The relationship between predator defence behaviour and growth rate in the Pillbug (Armadillidium vulgare)

Animal behaviour is relatively recent field of study amongst biologists and ecologists, and therefore the evolutionary and ecological causes and consequences of behaviour are not yet fully understood. Of particular interest is the idea of animal personalities constituting consistent individual variation in behaviour across contexts and/or over time, and their links to state and life history traits. This study attempted to find a correlation between the life history trait, growth rate, and the personality trait, boldness in the context of predation risk. Boldness refers to an individual’s response to an event, in this case the threat of predation, and as such was measured through latency to end defensive behaviour. The subject of this study, the Pillbug (Armadillidium vulgare) was chosen for its unique and ideal anti-predator reaction, rolling into a protective ball (conglobation). Through an extensive experimental period, we tested the latency of each individual to compare this to each animals growth rate gather over the same period of time. A weak negative correlation was present in the sample population, implying that faster growing individuals were more bold to some degree. This provided an insight into how variation in life history can contribute to predicting behavioural traits and therefore individual reactions to a variety of situations in nature. In future, wider ranging experiments and analyses would provide a much clearer picture of the relationship between these two key variables, and potentially expand our knowledge of ecological and environmental sources of selection in behaviour.