the mystery of Vanessa unidirectional migration

Liz Day beebuzz at kiva.net
Mon Apr 30 21:57:24 EDT 2001


I don't understand what advantage this bug gains by migating north every 
spring, if the adults don't then migrate back south in the fall, and (?) 
thus their offspring are instead killed off by winter.  Isn't this genetic 
suicide?   I understand dispersion is good, but it seems like consistent 
directional dispersion in a direction that is ultimately death would be 
selected against, eventually.   What is going on?  I must not be seeing the 
whole picture.

Thanks,

-------------------------------------------------------------
Liz Day
Indianapolis, Indiana, central USA  (40 N, ~86 W)
USDA zone 5b.  Winters ~20F, summers ~85F.  Formerly temperate deciduous 
forest.
daylight at kiva.net
www.kiva.net/~daylight
-------------------------------------------------------------
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buy something and dump it on or squirt it on, he will almost certainly do
it, after a fashion. But if you suggest that he observe something or think
about something or learn about something, he almost certainly will
not. Yet those gardens we admire are never the results of dumping and
squirting: they are always the result of muddling things about in the brain
and the eye."
-- from _The Essential Earthman_, by the late Henry Mitchell



 
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