Summary
Two species competing for exactly the same niche cannot coexist indefinitely.
In depth
Gause's experiments (1930s) with two Paramecium species: grown separately each thrived, but together P. aurelia outcompeted P. caudatum. Coexistence requires differences in resource use.
Character displacement is the evolutionary result.
The principle requires complete niche overlap and stable conditions. Exclusion can be prevented by disturbances or predators.
Example: Connell's barnacle experiments showed Chthamalus excluded from the lower shore by Balanus.
Frequently asked questions
What is Competitive Exclusion?
Two species competing for exactly the same niche cannot coexist indefinitely.
Which area of biology covers Competitive Exclusion, and how advanced is it?
Competitive Exclusion is one of the 54 topics in Ecology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Competition, Habitat and Niche, Keystone Species.
Can you give an example of Competitive Exclusion?
Darwin's finch beaks differ more where species overlap.
What should I learn before Competitive Exclusion?
Work through the Beginner topics in Ecology first, such as Ecology, Ecosystem, Biotic and Abiotic Factors, then return to Competitive Exclusion. Intermediate topics assume the Beginner vocabulary.
What topics are related to Competitive Exclusion?
The closest topics to Competitive Exclusion are Competition, Habitat and Niche, Keystone Species, Exponential Growth. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Competitive Exclusion?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Competitive Exclusion. To practise the whole of Ecology, use the Ecology quiz.
How is Competitive Exclusion different from Competition?
Competitive Exclusion: Two species competing for exactly the same niche cannot coexist indefinitely. Competition: Interaction in which organisms vie for the same limited resource, intraspecific or interspecific. Read both side by side and note what each one explains.
How should I study Competitive Exclusion step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Competition and explain the difference aloud. Finally, take the Ecology quiz and come back to this page for any question you miss.