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Coexistence in Laboratory Populations of Paramecium Aurelia and Its Predator Didinium Nasutum
Leo S. Luckinbill
Vol. 54, No. 6 (Nov., 1973), pp. 1320-1327
Published by: Wiley
Stable URL: http://www.jstor.org/stable/1934194
Page Count: 8
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Previous attempts at the prolonged laboratory study of predator-prey systems lacking refuges or physical complexity have been unsuccessful. The addition of Methyl Cellulose to interacting laboratory populations of Paramecium aurelia and its predator, Didinium nasutum, prolongs coexistence by reducing the frequency of contact between predator and prey. The study of this system under controlled conditions revealed the perturbing influence of a time delay in the predator population that resulted in oscillations of increasing amplitude terminating with D. nasutum's extinction. Enrichment of the system by supplying excess bacteria resulted in the extinction of P. aurelia. The perturbing effect of D. nasutum's time delay was counteracted by reducing the amount of bacterial food for Paramecium. In this system, prey became food-limited at their peak density, resulting in limit cycle oscillations of predator and prey at approximately constant amplitude. The medium used for these experiments lack physical inconsistencies that might act as barriers to movement and did not provide the prey with a superior dispersal ability. Coexistence of the predator and prey in this experimental system did not result from the introduction of refuges or physical complexity.
Ecology © 1973 Wiley