Causes and consequences of social behavior variation: implications for the evolution of cooperative behavior in a marine environment

Cleaner fish remove ectoparasites, dead tissue or mucus of other fish species, known as clients, who visit the territory of the cleaner fish, i.e. the cleaning station. A cleaner fish is classified as an obligatory cleaner when it cleans other fish throughout its whole life cycle, and as facultative when cleaning occurs only in juveniles or as an alternative behavior in adulthood. The species Elacatinus prochilos is classified as a facultative cleaner that alternate its feeding behavior in adulthood. The species exhibit two alternative behavioral strategies: (i) coral-dwelling individuals, usually found in pairs or small groups, that depend on cooperative cleaning interactions for feeding or (ii) sponge-dwelling individuals, organized in larger groups with dominance hierarchies, which feed on micro - organisms living inside the sponges tissue. The aim of this study is to investigate the physiological and behavioral mechanisms (proximate causes), and the costs and benefits (ultimate causes) associated with the intra-specific behavioral variation.