[Taxacom] Long-distance oceanic dispersal (rafting) of Nothofagus species
John Grehan
calabar.john at gmail.com
Sun Jun 3 20:18:50 CDT 2018
Stephen,
While there is no direct geological evidence of connection to any other
landmass (in the form of a land bridge) the region has supported large
igneous plateaus that would have supported a terrestrial biota, some of
which could have been stranded on the hotspot (and other hotspots such as
the Galapagos).
The 'discordant' character has no necessary significance. If a continent
is drowned other than for ephemeral volcanoes then you would expect that
result, for example (not saying this for Hawaii).
If you read Heads on Hawaii I would be happy to respond to any specific
points you raise.
John Grehan
On Sun, Jun 3, 2018 at 9:13 PM, Stephen Thorpe <stephen_thorpe at yahoo.co.nz>
wrote:
> I don't know all the details, but the basic idea surely takes into
> account:
> (1) The geological history of the islands (were they ever connected to
> another landmass in a possible vicariant relationship?)
> (2) The biota as a whole is discordant with that of any other landmass,
> with many "gaps" and consequent radiation of a few lineages into the many
> "gaps", in exactly the way that would be expected from chance dispersal.
>
> 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, 1:00 PM
>
> 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:ki n
>
> 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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>
> >> Assaulting Ambiguity for 31 Some
>
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>
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> >>
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> >>
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> 1987-2018.
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> >>
>
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> >
>
>
>
> >
>
>
>
> >
>
>
>
> >
>
>
>
> --
>
>
>
> > -So many mites, so little time!
>
>
>
> > Barry M. OConnor
>
>
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> Professor & Curator
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> Ecology & Evolutionary Biology
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> Research Museums Center
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> > University of
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> Michigan phone:
> 734-763-4354
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> > 3600 Varsity Drive
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> >
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> <https://maps.google.com/?q=
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> >
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> fax:
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> 734-763-4080
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>
>
> > Ann Arbor, MI 48108-2228
>
>
>
> e-mail: bmoc at umich.edu
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