## Competition Between
*Paramecia* Tutorial

Load **P2b**, then press [**E**] and load the two *Paramecium*
models.

- 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).

#### Conclusions

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 (*A*1 = 0.89
versus *A*2 = 0.73) rather than its competitive ability (*C*12
= -0.0025 versus *C*21 = -0.0015). In other words *P.
aurelia* had a growth rate advantage and *P*. *caudatum*
a competitive advantage, and this enabled them to coexist.

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