[Taxacom] Dispersal paradigm (was: Antarctic dispersal)

[Ken Kinman]

Hi Michael,                                                           I suppose the centre of origin/dispersal view has been dominant for thousands of years because humans have been able to recognize that their own species is so prone to such dispersal.  And today biologists can see the evidence that our species (and related species like Homo erectus) dispersed from smaller areas to occupy much larger areas (eventually including the Americas for Homo sapiens).  How widely we should extrapolate that to other taxa is obviously debatable, but I still believe that the most vocal proponents of vicariance (since the acceptance of continental drift) have often overdone their backlash against the predominant dispersal paradigm.     
      It really does far more harm than good to swing any pendulum too far, and more recently we have the resulting opposing backlash of dispersalists against too much vicariance.  Of course, this is not as extreme as the pendulum swing which resulted in a total rejection of all paraphyletic taxa (and throwing all the babies out with the bathwater), but it is still problematic.  In both cases, I believe a middle ground will be found that results in more balanced approaches.  In my view that means pulling back a bit on the vicariance front that went too far (and easing up on attacks against dispersalists), as well as accepting formal paraphyletic taxa where they are most useful (thus ending a decades-long backlash against all paraphyletic taxa whether they were good or bad).   In any case, I disagree with your panbiogeographic approach to both ratites and Order Crossosomatales, so I guess it is best to just agree to disagree on how much dispersal occurred during their evolution.  I also disagree that the age of the eudicot clade is nearly as problematic as you make it out to be.   So it goes.                                             ---------------------------Ken

Michael wrote:
Whether or not ideas are accepted or popular is interesting for sociology, but is not relevant to logical, scientific argument. The centre of origin/dispersal view is the dominant paradigm, and has been for thousands of years, but that does not mean it's right. In any case, the eudicot age is problematic (there is a whole section on it in my 2014 book (p. 67). 
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