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BRIDGES

                                             July 8, 2011

Tim Flannery's book "The Eternal Frontier".

A vision of North America throughout the eons:

  o  A "climate trumpet" of vertical mountain ranges,
     with extreme seasons and an exaggerated response
     to changes.

  o  Periodically connected and invaded by species from larger
     land masses, and then disconnected to evolve on it's own.

Flannery presents some general principles which
I gather are not controversial: typically the
species from larger landmasses defeat the smaller.

  Presumably, the larger arena presents a tougher
  challenge, and stronger evolutionary pressures.

     Robustness is proportional to pool size.


                                         Successful invading species are
                                         (1) adapted to hard environments
                                         (2) have a degree of altruism
                                             ("helpers at the nest")


There's also a pattern of older forms
surviving on the periphery, where after
a change in conditions, the old forms
may spread once again, and may become
dominant once more.

     So: the periphery acts
     as a library, a storage place.
                                                     CONNECTIVITY

                                                         CONTROL

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