Individual Differences in Foraging Strategies of Parasitic Sabre-Tooth Blennies

Andrea Bshary,Redouan Bshary,Cédric Sueur

doi:10.1371/journal.pone.0045998

Abstract

Originally, evolutionary game theory typically predicted that optimal behaviour in a given situation is uniform or bimodal. However, the growing evidence that animals behave more variably while individuals may differ consistently in their behaviour, has led to the development of models that predict a distribution of strategies. Here we support the importance of such models in a study on a coral reef fish host–parasite system. Parasitic blennies (Plagiotremus sp.) regularly attack other fishes to bite off scales and mucus. Individuals of some victim species react to being bitten with punishing the parasite through aggressive chasing. Our field observations and laboratory experiments show that individual blennies differ markedly in how they incorporate being punished into their foraging decisions. We discuss how these differences may affect the payoff structure and hence the net effect of punishment on punishers and on the appearance of a public good for look-alikes.

Highlights

Cooperation in groups that consist of more than two unrelated individuals has attracted considerable research interest
Field observations at Ras Mohammed National Park were conducted with permission from the Egyptian Environmental Affairs Agency (EEAA) in Cairo
In previous studies on parasitic blenny–victim interactions we had found evidence for a public good that is maintained through blenny–foraging decisions in two ways [13,15]

Summary

Introduction

Cooperation in groups that consist of more than two unrelated individuals has attracted considerable research interest. A key problem for achieving cooperation in larger groups is typically illustrated with the standard public goods game. In this game each group member may contribute to a communal purse. After each round the group’s gains are split between group members, irrespective of how much each individual contributed. These rules typically lead to a situation where it is in the group interest that everybody contributes while for individuals contributions are altruistic in the evolutionary sense [1], i.e. contributions reduce the actor’s direct benefits. It has been repeatedly demonstrated that humans fail to cooperate in this game [2,3], which fits the ‘tragedy of the commons’ idea developed by Hardin 1968

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