Population regulation and the ecological niche

Abstract On the basis of the theory of robust coexistence the ecological niche—one of the most controversial concepts in ecology—can be appropriately defined and operationalized. Abstract definitions for the notions of niche space, regulating variable, niche, niche overlap, and niche segregation are given in this chapter, with the range of their interpretation extended to alleles and clones besides the usual ecological (species-oriented) one. Models formulated in discrete and continuous niche spaces and temporal niches with circular (seasonal) timescales are explained. Several empirical examples of the three types of niche segregation (-trophical, spatial, and temporal) are introduced. Relation of temporal niche segregation and the storage effect is discussed. The community context dependence of the niche space and of the niche of any specific variant is emphasized and explicated. An evolutionary toy model of competition-induced diversification—the central idea of Darwin—closes the chapter.