Fig. 1.

Types of regime shifts, based on Beisner et al. (3). The ball represents an ecological system, and the basins represent equilibria: If a ball is dropped, it will settle in a basin. (A) Regime shift due to a “shift in variables.” Here, a force that is external to the dynamic system (e.g., an exogenous shock or perturbation) pushes the system across a fixed threshold and into a new basin. (B) Regime shift due to a “shift in parameters.” Here, a change in a parameter of the dynamic system (e.g., carrying capacity, death rate) alters the topology of the system (i.e., the “shape” of the dynamic system, defining thresholds and basins of attraction) so that the system moves into the new basin.