[Taxacom] Scale insects and Nothofagus

[Kenneth Kinman]

Hi Stephen,
        Or alternatively, New Zealand did split off with one or more
primitive forms of Nothofagus, but they went extinct.  They could have
gone extinct due to various pressures, including: (1) subsidence and
shrinking habitat, and/or (2) Australian Nothofagus species later
invaded and outcompeted with them for various reasons.       
      However, these questions would not be scientifically investigated
if everybody just bought the vicariance-only argument.  So I would
disagree with John Grehan---the point is not moot and is subject to
further debate.  Like the French say, Viva la difference.       
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Stephen Thorpe wrote:

Undoubtedly, both vicariance and dispersal have played parts. We
shouldn't think of dispersal just in terms of current distances apart of
landmasses - it would have been easier in the past. For Nothofagus,
perhaps N.Z. split off first without Nothofagus, then gained it by
dispersal from Australia long enough after the Australia/South America
split to result in South America being the sister group to Australia +
N.Z. 
________________________________ 
From: Kenneth Kinman <kennethkinman at webtv.net> 
To: taxacom at mailman.nhm.ku.edu 
Sent: Mon, 2 August, 2010 11:34:47 AM 
Subject: [Taxacom] Scale insects and Nothofagus 
Hi Michael, 
      There seem to be two main reasons (perhaps there are others)
that have been put forward by those who do not think Nothofagus
distribution is totally vicariant.  One is the early date at which New
Zealand broke off of Antarctica (at least 80 million years ago), not all
that long after Nothofagus itself originated.  If vicariant, it's
Nothofagus fauna should be sister group to the rest of Nothofagus
(instead the South American fauna shows that pattern, even though South
America and Australia were still connected to Antarctica well after New
Zealand broke away).  Arguing against this with "main massings" will
probably 
cause most non-panbiogeographers to simply roll their eyes.  
      The second problem is that a totally vicariant Nothofagus
rests upon the argument that all four extant subgenera of Nothofagus
originated in the Cretaceous.  This caused problems for the totally
vicariant view when evidence was found that these four subgenera are
perhaps much younger, and that the Cretaceous subgenera were simply
convergent with extant subgenera.        Anyway, the results of
Hardy et al., 2008, now convince me that the longer-range trans-ocean
dispersal of Nothofagus between Chile and New Zealand is indeed an
unlikely (and unnecessary) event (which should make a lot of people
happy).  However, the shorter trans-ocean dispersal between Australia
and New Zealand is much more likely, and a number of researchers believe
at least one or two such dispersals are necessary to explain Nothofagus
distributions.  Congruence with the distribution of 
their felt scale insects bolstered that view (Hardy, et al., 2008). 
          
            ---------Ken Kinman             
        
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