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Bshary, Redouan

Nom
Bshary, Redouan
Affiliation principale
Fonction
Professeur ordinaire
Email
redouan.bshary@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/343
_
0000-0001-7198-8472

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  • Publication
    Accès libre
    Mutualism, market effects and partner control
    (2008)
    Johnstone, Rufus A.
    ;
    Bshary, Redouan 
    Intraspecific cooperation and interspecific mutualism often feature a marked asymmetry in the scope for exploitation. Cooperation may nevertheless persist despite one-sided opportunities for cheating, provided that the partner vulnerable to exploitation has sufficient control over the duration of interaction. The effectiveness of the threat of terminating an encounter, however, depends upon the ease with which both the potential victim and the potential exploiter can find replacement partners. Here, we extend a simple, game-theoretical model of this form of partner control to incorporate variation in the relative abundance of potential victims and exploiters, which leads to variation in the time required for individuals of each type to find a new partner. We show that such market effects have a dramatic influence on the stable level of exploitation (and consequent duration of interaction). As the relative abundance of victims decreases, they become less tolerant to exploitation, terminating encounters earlier (for a given level of exploitation), whereas exploiters behave in a more cooperative manner. As a result, the stable duration of interaction actually increases, despite the decreasing tolerance of the victims. Below a critical level of relative victim abundance, the model suggests that the cost of finding a replacement partner becomes so great that it does not pay to exploit at all.
  • Publication
    Accès libre
    Punishment and partner switching cause cooperative behaviour in a cleaning mutualism
    (2005)
    Bshary, Redouan 
    ;
    Grutter, Alexandra S.
    What are the mechanisms that prevent partners from cheating in potentially cooperative interactions between unrelated individuals? The cleaner fish Labroides dimidiatus and client reef fish both benefit from an interaction as long as the cleaner eats ectoparasites. However, the cleaner fish prefers some client mucus, which constitutes cheating. Field observations suggested that clients control such cheating by using punishment (chasing the cleaner) or by switching partners (fleeing from the cleaner). Here, we tested experimentally whether such client behaviours result in cooperative cleaner fish. Cleaners were allowed to feed from Plexiglas plates containing prawn items and fish flake items. A lever attached to the plates allowed us to mimic the behaviours of clients. As cleaners showed a strong preference for prawn over flakes, we taught them that eating their preferred food would cause the plate to either chase them or to flee, while feeding on flakes had no negative consequences. We found a significant shift in cleaner fish foraging behaviour towards flake feeding after six learning trials. As punishment and terminating an interaction resulted in the cleaners feeding against their preferences in our experiment, we propose that the same behaviours in clients improve the service quality of cleaners under natural conditions.
  • Publication
    Métadonnées seulement
    From parasitism to mutualism: partner control in asymmetric interactions
    (2002)
    Johnstone, Rufus
    ;
    Bshary, Redouan 
    Intraspecific cooperation and interspecific mutualism often feature a marked asymmetry in the scope for exploitation. Cooperation may nevertheless persist despite one-sided opportunities for cheating, provided that the partner vulnerable to exploitation has sufficient control over the duration of interaction. Here we develop a simple, game theoretical model of this form of partner control. We show that as a victim's ability to terminate an encounter increases, selection can favour reduced exploitation, resulting in a switch from parasitism to mutualism. For a given level of control, exploitation is likely to be less intense and the interaction to last longer when there are greater mutualistic benefits to be gained, and when the benefits of cheating are lower relative to the costs inflicted on the victim. Observations of interactions between cleaner-fish and non-predatory species of client are shown to match these predictions.