Examining cognition in a wild fish species with multiple male phenotypes

Abstract

Research on numeracy, social preferences, and personalities in fishes has contributed to our understanding of the underlying mechanisms and evolution of cognition in animals. Research on fish cognition has been mainly conducted on domesticated, lab-acclimated, or lab-based strains freshwater fish species and a handful of marine fish species. My project explores cognition, specifically memory and individual recognition, in a wild-living Mediterranean marine fish with male alternative reproductive tactics (ARTs): nesting, satellite, and sneaker males. ARTs in this species change over the lifetime of an individual male, rather than by being determined by a genetic polymorphism. Males change in physiology, gene expression, hormone levels and suites of behaviour as they transition through these phenotypes. During the reproductive season, I captured wild-living fish and ran lab-based forced-choice assays to assess their response to a novel object and conspecifics. In a forced-choice assay for familiar versus unfamiliar conspecific females, I found that, nesting males preferred to spend more time with familiar conspecifics but that satellite males made more side switches, a measure of assessment or exploratory behaviour, than nesting males. A forced-choice assay for a familiar versus unfamiliar object revealed no differences in preferences but focal females were significantly faster to explore than sneaker males. In a group size choice assay, all three male types and focal females preferred to spend time with larger groups of conspecific females. These results show that individual recognition and numerical abilities are present in this species. This work contributes to the field of fish cognition by highlighting differences in cognition in a wild-living species with multiple male phenotypes.