[Taxacom] [Biogeography Portal] Re: Hypothesis: How Nothofagus rafted to New Zealand

[John Grehan]

This is a great point, and although I did not even think of it, a mycological colleague also just mentioned it to me off list. It just adds to the point that things get tricky when means of dispersal are thought of as a property only of the organism rather than the ecological context created by the organism and the environment. Interestingly, my colleague mentioned some trans-Pacific relationships for fungi he was working on, including some that may be associated with Nothofagus.

John Grehan




> -----Original Message-----
> From: buyck at mnhn.fr [mailto:buyck at mnhn.fr]
> Sent: Tuesday, December 26, 2006 1:40 PM
> To: Ken Kinman
> Cc: taxacom at mailman.nhm.ku.edu; biogeography at bohm.snv.jussieu.fr
> Subject: [Biogeography Portal] Re: [Taxacom] Hypothesis: How Nothofagus
> rafted to New Zealand
> 
> Hi to all...I have been following this discussion with a lot of interest
> but
> since I am not at work, I don't know if this mail will reach the Taxacom
> list.
> 
> it seems to me that you all forget one thing. Nothofagus has no roots...it
> has
> mycorrhizas..that is : it is obligatory symbiotic with certain groups of
> basidiomycetes (Fungi) that are mostly very specific in their
> relationship.
> Discussing Nothofagus without considering the whole functional entity
> (fungus +
> host) is discussing artefacts....Nothofagus can not establish without its
> symbiotic fungi... nor can any of the other Fagacaeae for that matter.
> Botanists should consult mycology much more often....and although Cyttaria
> has
> been mentioned, a parasite can be transfered by birds ....root symbionts
> can
> not however.
> 
> Considering the whole entity considerably narrows down the dispersal
> possibilities....human dispersal can be ruled out safely....since it does
> not
> allow for the gradual development of specific fungal symbionts for the
> individual Nothofagus species....and rafting seems the only acceptable
> dispersal hypothesis left if vicariance is not the explanation (birds can
> not
> bring the symbionts across)
> 
> Unfortunately, we don't know enough about the fungi for the moment to
> propose a
> well supported hypothesis for Nothofagus, but this is one of my fields of
> investigation for the moment. One author that discussed the topic more
> than 20
> years ago is Pirozynski (1983 if I remember correctly).
> 
> So the brainstorming part is not entirely over yet ...
> 
> bart
> 
> 
> 
> Selon Ken Kinman <kinman at hotmail.com>:
> 
> > John Grehan wrote:
> >     >Ken's basic methodology seems to be imagining that vicariance is
> > >falsified, then imagining dispersal is the only probable alternative.
> No
> > >wonder historical geologists don't take biogeography seriously.
> > *********************************
> > John,
> >     Actually that is just the first step in my methodology.
> Brainstorming
> > all the different possible scenarios, and then seeing whether lines of
> > evidence from other organisms fits any of those scenarios better.  If
> lots
> > of organisms show similar patterns supporting a dispersal scenario and
> > they contradict a vicariance scenario, then I would say my intuition was
> > correct.
> >
> >      If those lines of evidence fit a vicariance scenario, then I'll cry
> > "uncle" and congratulate John Grehan on his insight.  Vicariance almost
> > certainly played a major role in the evolution of the Nothofagus faunas
> of
> > South America, Antarctica, and Australia, but the relatively early
> > separation of New Zealand makes me strongly suspect Cenozoic dispersal
> from
> > Tasmania for Nothofagus and its parasites.  We shall see.  The
> brainstorming
> > part is over, and now the more difficult task of gathering various lines
> of
> > evidence, both morphological and molecular (and seeing if they
> contradict or
> > support vicariance).
> >     ------Cheers,
> >               Ken Kinman
> > P.S.  I am still in the brainstorming stage on the question of the
> northern
> > Nothofagus group (New Guinea, etc.).  It has been suggested that lack of
> > Cyttaria might indicate it split off first from other Nothofagus groups,
> in
> > contrast to other evidence indicating it was more phylogenetically
> derived.
> > I think I'll keep my "imaginings" on that subject to myself for now (as
> I am
> > sure some people probably think this thread has already gone on too
> long).
> > :-)
> >
> > _________________________________________________________________
> > Dave vs. Carl: The Insignificant Championship Series.  Who will win?
> >
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> >
> >
> >
> 
>