[Taxacom] Long-distance oceanic dispersal (rafting) of Nothofagus species
Stephen Thorpe
stephen_thorpe at yahoo.co.nz
Sun Jun 3 20:13:00 CDT 2018
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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>
>
>
>
--
> -So many mites, so little time!
> Barry M. OConnor
>
Professor & Curator
> Department of
Ecology & Evolutionary Biology
>
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