title: Competitive exclusion and limiting similarity: a unified theory.
abstract: Robustness of coexistence against changes of parameters is investigated in a model-independent manner by analyzing the feedback loop of population regulation. We define coexistence as a fixed point of the community dynamics with no population having zero size. It is demonstrated that the parameter range allowing coexistence shrinks and disappears when the Jacobian of the dynamics decreases to zero. A general notion of regulating factors/variables is introduced. For each population, its impact and sensitivity niches are defined as the differential impact on, and the differential sensitivity towards, the regulating variables, respectively. Either the similarity of the impact niches or the similarity of the sensitivity niches results in a small Jacobian and in a reduced likelihood of coexistence. For the case of a resource continuum, this result reduces to the usual "limited niche overlap" picture for both kinds of niche. As an extension of these ideas to the coexistence of infinitely many species, we demonstrate that Roughgarden's example for coexistence of a continuum of populations is structurally unstable.
authors.affiliation: Department of Biological Physics, Eötvös University, Pázmány Péter sétány 1A, H-1117 Budapest, Hungary. geza.meszena@elte.hu
authors.forename: Géza
authors.initials: G
authors.lastname: Meszéna
authors.forename: Mats
authors.initials: M
authors.lastname: Gyllenberg
authors.forename: Liz
authors.initials: L
authors.lastname: Pásztor
authors.forename: Johan A J
authors.initials: JA
authors.lastname: Metz
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D003163:Competitive Behavior; D008954:Models, Biological; D011157:Population Dynamics