Figure WN28.2. Stable coexistence of prey with predators. (A) Effect of prey numbers on predator fitness is a = +5; of predator numbers on prey fitness is b = 0.5; and rate of decline of prey in the absence of predators is ρ = 3. (Short dashed line) Boundary between regions where prey density increases (below, yellow tint) and decreases (above). (Long dashed line) Boundary between regions where predators increase (right, red tint) and decrease (left). The curves show the trajectories followed by populations as they converge on the stable equilibrium (purple). There are also unstable equilibria (red) where both species are extinct (bottom left) or where just predators are extinct (bottom right). (B) Fluctuations of predator and prey abundance as predators invade prey and prey decline. These correspond to the trajectory in A that connects the unstable equilibrium at bottom right to the stable interior equilibrium.

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