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Predation cost of rapid growth: behavioural coupling and physiological decoupling

Authors

  • ROBBY STOKS,

    Corresponding author
    1. Laboratory of Aquatic Ecology, University of Leuven, Ch. de Bériotstraat 32, 3000 Leuven, Belgium;
      Robby Stoks, Laboratory of Aquatic Ecology, University of Leuven, Ch. de Bériotstraat 32, 3000 Leuven, Belgium. Tel: + 32 16 32 37 10; Fax: + 32 16 32 45 75; E-mail: robby.stoks@bio.kuleuven.be
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  • MARJAN DE BLOCK,

    1. Evolutionary Biology Group, University of Antwerpen, Groenenborgerlaan 171, 2020 Antwerpen, Belgium
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  • FRANK VAN DE MEUTTER,

    1. Laboratory of Aquatic Ecology, University of Leuven, Ch. de Bériotstraat 32, 3000 Leuven, Belgium;
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  • FRANK JOHANSSON

    1. Department of Ecology and Environmental studies, Umeå University, 90187 Umeå, Sweden
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Robby Stoks, Laboratory of Aquatic Ecology, University of Leuven, Ch. de Bériotstraat 32, 3000 Leuven, Belgium. Tel: + 32 16 32 37 10; Fax: + 32 16 32 45 75; E-mail: robby.stoks@bio.kuleuven.be

Summary

  • 1Despite its prominent role in life-history theory, there is no direct empirical evidence for a behaviourally mediated predation cost of rapid growth. Moreover, we know little about how digestive physiology may also influence the shape of the growth/predation risk trade-off function.
  • 2We determined the role of behaviour and digestive physiology in experiments in which damselfly larvae were induced to grow slowly or rapidly by manipulating photoperiod (time stress), and exposure to a fish predator.
  • 3We showed that larvae under time stress grew more rapidly. Rapid-growing larvae had a higher foraging activity and a higher growth efficiency.
  • 4Under predation risk, larvae not only had a lower foraging activity but also a lower growth efficiency.
  • 5Rapid-growing larvae (i.e. those under time stress) balanced the growth/predation risk trade-off differently and took more risk in the presence of a predator, which resulted in a behaviourally mediated higher predation cost compared to slow-growing larvae. Their higher growth efficiency, however, made this cost smaller compared to a completely behaviourally mediated rapid-growth strategy.
  • 6Our results provide the first explicit experimental proof of a behaviourally mediated predation cost of rapid growth. Besides a behavioural coupling of growth and predation risk, resulting in the well-known trade-off, we also found a partial decoupling of these two processes by digestive physiology.

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