Figure 2.
Mutualist population size in the sink patch of the two-patch model. The invasion and maintenance of mutualists in the sink is favored by increasing host productivity in the source patch (r1), the migration rate (ε1), and decreasing the strength of density-dependent regulation of the host population (q). Simulations were initiated with no mutualists in the sink patch. Population size was measured as the mean of the last 200 generations of a simulation running for 2000 generations. Parameters: b = 1, (δE = δM) = 0.1, r = 1, γ = 0.1, u = 1. Although not shown here, low values of u resulted in more mutualists persisting in the sink patch.