Nonlinear competitive variance

Nonlinear competitive variance is a species-coexistence mechanism which depends on species differences in nonlinear responses to variable competition. It can affect the outcome of competition when population growth rates are nonlinear functions of variable competition and species differ either in the nature of the nonlinearity (relative nonlinearity) or in the variance of the competition that they experience.

Reference

Snyder, R.E., Chesson, P. 2004. How the spatial scales of dispersal, competition, and environmental heterogeneity interact to affect coexistence The American Naturalist 164, 633–650.