[Taxacom] North America, Central America + S.E. Asia sister taxa

Kenneth Kinman kennethkinman at webtv.net
Thu Dec 29 22:31:36 CST 2011


Hi Michael,  
        Well, that is sometimes the problem with overly-broad vicariance

explanations, since what seems to be "simple" could be a little too
"simplistic"---somewhat like "Reaganomics" and the trickle-down theory
(which actually seems to have actually favored the exact opposite,
namely an extreme and accelerating trickle-up of wealth since the Reagan

years.  Hence, the present "occupy" movement should have probably
happened over 25 years ago (but better late than never).    

       Anyway, I would not be surprised if Salvadoraceae is actually
paraphyletic with respected to Bataceae (for instance, isn't the latter
even more halotolerant than the former?).  But just for the sake of
argument, let's assume that they are actually sister groups which split
somewhere in southeastern Asia.  The original stem-group could have
easily been confined to southeastern Asia, with Salvadoraceae dispersing

west, while Bataceae dispersed east to New Guinea, then to Australia,
and from one of those across the Pacific by rafting (the longer rafting
event having been made possible by the earlier shorter jumps across
closely-spaced islands in southeastern Asia (halotolerance increasing
along the way).  

      The major difference between this and the Hemiprocnidae birds or
Kip's beetle taxa, is that they invaded the New World from Europe, while

Bataceae probably invaded in the opposite direction across the Pacific
(by whatever route one might think most likely).   In any case, "simple
vicariance" just seems too simplistic in all these cases without some
dispersal following the vicariance event which gave rise to the sister
groups.                 
           --------------Ken   
P.S.  I will have to look more closely to see if there is any evidence
that Salvadoraceae might be paraphyletic with respect to Bataceae.  In
that case, dispersal would be even more important in explaining their
evolution.         
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Mchael Heads wrote:
Hi Ken, 
  
Bataceae (trans-Pacific) are sister to Salvadoraceae (Africa and
Madagascar, India and SE Asia), so there is a Pacific group sister to an

Indian Ocean group. You can explain each one individually by a center of

origin approach, but taken together they suggest simple vicariance.  
 Michael Heads  

________________________________ 
 From: Kenneth Kinman <kennethkinman at webtv.net> 
To: taxacom at mailman.nhm.ku.edu 
Sent: Friday, 30 December 2011 4:05 PM 
Subject: Re: [Taxacom] North America, Central America + S.E. Asia sister

taxa 
 
Hi John and Don, 
      It is not surprising that there are so many such Pacific
patterns, since there are a number of different ways by which they could

have arisen, including northern Beringian dispersal, southern Antarctic
dispersal, or even direct dispersal across the Pacific (as well as even
broader original distributions undergoing severe geographic extinction 
of intermediate taxa).      
       Interestingly, any of the three mentioned below
(Enicoscolus, Pitnus, and Batis) seem to me to be good candidates for
direct dispersal across the Pacific via rafting.  Pitnus are
leaf-miners which could feed on the leaves of rafting trees, Batis
plants are a good candidate to survive on rafts since they are extremely

salt-tolerant, and even Enicoscolus larvae could easily feed on the
dying matter in such rafts. Not at all surprising that Pitnus is even
found in the Galapagos.    
               --------Ken 
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