Marine cleaning mutualisms provide new insights in biological market dynamics

Abstract

Most mutually beneficial social interactions (cooperation within species, mutualism between species) involve some degree of partner choice. In an analogy to economic theory as applied to human trading practices, biological market theory (BMT) focusses on how partner choice affects payoff distributions among non-human traders. BMT has inspired a great diversity of research, including research on the mutualism between cleaner fish Labroides dimidiatus and other marine fish, their ‘clients’. In this mutualism, clients have ectoparasites removed and cleaners obtain food in return. We use the available data on L. dimidiatus cleaner–client interactions to identify avenues for future expansion of BMT. We focus on three main topics, namely how partner quality interacts with supply-to-demand ratios to affect service quality, the role of threats and forms of forceful intervention, and the potential role of cognition. We consider it essential to identify the specifics of each biological market as a basis for the development of more sophisticated BMT models.

The interplay between satiation and temptation drives cleaner fish Labroides dimidiatus foraging behaviour and service quality towards client reef fish

“…Non-predatory clients can reduce the likelihood that cleaner fish eat their mucus by either punishing a cheating cleaner by chasing them, or by swimming off and seeking a different cleaner fish for their next cleaning interaction (Bshary & Grutter 2005). The ratio of parasite-to-mucus consumption by cleaner fish is thus a key variable describing their service quality (Bshary & Noë 2023). As mucus consumption often causes the occurrence of client 'jolts' (i.e.…”

“…The potentially unique feature of the Labroides cleaning mutualism is the conflict between protector and food provider over what the protector should eat. This conflict of interest may affect service quality in opposite ways than expected by the market law(Bshary & Noë 2023). The effects of other ecological settings on protection quality have not been studied, but they could yield other interesting dynamics.…”

Half a century of evolutionary games: a synthesis of theory, application and future directions

“…In biological market interactions, individuals have multiple options to cooperate with a single or multiple partners, such as the interactions on the ‘mating market’ between conspecific males and females, between plants and pollinators, and between ants and lycaenid butterflies. Focusing on the biological market interactions in a marine cleaning mutualism between the marine cleaner wrasse Laboroides dimidiatus and its ‘client’ fishes, Bshary & Noë [30] review how the potential roles of cognition, the means of partner coercion, and the interactions between partner quality and the supply-to-demand ratio affect service quality. While biological market models are generally designed to focus on interactions within a constant environment, evolutionary game theory has been applied to study animals' decision-making across different environments.…”