Variation-Dependent Mechanisms

Variation-dependent mechanisms are those that require variation in space in either population densities or environmental factors for their operation.  In the study of species coexistence, the storage effect and nonlinear competitive variance , in their spatial manifestations, are variation-dependent mechanisms of species coexistence. Fitness-density covariance is also a variation-dependent mechanism. Naturally, variation-dependent mechanisms are to be contrasted with variation-independent mechanisms.  This distinction was first presented in Chesson (2000a).  The related concepts to do with temporal variation are termed fluctuation-dependent, and fluctuation-independent mechanisms, as discussed in Chesson (2000b). 


Chesson, P. 2000a. General theory of competitive coexistence in spatially varying environments. Theoretical Population Biology 58, 211-237.

Chesson, P. 2000b. Mechanisms of maintenance of species diversity. Annual Review of Ecology and Systematics 31, 343-66.