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Emergence 2009: Semester Projects II


Biology 361 = Computer Science 361
Bryn Mawr College, Spring 2009


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Download/view: Evolve05.nlogo


This model is the fifth generation in my effort to create a basic model of evolution.

SETUP, STEP, and GO are standard.

ADD PREDATOR adds a single predator at a random location.

INIT-PREDATORS controls how many predators are included in SETUP.

PRED-RADIUS controls the radius in which predators can sense prey.

INIT-PREY controls how many prey are included in SETUP.

SPAWN-AGE controls how many ticks prey must survive for before reproducing.

SIGHT-DIST-SETUP controls the distribution of sight-dist values within the prey population upon SETUP. RANDOM sets each to a random value from 0 to 9, NORMAL sets them randomly based on a normal distribution SET TO SLIDER sets the value for all turtles to the value set by the INIT-SIGHT-DIST slider. The same is true for the SIGHT-ANGLE-SETUP chooser and the INIT-SIGHT-ANGLE slider.

Try starting out with no predators. Use different trait setup options and different slider settings for the SET TO SLIDER option. Watch how the mean and distribution of trait values varies. Next try adding a predator (or doing a SETUP with some INIT-PREDATORS)- how do predators affect the mean and distribution of trait values? Can you select settings that cause all the prey to go extinct?
Having incorporated a 'field of vision,' I am interested in seeing if I can manipulate the model to show differential selection for one trait or the other. I would also like to add some traits for the predators and see what kind of 'arms race' results.
I used separate breeds for predators and prey so that I could easily control them separately. I also had to do some careful thinking to get the graph working how I wanted- note the recursion, the use of 'bins', of the ROUND primitive, and of separate plot pens in the graph-trait procedure.


Models created using NetLogo.


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