Competition theory, evolution, and the concept of an ecological niche

Abstract

This article examines some of the main tenets of competition theory in light of the theory of evolution and the concept of an ecological niche. The principle of competitive exclusion and the related assumption that communities exist at competitive equilibrium - fundamental parts of many competition theories and models - may be violated if non-equilibrium conditions exist in natural communities or are incorporated into competition models. Furthermore, these two basic tenets of competition theory are not compatible with the theory of evolution. Variation in ecologically significant environmental factors and non-equilibrium in population numbers should occur in most natural communities, and such changes have important effects on community relations, niche overlap, and the evolution of ecosystems. Ecologists should view competition as a process occurring within a complex dynamic system, and should be wary of theoretical positions built upon simple laboratory experiments or simplistic mathematical models. In considering the relationship between niche overlap and competition, niche overlap should not be taken as a sufficient condition for competition; many factors may prevent or diminish competition between population with similar resource utilization patterns. The typically opposing forces of intraspecific and interspecific competition need to be simultaneously considered, for it is the balance between them that in large part determines niche boundaries.

Niche relations in Vicia‐inhabiting Bruchus spp

“…A further factor decreasing the probability of interspecific competition is the activity of parasitoids (Alley, 1982). The abundance of natural enemies also prevents full exploitation of the available resources (Faeth, 1990).…”

Predation by Macrolophus pygmaeus (Hemiptera: Miridae) on Acyrthosiphon pisum (Hemiptera: Aphididae): Influence of prey age/size and predator's intraspecific interactions

“…Diverse types of potential interactions may occur between two or more individuals of the same species when competing for food, space and/or oviposition sites (Klomp, 1964;Alley, 1982;Symondson et al, 2002;DeLong & Vasseur, 2011). When predators compete for prey, one often observes non-interactive as well as interactive individuals, which by mutual interference or synergic interactions (density dependent predation), infl uence in different ways prey population dynamics (Klomp, 1964;Alley, 1982;Losey & Denno, 1998;DeLong & Vasseur, 2011).…”

“…When predators compete for prey, one often observes non-interactive as well as interactive individuals, which by mutual interference or synergic interactions (density dependent predation), infl uence in different ways prey population dynamics (Klomp, 1964;Alley, 1982;Losey & Denno, 1998;DeLong & Vasseur, 2011). Until now, the effect of intraspecifi c competition between individuals of M. pygmaeus has only been recorded in two studies in which whitefl y was the prey (Lucas & Alomar, 2002;MorenoRipoll et al, 2012).…”

A theory of the competing supply chain: Alternatives for development

“…Over time, the niche theory of competition has become synonymous with competition theory (Colwell, 1999;Alley, 1982) which has largely come about as a result of its history with competition theory rather than logic. The development of the work known and called niche theory was started by Robert MacArthur and Richard Levins (1967).…”

“…It is on this notion of similarity that the niche theory of competition finds its basis for competition, by using such concepts as niche breadth and niche overlap. Based on the principle of competitive exclusion, a niche is defined as the extent of environmental variation, in both biotic and abiotic factors, under which a species can engage in activities necessary for its survival (Alley, 1982). In this sense, species are viewed to have a multidimensional relationship with the environment.…”