[Taxacom] Scale insects and Nothofagus (dispersed together)

John Grehan jgrehan at sciencebuff.org
Fri Jul 30 13:05:09 CDT 2010


Ken,

You might try to take a critical look at papers before asserting their
claims. The abstract states: "Australian and New Zealand species of
Madarococcus form a monophyletic group to the exclusion of the South
American species, suggesting that long-distance dispersal has played an
important role in shaping the distributions of both the
Nothofagus-feeding felt scales and their hosts."

So the obvious question is why does such a relationship 'suggest'
long-distance dispersal?

I don't have access to the original paper, but I pretty much anticipate
what the claim is based on and why it is not supported by the actual
evidence.

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: Friday, July 30, 2010 12:34 PM
To: taxacom at mailman.nhm.ku.edu
Subject: [Taxacom] Scale insects and Nothofagus (dispersed together)

Hi John and others,
      Well, the first insect pest (on Nothofagus) that I looked at this
morning actually indicates that felt scale insects and Nothofagus not
only evolved together, but that both groups show the same pattern of
trans-ocean dispersal between Australia and New Zealand.   The study by
Hardy et al., 2008 (see weblink below) studied the phylogeny of these
felt scale insects with both morphology AND molecular sequences, and it
was congruent with earlier studies on Nothofagus alone, indicating
trans-ocean dispersal (NOT vicariance).  Not hard to imagine lots of
these insects hitching a ride on floating Nothofagus trees between
Australia and New Zealand.    
       Whether these or other insect pests can limit the dispersal
ability of Nothofagus is another question, but an interesting one.  If
such insects can decrease plant vigor in mature trees, just think what
kind of damage they could do to young trees trying to disperse to new
territory.  Trans-ocean dispersal between Australia and New Zealand may
have taken many raftings before Nothofagus was successful in becoming
established.  Over millions of years, there could have been thousands of
such raftings, but the vast majority failed for any number of different
reasons.  But looks like it succeeded at least once, and I am not the
only one who thinks so.  
        ---------Ken                 
http://espace.library.uq.edu.au/view/UQ:171696



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