module is a simple simulation of the predator-prey dynamics based on "Sharks and fish wage an ecological war on the toroidal planet Wa-Tor"
(A.K. Dewdney, 1984). This prototype simulates the distribution
and abundance of the predator and prey through time as they interact
with each other in a hypothetical 2D space.
are the prey of the shark. They randomly move around in the
hypothetical toroidal world.
Agents (SA): These
are the sharks that preys on the FAs. They also move randomly
around the same hypothetical toroidal world and preys on FAs as they
– by chance – occupy the same space in
this prototype, both FA and SA have their own level of mortality. This
mortality is implemented as a proportion of the FA or SA that dies at
each time step.
FA are assumed to have an infinite supply of food. They have the capability of reproducing another one of
their kind upon reaching a user-defined reproductive age.
However, reproduction is on condition that space is available.
FA, SA have to passively "hunt" for prey to survive. A
starvation index is implemented that increases for each time step that
SA are not able to prey. The inverse is also true. SA will die if they reach a
threshold level identified by the value of the starvation index. Their reproduction is similar to FA.
addition to reproducing only when they have reached their own
reproductive age, they can only do so if their starvation index is
less than a set value.
GUI and Results:
graphical Torus 2D space presents the locations of the FA and SA. FA
are displayed as green circles and the SA are red circles (Fig. 1).
Fig. 1. Spatial distribution of agents (sharks are in red and fish
preys in green dots; plot for every 10 ticks).
Another chart presents the population of both populations (Fig.
2) and another, presents the age distribution of the preys.
Fig. 2. 2D plot of the fish and shark population in time (plot for
every 10 ticks).
here to download the classes and to run it with
RePast and simulate using
here to view the Java documentation of the classes; or
here to download the compressed API document.