[Taxacom] Examples for Eurasian-Australian distribution

John Grehan jgrehan at sciencebuff.org
Thu Jul 22 07:36:33 CDT 2010


I'm not sure what there is not to understand by my statement
"Distributions involving Europe, Australia, and China are innumerable,
with all manner of variants insofar as the precise range of each taxon
and nature of distributional disjunctions. Perhaps more interesting is
what are the sister taxa and what is their distribution?"

Yes, if one is looking for a group comprising three disjunct
distributions each within 'Europe" (not defined), 'China'( what is that?
- does it include Tibet or Taiwan), and 'Australia' (including
what?)there may be lees than more, but there are innumerable
distributions involving those three parts of the world. Each of these
areas are biogeographically meaningless - they are all geopolitical
units so they have no necessary biogeographic significance. As I said in
my original posting, it might be more interesting to know the
distribution of closely related taxa.

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: Wednesday, July 21, 2010 9:04 PM
To: taxacom at mailman.nhm.ku.edu
Subject: [Taxacom] Examples for Eurasian-Australian distribution

Hi Oliver,
      I don't really understand John's response that there are
"innumerable" such cases.  My understanding of your question would be
cases where a taxon has a disjunct distribution in Europe, China, and
Australia, but NOT elsewhere.  If so, such cases would probably be
relatively small in number.  The European species of Hygrobia is
apparently also found in North Africa, which might tend to restrict such
cases even further.   Off hand, I don't know of any other such cases,
but I will give it more thought.             
      Anyway, I would agree with you that this distribution is not the
result of recent dispersal.  Since Hygrobia is a relatively primitive
taxon, it most likely had a wider distribution in the past and many
intermediate populations of Hygrobia (species or subspecies) simply went
extinct due to (1) competition with certain (presumably more derived)
taxa, and/or (2) loss of habitat which offered their particular
requirements.  I would also add that it is perhaps possible that some
intermediate species still exist, especially in southeastern Asia, which
have simply not yet been discovered.  
          ---------Cheers,
                           Ken
------------------------------------------------------------
Oliver Hawlitschek wrote:
Dear all, 
I have a biogeographical question: the aquatic beetle genus Hygrobia
(Dytiscoidea) is present with one species in Europe, one in China and
four in Australia. 
Does anybody know any other group of organisms showing a similar
distribution? Probably, it is not the result of recent dispersal. 
Thanks 
Oliver Hawlitschek 


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