[Taxacom] Hypothesis: How Nothofagus rafted to New Zealand
rjensen at saintmarys.edu
rjensen at saintmarys.edu
Tue Dec 26 18:01:21 CST 2006
"Nothofagus can not establish without its symbiotic fungi... nor can any of the other Fagacaeae for that matter."
If this is true, then how is it that oak (Fagaceae, Quercus) acorns and beech (Fagaceae, Fagus) nuts can be dispersed for kilometers (e.g., by jays) and successfully establish or, in the hands of humans, be transported to different continents and be successfully grown? Are you suggesting that the mycorrhizal fungi are always carried with the nuts, or that they occur universally and are just waiting for the acorn or beech nut to arrive?
Department of Biology
Saint Mary's College
Notre Dame, IN 46556
----- Original Message -----
From: buyck at mnhn.fr
Date: Tuesday, December 26, 2006 1:40 pm
Subject: 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 ...
> 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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