Redouan Bshary

Professor in behavioural ecology,
at the University of Neuchâtel

Biological markets in cleaning mutualism revisited

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Biological markets in cleaning mutualism revisitedBiological market theory has been extremely successful in predicting various aspects of mutualistic interactions, in particular payoff distributions as a function of supply and demand. Marine cleaning mutualism involving the cleaner wrasse Labroides dimidiatus and its ‘client’ reef fishes has been a prime example for the application of market theory. Clients visit cleaners to have ectoparasites removed but cleaners prefer to eat client mucus, leading to a conflict of interest. ‘visitor’ species, i.e. species with access to several cleaning stations, use partner choice/switching as a partner control mechanism to make cleaners feed against their preference and hence give a good service. Furthermore, cleaners give visitors priority over resident client species that have access to the local cleaner only. Nevertheless, several recent experiments of our group show that we have to develop biological market theory further in order to explain additional results. I will focus on two factors that may play a role in other markets as well. First, it is important to clarify how market forces interact with other important features of a system, like the degree of the temptation to cheat and alternative partner control mechanisms like punishment. Second, a key feature of human markets – the possibility to accumulate money – does not apply to biological markets. Instead, obtaining food in return for services like protection or transport is best described with a function of diminishing returns. Such functions may have interesting effects on market dynamics.

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