[Taxacom] Examples for Eurasian-Australian distribution

Stephen Thorpe stephen_thorpe at yahoo.co.nz
Thu Jul 22 16:06:42 CDT 2010


not as curious as the related family Aspidytidae ...




________________________________
From: Jason Mate <jfmate at hotmail.com>
To: Taxacom <taxacom at mailman.nhm.ku.edu>
Sent: Fri, 23 July, 2010 4:04:50 AM
Subject: Re: [Taxacom] Examples for Eurasian-Australian distribution


Because it is a fairly old taxon; widely dispersed but species-poor (only 5 
species); and with a very common habitat (stagnant water). So, if it spread so 
widely why is it absent from so much potentially optimum habitat? It is curious.
Jason


> Date: Thu, 22 Jul 2010 08:38:15 -0400
> From: jgrehan at sciencebuff.org
> To: taxacom at mailman.nhm.ku.edu
> Subject: Re: [Taxacom] Examples for Eurasian-Australian distribution
> 
> Why should the absence of Hygrobia from all the rest of the world be a
> problem since all taxa are absent from somewhere eles.
> 
> John Grehan
> 
> -----Original Message-----
> From: taxacom-bounces at mailman.nhm.ku.edu
> [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Oliver
> Hawlitschek
> Sent: Thursday, July 22, 2010 4:12 AM
> To: taxacom at mailman.nhm.ku.edu
> Subject: Re: [Taxacom] Examples for Eurasian-Australian distribution
> 
> As stated by Ken, our problem is in fact the current absence of Hygrobia
> from all the rest of the world, which probably means that today's
> Hygrobia species show a relic distribution. Of course there may be other
> species yet to be found. I should note that the Chinese Hygrobia davidi
> Bedel, 1883 is known from the type specimen only and has never been
> found afterwards.
> 
> In: Benton, M.J. (1993) The fossil record 2, a Miocene fossil of
> Hygrobia is mentioned, but with no further information. Does anybody
> know more about this?
> 
> Best regards
> 
> 
> Oliver
> 
> 
> 
> 
> -------- Original-Nachricht --------
> > Datum: Wed, 21 Jul 2010 20:03:31 -0500
> > Von: kennethkinman at webtv.net
> > An: taxacom at mailman.nhm.ku.edu
> > Betreff: [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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