Biodiversity in Spatial Rock-Paper-Scissors Games
The struggle for survival between competing bacteria species in a petri dish can create beautiful spiral patterns until one type conquers all the available space, destroying the entangled structure. Kerr and colleagues made this observation when they mixed three E. coli populations exhibiting cyclic dominance: A beats B beats C beats A. As derived by Tobias Reichenbach, Mauro Mobilia, and Erwin Frey, the mobility of the bacteria, that is, their spatial relocation rate, is crucial for the stability of coexistence. An applet recently published on The Wolfram Demonstrations Project allows anyone to simulate a spatial rock-paper-scissors game and observe the role mobility plays, whereas another applet shows the evolution of such populations if spatial effects are ignored.