Spatial Population Ecological and Epidemiological Dynamics Simulator (SPEED Sim) is a tool that enables hands-on interactive exploration of the spatial dynamics of various computational models in population ecology and epidemiology. The app also provides several cellular automaton models as an introduction to these kinds of simulations. It currently includes thirteen different models:
- Conway's Game of Life: a classic cellular automaton that was created by mathematician John Conway in 1970.
- Vants: (Virtual Ants) demonstrates how extremely complex behaviour can arise from a set of very simple rules.
- Majority with long-distance interactions: models peer pressure, genetic drift or the spread of opinions and ideas.
- Diffusion-Limited Aggregation: models a process similar to crystallization, with diffusing particles aggregating out of solution.
- Cyclic Cellular Automaton: a generalized version of 'rock-paper-scissors.'
- SIRS epidemiological model
(Susceptible-Infectious-Recovered-Susceptible): demonstrates an infectious disease spreading through a population, where individuals have temporary immunity after recovering from the infection.
- Dispersal2 population model: a population model where individuals disperse their offspring at two local scales.
- Fragmented Landscape:a population model with local and long-distance dispersal on a spatially structured heterogeneous landscape.
- Competitive Species: an extension of the Fragmented Landscape model above, but with two species competing for available habitat with different strategies.
- Block Extinction: a spatial population ecology model where births occur individually, but when death occurs, entire blocks of sites go extinct simultaneously.
- Dynamic Landscape: a population model where some attempt is being made to control the population, for example with pesticides.
- Dynamic Landscape with Dormancy: an extension of the Dynamic Landscape model above, but now offspring has the potential to be 'dormant' and able to survive (but not reproduce) on unsuitable habitat.
- Vaccinated Communities epidemiological model: shows how the dynamics of an infectious disease are affected not only by the total amount of vaccination in a population, but also by the variability in vaccination levels among different communities.
The simulation models allow you to change all parameters controlling the dynamics. Images of the detailed spatial dynamics can be displayed, as well as graphs summarizing the behavior over time. Some of the models also allow the user to interactively draw new patterns in the system. Try a 'press-and-hold' and then moving your finger around on the lattice to draw. You can also pinch-to-zoom the lattice and the plots, and pan around them while zoomed.
Note that the simulations are generally computational intensive and will run more quickly on newer devices or when you select a smaller lattice size. The fast/slow slider next to the lattice image lets you slow down the simulation to observe the dynamics more closely.
This material is based upon work supported by the National Science Foundation under Grant Nos. DMS-0718786 and DMS-0746603 to David Hiebeler.