Evol Ecol Res 7: 23-35 (2005) Full PDF if your library subscribes.
Balancing the thermal costs and benefits of refuge use to cope with persistent attacks from predators: a model and an experiment with an alpine lizard
Vicente Polo, Pilar López and José Martín*
Departamento de Ecología Evolutiva, Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal 2, 28006 Madrid, Spain
Author to whom all correspondence should be addressed.
When prey take refuge to reduce predation risk, they forfeit time for other activities. They may also pay a physiological cost. In particular, optimal regulation of body temperature is essential for ectotherms. Qualitative models predict that lizards have to balance anti-predatory decisions in relation to thermal conditions of the refuge and predation risk when deciding when to resume activity. However, these models are not general and empirical tests of their assumptions are scarce. We modified previous models to include the case of a high and maintained level of predation risk. The predictions of the model were further investigated in a laboratory experiment using male Iberian rock lizards. The same level of predation risk was displayed in two treatments in which temperature inside the refuge was high or low, and in the mating or the post-reproductive season. As predicted, lizards increased successive emergence times – an increase that was not linear but accelerating – and they had shorter emergence times when thermal costs of refuge use were higher. Nevertheless, body size of lizards and the season of the experiment had no effect on these decision rules. Our results are in line with an economical balance between costs and benefits in the decision rules controlling active versus inactive periods.
Keywords: costs of refuge use, Lacerta monticola, lizards, predation risk.
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