Variation in Cleaner Wrasse Cooperation and Cognition: Influence of the Developmental Environment?

Abstract

Deviations from model-based predictions of strategies leading to stable cooperation between unrelated individuals have raised considerable debate in regards to decision-making processes in humans. Here, we present data on cleaner wrasse (Labroides dimidiatus) that emphasize the importance of generalizing this discussion to other species, with the aim to develop a coherent theoretical framework. Cleaners eat ectoparasites and mucus off client fishes and vary their service quality based on a clients' strategic behaviour. Hitherto, cognitive tasks designed to replicate such behaviour have revealed a strong link between cooperative behaviour and game theoretic predictions. However, we show that individuals from a specific location within our study site repeatedly failed to conform to the published evidence. We started exploring potential functional and mechanistic causes for this unexpected result, focusing on client composition, cleaner standard personality measures and ontogeny. We found that failing individuals lived in a socially simple environment. Decision rules of these cleaners ignored existing information in their environment ('bounded rationality'), in contrast to cleaners living in a socially complex area. With respect to potential mechanisms, we found no correlations between differences in performance and differences in aggressiveness or boldness, in contrast to results on other cooperative species. Furthermore, juveniles from the two habitat types performed similarly, and better than the adults from the socially simple environment. We propose that variation in the costs and benefits of knowledge may affect a cleaners' information acquisition and storage, which may explain our observed variation in cooperation and cognition.

Learning and Behavior in Reef Fish: Fuel for Microevolutionary Change?

“…In the Wismer et al. () study, we see that populations of Labroides on continuous reefs, where clients have options of many different cleaner stations, were less likely to cheat and adhered to the behavioral predictions made by game theory. By contrast, those found on patch reefs cheated more than expected.…”

“…The Wismer et al. () paper does not fully address whether this scenario is happing in Lizard Island, and further research, including common tank experiments, would go far to fully exploring this tantalizing situation. However, we wish to take this opportunity to explore a thought experiment that highlights the importance of behavior, natural history observations, and learning can have in explaining the vivid spender of coral reef diversity.…”

“…In a recent piece, Wismer et al. () demonstrated learned behavioral differences between two groups of a common reef fish Labroides dimidiatus (Labridae) living in different habitats, patch reefs, and continuous fringing reefs. In our piece, we aim to use the fascinating observational and experimental work performed by Wismer et al.…”

“…In a recent piece, Wismer et al (2014) demonstrated learned behavioral differences between two groups of a common reef fish Labroides dimidiatus (Labridae) living in different habitats, patch reefs, and continuous fringing reefs. In our piece, we aim to use the fascinating observational and experimental work performed by Wismer et al as an entry point into how learned behaviors could potentially join biogeography and behavior as mechanisms explaining the observed diversity of reef fish population structure.…”

Animal behaviour: Inside the cunning, caring and greedy minds of fish

“…To Bshary's surprise, the cleaner fish there turned out to be much less socially smart than cleaner fish just 20 metres away 9 . But their skill level may be optimal for their environment -another hypothesis that he now plans to explore.…”