Cognition in Multi-species Sociality

The natural world is filled with interspecies relationships that extend beyond the more familiar predator-prey dynamics. Indeed, individuals of different species can engage in complex associations to gain - either supplementary or complementary - benefits in various ecological contexts. Supplementary benefits occur, for instance, in mixed flocks or shoals formed by different species of birds or fish with similar appearances. These associations support the formation of larger units, thereby reducing the chances of predation for each individual within the group (dilution effect). In contrast, complementary benefits tend to arise from role specialization of species with different morphologies, sensory adaptations and/or behavioural strategies. These partnerships contribute to the overall fitness of the individuals involved, yet through distinct advantages depending on the specific role played by the partner species. This primer provides a guide to how cognition can influence complex interspecies interactions, exploring both proximate mechanisms (the immediate processes) and ultimate factors (the evolutionary impact) behind these relationships.