Chaoborus predation and delayed reproduction in Daphnia: a demographic modeling approach |
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Authors: | Howard P Riessen |
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Institution: | (1) Department of Biology, SUNY College at Buffalo, 1300 Elmwood Avenue, Buffalo, New York, 14222-1095, USA (fax |
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Abstract: | I develop a demographic model that examines the impact of Chaoborus predation on the population dynamics and life history of Daphnia. Predation effects are determined through analysis of the various components of the predator-prey interaction (encounter,
attack, strike efficiency), and are integrated into a stage-classified matrix population model. The model is parameterized
with data from interactions between D. pulex and fourth-instar C. americanus. I test this model with two laboratory experiments that examine population growth of D. pulex under the influence of five different levels of Chaoborus predation. With the exception of a single predation treatment in each experiment, the model accurately predicted the observed
reduction in Daphnia numbers with increasing Chaoborus predation. I then use this model to investigate the evolution of delayed reproduction in D. pulex that are exposed to Chaoborus. I ask whether delayed reproduction may evolve in Daphnia that are subjected to Chaoborus predation as a trade-off for the benefits of larger body size. The model predicts that the effectiveness of such a life history
trade-off depends on the relative sizes of predator and prey. In some interactions between Chaoborus and Daphnia, increasing Daphnia body length by as little as 5% from base growth trajectories sufficiently increases fitness (by reducing vulnerability to
Chaoborus predation) to compensate for the cost of delayed reproduction. In other interactions, however, increased body length provides
no benefit to Daphnia (and may even reduce fitness), and selection would act against the evolution of delayed reproduction.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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Keywords: | body size Chaoborus americanus Daphnia pulex delayed reproduction demographic model induced antipredator defenses life history size-selective predation trade-offs zooplankton |
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