Data and code from: Social plasticity and individuality shape variation in contest behaviour

Physical contests are critical in most animals in determining access to
limited resources such as territories, food, and sexual partners.
Individuals should base their decision to engage and escalate a contest on
the potential returns and the probability of winning against a specific
opponent. Although variation in competitive ability should maintain
variation in contest behaviour within populations, there is limited
empirical evidence demonstrating that differences in contest behaviour
arise from differences in competitive ability at the individual level.
Here, we used an inbred line of the highly territorial and aggressive fly
Drosophila prolongata to test how pre-existing variation in competitive
ability drives phenotypic variation in contest behaviour. Specifically, we
quantified the degree to which individual differences in two key traits
determining competitive ability, body size and weapon size, contribute to
variation in territoriality and aggressiveness. Although territoriality
and aggressiveness were repeatable, we found that behavioural plasticity
in response to both focal and opponent morphological traits largely
explains variation in both behaviours. Thus, even in the absence of
genetic differences and under identical laboratory conditions, individuals
consistently differ in contest behaviour while still adjusting their
responses to the social context. We suggest that variation in the
micro-environment, by shaping competitive ability through body size and
weapon size, plays a crucial role in driving both between-and within
individual variation in social behaviour.