Individual differences and unpredictability in escape behavior

Phenotypic variation occurs in a hierarchical pattern, with differences occurring among species, populations, individuals and instances. In animal behavior, within-individual variation can be determined by environmental factors or be a stochastic component of behavioral strategies. The latter is particularly important in prey-predator interactions. Prey that behave predictably are more easily targeted by predators. By introducing unpredictable elements in their behavior, prey can evade predators effectively. However, despite its importance in influencing individual fitness, the causes and consequences of unpredictability have been historically overlooked in evolutionary theory. The research presented in this dissertation focuses on escape behavior in steppe grasshoppers Chorthippus dorsatus. Grasshoppers are important prey animals, and employ escape strategies that differ among individuals, including differences in unpredictability levels. By phenotyping the escape behavior of individuals multiple times, I was able to decompose the importance of variables affecting behavioral differences among and within individuals. I found that individuals experiencing poor health conditions can reduce their unpredictability levels, implying that unpredictability may not be accidental but rather a deliberate and valuable behavioral trait. Individuals also showed consistency in their levels of unpredictability across life stages, while differences among individuals increased, suggesting that unpredictability in escape behavior could be considered an aspect of animal personality. I also identified a genetic basis for escape strategies, meaning that they can be a target of selection and have the potential to evolve. This dissertation contributes to the growing understanding of unpredictability in animal behavior and highlights the complexity of behavioral variation and its ecological and evolutionary implications.