Examining the fitness benefits of social plasticity to prey availability in bottlenose dolphins

Abstract

A key explanation for phenotypic plasticity is that changing behaviour to match conditions increases fitness. Affiliative social associations with conspecifics can be important for coping with challenging conditions, and therefore plasticity in social behaviour in response to environment variation may bring fitness benefits. Here we leverage a dataset of 711 observations of 62 female bottlenose dolphins (Tursiops truncatus) over 35 years to estimate the plastic responses in social behaviour to salmon (Salmo salar) abundance and determine if either this plasticity or their mean social behaviour is associated with lifetime calving success. We found no evidence that mean social behaviour or plasticity in response to salmon abundance were associated with this component of fitness. Female dolphins did not seem to adjust their social behaviour to buffer low, or take advantage of high, salmon abundance and this prey variability was not associated with female reproductive success. Limitations in the data and follow-up simulations suggest that these null relationships, especially for plasticity, may be due to a lack of power, highlighting the difficulty of estimating these covariances even in long term studies with large datasets.