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Scared fish get lazy, and lazy fish get fat
Article first published online: 12 MAR 2009
DOI: 10.1111/j.1365-2656.2009.01530.x
© 2009 The Authors. Journal compilation © 2009 British Ecological Society
Additional Information
How to Cite
Johansson, F. and Andersson, J. (2009), Scared fish get lazy, and lazy fish get fat. Journal of Animal Ecology, 78: 772–777. doi: 10.1111/j.1365-2656.2009.01530.x
Publication History
- Issue published online: 4 JUN 2009
- Article first published online: 12 MAR 2009
- Received 30 September 2008; accepted 19 January 2009Handling Editor: Stephen Hall
Keywords:
- adaptation;
- anti-predator behaviour;
- body shape;
- induced defence;
- phenotypic plasticity
Summary
- 1Many biological textbooks present predator-induced morphological changes in prey species as an example of an adaptive response, because the morphological change is associated with lower predation risk. Here we show that the adaptive morphological response observed in many systems may actually be an indirect effect of decreased activity – which reduces the predation risk – rather than a direct adaptive response.
- 2One of the classical examples comes from crucian carp, where the presence of pike leads to a deeper body. We manipulated pike cues (presence and absence) and water current (standing and running water) and found that both standing water and pike cues similarly and independently induced a deeper body.
- 3Since the presence of pike cues as well as standing water might be associated with low swimming activity, we suggest that the presence of pike causes a reduction in activity (antipredator behaviour). Reduced activity subsequently induces a deeper body, possibly because the energy saved is allocated to a higher growth rate.
- 4Our result suggests that even if morphological change is adaptive, it might be induced indirectly via activity. This important conceptual difference may be similar in many other systems.