Load P2b, then press [E] and load the two Paramecium
- Examine the isocline configuration (see figure)
noting that a community equilibrium occurs at high P. aurelia
density and low P. caudatum density.
- Plot the data with [F3] and notice how they approach
then oscillate around the community equilibrium (see figure).
- Press [F8] and run a deterministic simulation, noting
how the simulated trajectory curves in to the community equilibrium
point (see figure).
- Examine the correspondence between the simulated deterministic
trajectories and the data on arithmetic
and logarithmic time series plots.
- Run several stochastic simulations and compare the simulated
trajectories to the original data (see figure).
In this experiment, the two species of Paramecium were
able to coexist near a stable community equilibrium. However,
competition between the two species was asymmetrical, with P.
aurelia obtaining a higher equilibrium density due to its
greater maximum per-capita rate of increase (A1 = 0.89
versus A2 = 0.73) rather than its competitive ability (C12
= -0.0025 versus C21 = -0.0015). In other words P.
aurelia had a growth rate advantage and P. caudatum
a competitive advantage, and this enabled them to coexist.