State-dependent social behaviour: modelling behavioural interactions informed by the physiology of the interactors

Organisms have to make decisions about their actions throughout their lives, and these decisions can take many forms. Some can be choices related to key events in their life histories, whilst others are choices about what behaviours to perform from moment to moment. The optimal choice for an organism to perform will depend upon both its internal state (such as their physiology), as well as the state of the environment. Within behavioural ecology, well-characterised techniques exist for identifying consecutive optimal decisions, such as dynamic programming. The decisions made by many organisms are also dependent upon the state and actions of other individuals, which are themselves attempting to optimise their behaviour. Here, I explore a series of dynamic games that consider the social behaviour of pairs of animals, looking at cases where interacting individuals have a common interest and similar rewards. I will also consider what happens when interacting individuals have differing and conflictatory interests, looking at the uneasy alliance between a parasite and its host. These dynamic games give an optimal rule-set for each individual to follow given that it knows its own state and that of its colleagues. I will also consider what happens if this rule-set breaks down, and ask whether simpler rules-of-thumb can be used to approximate optimal behaviour.