Figure 1. Conceptual diagram to explain the different predictions of the Red Queen and stationary models of community evolution. In the Red Queen model, evolution is driven by biotic interactions and occurs at a stochastically constant rate (diagonal line). In the stationary model, evolution and extinction only occur during times of environmental change (darker regions). At these times, the predicted pattern is similar to the Red Queen model. However, evolution ceases in the stationary model during times of environmental stability (unshaded regions). Long periods of environmental stability (e.g. Period 6) may produce ‘Lost Worlds’ consisting of ancient and long-lived species.