[Taxacom] Nothofagus (Chile-New Zealand)

John Grehan jgrehan at sciencebuff.org
Mon Jul 26 12:40:53 CDT 2010


Invoking or imagining 'rare' or common dispersal events does not add anything either way. Rare or common, the fact that trans-Pacific Nothofagus sub genera have vicariant main massings makes such imaginings unnecessary.

The NZ and Australian genus is Metacrias. I do not know the S American taxa.

John

-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Kenneth Kinman
Sent: Monday, July 26, 2010 12:59 PM
To: taxacom at mailman.nhm.ku.edu
Subject: [Taxacom] Nothofagus (Chile-New Zealand)

Hi Bart,
       Well, the hyphal sheath is on the outside of the root, but the
Hartig Net penetrates into the root between the epidermal and cortical
cells.  And besides, if you had a number of Nothofagus trees tangled
together forming an island raft, the roots of some of those trees could
easily be sticking upward and remain relatively high and dry.       
         -------Ken Kinman         
P.S.  And John, I did not say Nothofagus was floating all over the
place.  I am talking about rare events, which might seem unlikely, but
given millions of years of earthquakes and landslides, this kind of
rafting of whole Nothofagus trees could have eventually succeeded in a
long transocean dispersal event (in addition to possible earlier
vicariance events).  It isn't necessarily just one or the other, which
might explain why it continues to be debated.  And what moth genus were
you referring to?  I don't know if its distribution is from vicariance
or dispersal, but I can imagine  a cocoon full of moth eggs (or larvae)
being attached to a branch of trees rafting across the south Pacific.
But you can make all the jokes you want.  Doesn't bother me.                
----------------------------------------------------
buyck at mnhn.fr wrote:
       The fungal component would also favour a vicariance rather than
dispersal.... ectomycorrhiza, as the name implies, are not 'in' but
'outside' the fine roots of the tree forming a sheet of fungal tissue
around it. I can not imagine that the fungus would survive a journey  in
salty water or that fungal spores and germinating nothofagus seeds
would arrive exactly in the same spot and germinate so close to each
other that they can enter in symbiosis immediately after germination,
because this is what needs to happen. Driftwood would not disperse the
symbiosis, and a rafting hypothesis should at least have to imply a
'small island bearing part of the vegetation'. 
bart
 
Quoting John Grehan <jgrehan at sciencebuff.org>: 
> The whole of the question of dispersal is moot. Nothofagus >subgenera  
>  have vicariant main massings which suggests that their >original   
> distributions were also vicariant and therefore fragments >of an   
> already widespread ancestor. If Nothofagus was just >floating around   
> all over the place there would not be this distinctive >pattern. 
> 
> John Grehan 
> 
> -----Original Message----- 
> From: taxacom-bounces at mailman.nhm.ku.edu   
> [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf >Of Kenneth   
> Kinman 
> Sent: Monday, July 26, 2010 10:33 AM 
> To: taxacom at mailman.nhm.ku.edu 
> Subject: [Taxacom] Nothofagus (Chile-New Zealand >distributions) 
> 
>  Dear All, 
>         Question:  If a large Nothofagus tree (with 
> ripening fruit attached), or an island-like clump of a >number of such 
> trees, floated in fast-moving currents from Chile to New >Zealand,
would 
> some of the ectomycorrhizae in their roots survive the >journey?  If
so, 
> such dispersal of whole trees would preserve the >symbiosis. The
fruits 
> release their seeds and the fungus (or its spores) is also >there to 
> continue the symbiosis in New Zealand.  Nothofagus >driftwood is known
to 
> have floated from South America to Tasmania, so the >shorter trip to
New 
> Zealand would presumably be an even less rare event. 
>              --------Ken 
> 
> ---------------------------------------------- 
> buyck at mnhn.fr wrote: 
> Dear taxacom-botanists, 
> There is one element missing in the discussion of >Nothofagus and it 
> seems very essential to me : Nothofagus is an obligatory >symbiotic
tree 
> with specific terrestrial, ectomycorrhizal fungi. Seed >dispersal over 
> long distances may have happened and even germination, but >subsequent 
> development of the plant is very unlikely without the >specific fungal 
> symbionts being present. You can not discuss the dispersal >of a 
> symbiosis and completely ignore the evolutionary history >of (one or
more 
> of) the implicated partner(s). One publication that >briefly discusses 
> this element is Pirozynski KA. 1983. Pacific >Mycogeography: an 
> appraisal. Australian. Journal of Botany Supplementary >Series 10: 
> 137-159 
> bart 
> 
> 


_______________________________________________

Taxacom Mailing List
Taxacom at mailman.nhm.ku.edu
http://mailman.nhm.ku.edu/mailman/listinfo/taxacom

The Taxacom archive going back to 1992 may be searched with either of these methods:

(1) http://taxacom.markmail.org

Or (2) a Google search specified as:  site:mailman.nhm.ku.edu/pipermail/taxacom  your search terms here




More information about the Taxacom mailing list