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Large-amplitude cycles of Daphnia and its algal prey in enriched environments

McCauley, E. and Nisbet, R.M. and Murdoch, W.W. and de Roos, A.M. and Gurney, William (1999) Large-amplitude cycles of Daphnia and its algal prey in enriched environments. Nature, 402 (9). pp. 653-657. ISSN 0028-0836

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Abstract

Ecological theory predicts that stable populations should yield to large-amplitude cycles in richer environments1±3. This does not occur in nature. The zooplankton Daphnia and its algal prey in lakes throughout the world illustrate the problem4±6. Experiments show that this system its the theory's assumptions7±9, yet it is not destabilized by enrichment 6. We have tested and rejected four of ive proposed explanations 10. Here, we investigate the fifth mechanism: inedible algae in nutrient-rich lakes suppress cycles by reducing nutrients available to edible algae. We found three novel results in nutrient-rich microcosms from which inedible algae were excluded. First, as predicted by theory, some Daphniaedible algal systems now display large-amplitude predator-prey cycles. Second, in the same environment, other populations are stable, showing only small-amplitude demographic cycles. Stability is induced when Daphnia diverts energy from the immediate production of young. Third, the system exhibits coexisting attractors -a stable equilibrium and large-amplitude cycle. We describe a mechanism that flips the system between these two states.

Item type: Article
ID code: 41791
Keywords: daphnia, algal prey , large-amplitude cycles , Probabilities. Mathematical statistics, Biology, General
Subjects: Science > Mathematics > Probabilities. Mathematical statistics
Science > Natural history > Biology
Department: Faculty of Science > Mathematics and Statistics
Related URLs:
    Depositing user: Pure Administrator
    Date Deposited: 29 Oct 2012 12:59
    Last modified: 05 Sep 2014 18:38
    URI: http://strathprints.strath.ac.uk/id/eprint/41791

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