Evol Ecol Res 9: 789-800 (2007)     Full PDF if your library subscribes.

Protozoan functional responses: effects of species, genotype, and anti-predator defences

Shelly Duquette, Res Altwegg‡ and Bradley R. Anholt*

Department of Biology, University of Victoria, PO Box 3020 Stn CSC, Victoria, BC V8W 3N5, Canada

Author to whom all correspondence should be addressed.
e-mail: banholt@uvic.ca


Hypothesis: Induced anti-predator defences reduce foraging efficiency.

Organism: Two clones of Euplotes aediculatus, and one clone of E. plumipes, species of hypotrich ciliated protozoan feeding on the green alga Chlorella vulgaris.

Study site: Laboratory experiment.

Methods: We induced defences using frozen turbellarian flatworm predators. We counted captured cells directly using the autofluorescence of chlorophyll. We then estimated functional responses of induced and uninduced morphs using non-linear mixed effects models of counts of captured cells.

Results: All clones had Type II functional responses. Variation in attack rates and handling times was as large between clones as between species. Only the clone with the largest morphological change clearly had reduced foraging efficiency. This was due to longer handling times.

Keywords: Chorella, chlorophyll autofluorescence, Euplotes, model selection, phenotypic plasticity, Stenostomum.

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