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

[Kenneth Kinman]

John, 
      Theoretically, a single character may be all that
there is in an extremely densely packed series of fast evolving of
clades.  However, in the vast majority of cases, there should be
multiple synapomorphies, simply because the fossil record is so poor and

thus eliminating the intermediates (which very often wouldn't show the
needed information even if there were more intermediate fossils).                        
  
      In this case, we have a double whammy of an extremely
poor fossil record and not sufficient research done on extant taxa
(especially on Azima and Dobera).  Morphology (of the flowers, etc.) has

raised more questions than answers, so the answer most likely lies in
characters that are biochemical or better yet a lot more molecular
sequences.     
  
        Nevertheless, there does seem to be a general
trend of Salvadoraceae in the western part of Eurasia living in drier,
terrestrial habitats (although often in soils that are somewhat high in
salinity). But in eastern Asia, we see a greater ability to live in
wetter and even more saline habitats near the coasts.  Genus Azima seems

the most adapted of Salvadoraceae to such wetter saline environments,
with the ability to disperse to oceanic islands (such as islands in the
Indian Ocean). 

      I can see this as a precursor (pre-adaptation if you wlll) for
Azima jumping the Wallace Line and giving rise to genus Batis in New
Guinea and Australia.  Azima has seeds (and even their whole bodies)
that had become pre-adapted to dispersals (even across the entire
Pacific Ocean, although perhaps only once under just the right
conditions).  That their ancestors colonized islands in the Indian Ocean

could have been just one step in their subsequent invasion of
Australasia and then even the coasts of the tropics of the New World.
                       
               -----------Ken        
                          
P.S. This might seem a bit ironic, since the ancestors of the
Salvadoraceae-Bataceae clade no doubt came from eastern North America in

the first place and then migrated to Africa and/or Europe.   However,
it is perhaps not surprising that it could have taken a trip around the
globe to acquire adaptations to more extreme environments in order to
eventually reinvade North America and compete with relatives they left
behind many millions of year earlier.  But I guess such a scenario must
be disconcerting to someone who finds it hard to accept dispersal as
being that important, especially potentially so serially extensive
biogeographicaly.
---------------------------------------------              
John Grehan wrote: 
           I am not aware that there is anything
preordained about the number of synapomorphies being required for any
one clade. One is sufficient. Of course it would only take one other
character relationship to make that problematic so it may be regarded as

a 'weak' clade, but then again one character may be all that there is.