Migration strategies

[Cris Guppy or Aud Fischer]

I agree with Phil Schappert's definition. I think uni-directional movement,
without a return trip, can be migration if it fits the definition. However,
in that case the interesting evolutionary question arises: If migration
occurs in only one direction, it is 100% fatal as far as the remaining
portion of the population that did not migrate is concerned. So why would
the trait of migration remain within the population?
 
----- Original Message -----
From: "rudy benavides" <rbenavid at hotmail.com>
To: <leps-l at lists.yale.edu>
Sent: Monday, January 15, 2001 4:40 AM
Subject: Re: Migration strategies
 
 
> Thanks for all your responses which were quite varied.  Especially
> concerning the use of migration and dispersal which was used so
differently
> by some of you (on and off-list). I am comfortable in using the definition
> used by Phil Schappert in his book *A World for Butterflies  Their Lives,
> Behavior and Future*.  In it he states that "migration is a directed,
> long-distance, seasonal movement of individuals, whereas dispersal does
not
> necessarily require long distances or need to be seasonal."  Some
responses
> seemed to imply that for migration to occur, there had to be a return trip
> (the re-colonization) associated with the journey--- requiring the journey
> be bi-directional to fit the definition.  Mis-interpretation on my part...
> or can migration occur in one direction only?  I didn't want to get into a
> big definition squabble, but..
>
> Rudy Benavides
> In the Maryland Piedmont
>
>
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