Study
The Struggle for Existence
Gause, G. F.
Williams & Wilkins, 1934
Populations of Paramecium species were grown in controlled culture on a bacterial food supply, first in isolation to establish how each grows alone, then in mixed culture with a competitor. Population densities were counted over time under a constant renewal regime.
- Studied in
- Paramecium aurelia, Paramecium caudatum, Paramecium bursaria
- Sample size
- replicated laboratory cultures grown alone and in mixture
Grown alone, each species reached a stable density. Grown together on the same food supply, one species declined to extinction while the other persisted. Where two species used the culture differently — one feeding in suspension, the other on the vessel floor — both persisted at reduced densities.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
Two species making their living in exactly the same way cannot coexist indefinitely; the outcome depends on how they use the resource rather than on which is stronger in the abstract.
How NatureHQ reads it
The experiment that made competition testable rather than assumed. What it is repeatedly asked to prove — that two species can never share a resource — is not what it shows, and Gause’s own third case is the reason: when the two paramecia used the same tube differently, both survived in it. The exclusion result and the coexistence result came from the same set of experiments.
- Laboratory cultures with a constant environment, a single renewed resource and no refuge, predator or disturbance.
- A stable environment is exactly the condition under which exclusion is most likely; natural systems rarely provide it.
Two species, one tube of food
If two species make their living the same way, can they share a resource — or does one of them go?
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Published by: Academic book publishersPublished as an academic monograph.
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