[Taxacom] Salvadoraceae paraphyletic? (was: North America...)

[Kenneth Kinman]

Hi Michael,
        Good point.  If Azima and Batis do exclusively clade together
(in which case, there should be a lot more synapomorphies than just the
secondarily-partitioned ovary; which what I am looking for), then it
would probably be more appropriate to just transfer Azima to Family
Bataceae.  That would mean that Family Bataceae (sensu lato) and Family
Salvadoraceae (sensu stricto) probably split much further west (perhaps
in Africa).   If such a phylogeny proves to be true, at least the strict

cladists shouldn't object to that.                   
             --------------Ken                
-------------------------------------------------------------
Michael Heads wrote:     

Hi Ken, 
I don't think proposing ad hoc changes to the taxonomy to make it fit
with a biogeographic theory is very convincing. But even assuming that
Salvadoraceae is paraphyletic, if Azima (Africa - Malesia) gave rise to
Batis (Australia - America) after crossing Wallace's Line, Batis would
be nested in Azima, not sister to it. You would have to propose that
Azima is paraphyletic as well. 
Michael 
Wellington, New Zealand. 
My papers on biogeography: http://tiny.cc/HeadsPubs 
My new book 'Molecular Panbiogeography of the Tropics':
http://tiny.cc/MolPanbio 
________________________________ 
 From: Kenneth Kinman <kennethkinman at webtv.net> 
To: taxacom at mailman.nhm.ku.edu 
Sent: Monday, 2 January 2012 3:55 PM 
Subject: [Taxacom] Salvadoraceae paraphyletic? (was: North America...) 
 
Hi again Michael,              
       It seems that John thinks that my brainstorming is 
akin to creationism, rather than a search for new possibilities to
explore.  So I won't waste my time arguing with him.  Unfortunately
I haven't had a lot of time this weekend to explore the possibility
(just a hunch) that Salvadoraceae could be paraphyletic with respect to 
Bataceae.              
      Anyway, these families are certain very closely 
related (morphologically and molecularly), but as I said, that doesn't
mean that they are sister taxa.  My hunch in that regard is now
zeroing in on genus Azima in particular.  Batis and Azima seem to
share the possession of ovules which are secondarily partitioned by a
false septum 
(unlike Salvadora and Dobera).  A less convincing similarity is
chromosome number, 2n=22 in Batis and Azima, as opposed to Salvadora
with 2n=24. However, there may be exceptions to this (and not sure of 
chromosome number in Dobera).          
      However, the ovule morphology seems significant enough 
that I hope to find other characters which are shared by Azima and Batis 
(perhaps even molecular ones, although there seems to be few sequences
available at the present time).  Anyway, biogeographically I can see
Azima giving rise to Batis once it crossed the Wallace line, and a
transition from a miohalophyte to more extreme euhalophyte perhaps
making possible (at some point in time) a trans-Pacific dispersal from
New Guinea or Australia to the New World.   
        I would be interested to hear from any botanists 
who might know of other similarities between Batis and only Azima among
the Salvadoraceae. If so, perhaps it might be appropriate to bring
Family Azimaceae out of synonymy (back to full family status).   
                -------Ken Kinman   

                              
P.S.  In view of John's criticisms, it should be remembered that
dispersal ability certainly does not ensure that oceanic dispersals will 
be successful in most cases.  Being able to disperse long distances is

only the first step, but lack of suitable habitat, and more importantly
competitive exclusion by other taxa already well-established, are
obviously barriers to even good dispersers being automatically spread
geographically.  Such arguments against dispersalist hypotheses are
therefore unconvincing (perhaps simple, but perhaps too often 
simplistic).                  
---------------------------------------------             

  
I wrote: 
          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.         
______________________________________