Conservation and evolution labs

Wed May 17 10:01:38 CDT 2000

There's a fun "game" illustrating evolution.  Students are predators, armed
with a paper cup and either a knife, fork, spoon, forceps, or fingers.  Prey
are beans painted various colors (red, green, brown, and white are what we
usually used, but sometimes we changed to two kinds of unpainted beans,
rice, and dried peas).  A pre-determined number of each prey type is
scattered in the lawn, on open ground, or even in the lab (that's when you
need to use rice as one prey type and forceps as one predator type) and
students forage for a certain length of time.

Then it's the breeding season.  Students gather, based on feeding mechanism,
and tally their prey.  Prey reproduction is based on number of individuals
that *didn't* get eaten, so the cryptic prey types increase in relative
abundance.  Predator reproduction is based on number of prey that *did* get
eaten by that feeding mechanism.

Those students who were unsuccessful predators trade their feeder for one of
the successful types.  Thus, successful feeding mechanisms proliferate among
the predators.

Prey offspring are scattered and another generation of foraging happens.

Knives die out the first generation.  Spoons do well at first, but after
about 4 generations, fingers generally have driven the other types extinct.
Sometimes forceps linger in low numbers by attacking fingers.  Red and white
beans usually go extinct quickly.  Green and brown success depends on how
lush the vegetation is on the playing field.  If played indoors, spoons do
much more poorly (harder to scoop the bean on a slick floor) and forceps do
quite well (even without piracy) if there's rice.  Rice outlives any color

All in all, it's fun and instructive.  The bother is in doing calculations
to determine the composition of the next generation.


Robin K Panza                         panzar at
Collection Manager, Section of Birds          ph:  412-622-3255
Carnegie Museum of Natural History       fax: 412-622-8837
4400 Forbes Ave.
Pittsburgh  PA  15213-4008  USA

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