[Taxacom] We're on a road to nowhere

[Kenneth Kinman]

Hi Jim,
      I agree completely.  The "why not" questions are often more
interesting (and more worthwhile pursuing).  The "why not" in Madagascar
questions are largely answered by failure to disperse at all, or in more
interesting cases, failure of dispersers to become established (at least
in cases occuring after the Jurassic, which are those I am most
interested in).  Failure to establish is due to lack of suitable habitat
(or competitive exclusion if that niche is filled), predation, or even
inbreeding.                
      Vicariance, on the other hand, would have played a greater role in
taxa of Jurassic age or older, but very little after the Jurassic.
That's been my main point, and the observation that panbiogeographers
generally seem to be overly willing to accept a vicariance hypothesis
and overly critical of dispersal hypotheses which make more sense (like
the Nile crocodile to New World dispersal).  And of course, it was the
Nile crocodile paper (and reaction to it) which started these threads.
That pretty much sums it all up for me, so I think I shall return to my
gardening---those weed seeds always trying to disperse their unwelcome
progeny into my garden.  :-(       
           -----------Ken                             
--------------------------------------------------------
Jim Croft wrote: 
     Well, it works when you are looking at spore bearing species.
Stand under a Cyathea with ripe sporangia and you really have to ask
yourself, just why aren't these damn things everywhere?  I guess the
same could be asked of marine species with a planktonic larval stage. 
Often the why not question is more more interesting than the why
question... :) 
jim 

On Sun, May 29, 2011 at 8:20 PM, Rob Smissen 
<SmissenR at landcareresearch.co.nz> wrote: 
> "Everything is everywhere" is the dispersalists null >hypothesis. Not
good for biogeography.