[Taxacom] Just one species of Bromeliales in Africa

[Kenneth Kinman]

Dear All,   
       Bromeliads (Order Bromeliales) are largely a taxon of the New
World, except for the species Pitcairnia feliciana.  It has been
suggested that this species was dispersed (by its seeds) to Africa by
migrating birds millions of years ago (but is that the only
possibility?).                  
      This species is apparently only found on cliffs and rocks near the
coast, so dispersal by migrating birds nesting in those areas seems to
make sense.  However, I wonder why this species failed to spread (either
by birds or wind) inland to other areas of Africa.  

      Is this a case of a dispersed species by sheer luck just barely
establishing itself in marginal habitats on a new continent, but
apparently could not compete with well-established commelinoids beyond
this restricted area?  If so, what was it about this species that
prevented it from spreading into other areas of Africa?  On the face of
it, it seems odd that it could disperse a great distance across an
ocean, but was unable to disperse much shorter distances inland.  Was it
competition or lack of suitable habitat?   
             ----------Ken Kinman