What Is Gause’s Exclusion Principle?

Gause’s Exclusion Principle states that when two species compete for exactly the same resources under constant environmental conditions, one species will inevitably outcompete and exclude the other from the habitat. This occurs because even a slight advantage in resource use, growth rate, or survival will allow one species to dominate, leading to the decline or extinction of the less competitive species12356.

This principle is often summarized as: “Complete competitors cannot coexist.”

Experimental Basis

The principle is named after Russian ecologist Georgy Gause, who demonstrated it in classic laboratory experiments using two species of Paramecium (P. aurelia and P. caudatum). When grown together in a controlled environment with limited resources, one species consistently outcompeted the other, leading to the exclusion of the weaker competitor156.

Interspecific vs. Intraspecific Competition

• Intraspecific competition occurs within a single species, as individuals compete for resources like food, space, or mates.

• Interspecific competition occurs between different species competing for the same resources.

Gause’s Exclusion Principle specifically applies to interspecific competition—that is, competition between different species occupying the same ecological niche and using the same limited resources12345678.

Why Not Intraspecific Competition, Predation, or Niche Tolerance?

• Intraspecific competition does not lead to exclusion between species, but rather regulates population size within a species.

• Predation is a different type of interaction, involving one organism feeding on another, not direct competition for the same resource.

• Niche tolerance refers to the range of environmental conditions a species can tolerate, not direct competition.

Ecological Implications

Gause’s Exclusion Principle highlights the importance of niche differentiation and resource partitioning for species coexistence. When two species compete for the same resources, one must adapt to use different resources, occupy a different niche, or face exclusion from the community. This drives evolutionary divergence and promotes biodiversity by reducing direct competition1256.

Conclusion: The Correct Application

Gause’s Exclusion Principle applies to:

(2) Interspecific competition

Understanding this principle is crucial for ecologists and conservationists as it underpins the dynamics of species interactions, community assembly, and the maintenance of biodiversity in ecosystems.