
>   species and may result in range
>
>   expansion under particular circumstances.
>
>   Differentiation of allopatric taxa requires
>
>   isolation. If dispersal is so
>
>   pervasive as
>
>   to preclude isolation then there cannot be allopatric
>
>   differentiation. This is the tangle that
>
>   emerges when dispersal is used as
>
>   the
>
>   mechanism to explain biogeographic patterns of allopatry.
>  A
>
>   resolution
>
>   of this paradox is to view
>
>   dispersal as operative in establishing ancestral
>
>   range rather than creating isolated entities.
>
>   So seeing  *Anolis* lizard on
>
>   a raft of
>
>   hurricane debris just off a Caribbean island is
>  effectively
>
>   no
>
>   different from seeing any other organism
>
>   moving or moved about. It has
>
>   immediate
>
>   ecological significance (in terms of metapopulation
>  survival
>
>   for
>
>   example - again characterized in more
>
>   detail by Heads) but its
>
>   biogeographic role
>
>   cannot be assumed.
>
>
>
>   John
>
>   Grehan
>
>
>
>   On Sun, Jun 3, 2018
>
>   at 7:28 PM, Barry OConnor <bmoc at umich.edu>
>
>   wrote:
>
>
>
>   > I'm curious
>
>   - what is *evidence* of chance dispersal other
>  than, say,
>
>   > seeing an *Anolis* lizard on a raft of
>
>   hurricane debris just
>  off a
>
>   > Caribbean
>
>   island? - Barry
>
>   >
>
>   > On
>
>   Sun, Jun 3, 2018 at 7:08 PM, Kenneth Kinman <kinman at hotmail.com>
>
>   wrote:
>
>   >
>
>   >>
>
>   John,
>
>   >>
>
>   >>
>
>      Well, you tossing out such red herrings will not
>
>   dissuade me.
>
>   >> Including the
>
>   scientific one about frogs.  The two primitive frog
>
>   families
>
>   >> originated way back in the
>
>   Paleozoic when the world map was much different
>
>   >> (Gondwanaland still largely intact).
>
>   No long-distance dispersal
>
>   >>
>
>   necessary.  Vicariance explains that case quite
>  nicely.
>
>   Nothofagus evolved
>
>   >> much later
>
>   (after the break up Gondwana), so I don't know why
>  you
>
>   tossed
>
>   >> out that red herring.
>
>   And comparing my hypothesis to UFOs or an Act of
>
>   >> God could be interpreted as a bit
>
>   insulting.  And in your second post
>
>   >> saying that "Chance dispersal
>
>   continues to hold a very visceral appeal for
>
>   >> evolutionary biologists", seems
>
>   to indicate to me that many
>
>   >>
>
>   panbiogeographers tend to overstate the importance of
>
>   vicariance and too
>
>   >> often either
>
>   ignore or attack evidence for chance dispersal when it
>  is
>
>   >> presented.  I suspect that is what
>
>   will happen if any evidence is found to
>
>   >> support my hypothesis.  One thing is
>
>   certain---we won't find such evidence
>
>   >> if we don't look for it.
>
>   >>
>
>   >>
>
>         -------------Ken
>
>   >>
>
>   >> P.S.  Your latest comment about
>
>   "fairy tales" was a bit rude.  I don't
>
>   >> see why the explanation I put forward
>
>   and question I asked of Bart should
>
>   >>
>
>   be characterized as fairy tales.
>
>   >>
>
>   >>
>
>   >>
>
>   ______________________________ __
>
>   >>
>
>   From: John Grehan <calabar.john at gmail.com>
>
>   >> Sent: Sunday, June 3, 2018 9:46 AM
>
>   >> To: Kenneth Kinman
>
>   >> Cc: Stephen Thorpe; taxacom at mailman.nhm.ku.edu
>
>   >> Subject: Re: [Taxacom] Long-distance
>
>   oceanic dispersal (rafting) of
>
>   >>
>
>   Nothofagus species
>
>   >>
>
>   >> Ken,
>
>   >>
>
>   >> Its not a testable notion in any real
>
>   sense any more than attributing the
>
>   >>
>
>   connection to UFO's. Further, it is not an
>  'odd'
>
>   distribution, but one that
>
>   >> is very
>
>   even (meaning standard). One can invoke any number of
>
>   imaginary
>
>   >> events to toss plants and
>
>   animals from one side of the Tasman to the other,
>
>   >> or even just place them there by an
>
>   Act of God, but there is no empirical
>
>   >> imperative to do so for this any more
>
>   than imagining a tsunami to toss
>
>   >>
>
>   frogs from Vancouver to New Zealand.
>
>   >>
>
>   >> John
>
>   Grehan
>
>   >>
>
>   >> On
>
>   Sun, Jun 3, 2018 at 8:38 AM, Kenneth Kinman <kinman at hotmail.com
>
>   >> <mailto:kinman at hotmail.com>>
>
>   wrote:
>
>   >> Hi Stephen,
>
>   >>
>
>   >>       But
>
>   it could be somewhat scientifically testable if some
>
>   organisms
>
>   >> (mostly likely insects)
>
>   have the same odd distribution in New Zealand and
>
>   >> Tasmania (or adjacent Australia).  So
>
>   I am hoping that some entomologist
>
>   >>
>
>   might know of insects that fit the bill.  And if there
>  were
>
>   more than one
>
>   >> such organism, the
>
>   more likely this dispersal scenario would become.
>
>   >>
>
>   >>
>
>   And note that I cited two different Nothofagus species
>
>   groups with
>
>   >> the same odd
>
>   distribution (one in subgenus Lophozonia and the other
>  in
>
>   >> subgenus Fuscospora).  And those two
>
>   dispersals could have happened at
>
>   >>
>
>   different times.  So that already increases the
>  probability
>
>   of dispersal.
>
>   >> Anyway, at least Fred
>
>   understood what I was suggesting:
>
>   >>
>
>   http://mailman.nhm.ku.edu/
>  pipermail/taxacom/2006- December/108388.html
>
>   >>
>
>   >>
>
>   >> -----------------Ken
>
>   >>
>
>   >>
>
>   ______________________________ __
>
>   >>
>
>   From: Stephen Thorpe <stephen_thorpe at yahoo.co.nz<
>  mailto:
>
>   >> stephen_thorpe at yahoo.co.nz>>
>
>   >> Sent: Saturday, June 2, 2018 8:59
>
>   PM
>
>   >> To: Kenneth Kinman
>
>   >> Cc: taxacom at mailman.nhm.ku.edu<
>  mailto:taxacom at mailman.nhm.ku.
>  edu>
>
>   >> Subject: Re: [Taxacom] Long-distance
>
>   oceanic dispersal (rafting) of
>
>   >>
>
>   Nothofagus species
>
>   >>
>
>   >> "Could certain insects, mosses,
>
>   or other organisms have hitched a ride on
>
>   >> such a Nothofagus raft?"
>
>   >>
>
>   >> Impossible to
>
>   rule out just about anything that doesn't
>  constantly
>
>   >> require running freshwater. If it
>
>   happened during summer, there could be a
>
>   >> desiccating effect, but at other times
>
>   the amount of freshwater dampness
>
>   >>
>
>   could remain at acceptable levels.
>
>   >>
>
>   >> The problem
>
>   though, as I see it, is that these dispersion events
>  are
>
>   >> entirely random and unpredictable, so
>
>   it is hard to base much in the way of
>
>   >> science on it.
>
>   >>
>
>   >> Stephen
>
>   >>
>
>   >>
>
>   ------------------------------ --------------
>
>   >> On Sun, 3/6/18, Kenneth Kinman <kinman at hotmail.com<mailto:kin
>
>   >> man at hotmail.com>>
>
>   wrote:
>
>   >>
>
>   >>
>
>   Subject: [Taxacom] Long-distance oceanic dispersal
>  (rafting)
>
>   of
>
>   >> Nothofagus      species
>
>   >>  To: "Kenneth Kinman"
>
>   <kinman at hotmail.com<mailto:kin
>  man at hotmail.com>>
>
>   >>  Cc: "taxacom at mailman.nhm.ku.edu<
>  mailto:taxacom at mailman.nhm.ku.
>  edu>"
>
>   <
>
>   >> taxacom at mailman.nhm.ku.edu<
>  mailto:taxacom at mailman.nhm.ku.
>  edu>>
>
>   >>
>
>   >>  Received:
>
>   Sunday, 3 June, 2018, 1:51 PM
>
>   >>
>
>   >>  Hi all,
>
>   >>
>
>   >>  The recent thread got me thinking
>
>   about a debate that some
>
>   >>  of us
>
>   were having on taxacom almost 12 years ago.  Namely
>
>   >>  whether long-distance oceanic
>
>   dispersal (by rafting) was a
>
>   >>
>
>   significant factor in the geographic distribution of
>  some
>
>   >>  species of Nothofagus (sensu
>
>   lato).
>
>   >>
>
>   >>
>
>   My hypothesis was that large rafts of dislodged
>
>   Nothofagus
>
>   >>  trees (due to tsunami
>
>   or other massive flooding event) could
>
>   >>  have held some of their fruit above
>
>   the ocean surface and
>
>   >>  rafted from
>
>   Tasmania to New Zealand, where one or more  new
>
>   >>  species could evolve (due to founder
>
>   effect).  This would
>
>   >>  be a
>
>   relatively short rafting event compared to the much
>
>   >>  longer driftwood oceanic rafting
>
>   that happened from South
>
>   >>  America
>
>   to Tasmania: Barber, 1959, in the journal Nature;
>
>   >>  "Transport of Driftwood from
>
>   South America to
>
>   >>  Tasmania".
>
>   Is there other evidence that such dispersal
>
>   >>  of Nothofagus could have happened?
>
>   Could certain insects,
>
>   >>  mosses, or
>
>   other organisms have hitched a ride on such a
>
>   >>  Nothofagus raft?
>
>   >>
>
>   >>
>
>            --------------Ken Kinman
>
>   >>  http://mailman.nhm.ku.edu/
>  pipermail/taxacom/2006- December/108385.html
>
>   >>
>
>   ______________________________ _________________
>
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>   >>
>
>   >>  Nurturing Nuance while
>
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>
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>   >>
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>
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>   >>
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>   >>
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>   >
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>   >
>
>   >
>
>   >
>
>   --
>
>   > -So many mites, so little time!
>
>   > Barry M. OConnor
>
>   >
>
>   Professor  & Curator
>
>   > Department of
>
>   Ecology & Evolutionary Biology
>
>   >
>
>   Research Museums Center
>
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>
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>
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