Influence of Reproductive Cycle and Environmental Stress on Personality in Threespine Stickleback (Gasterosteus aculeatus)

Date of Award


Degree Type


Degree Name

Master of Science in Biology

Chief Instructor

Susan A. Foster

Second Reader

John A. Baker

Third Reader

Neva Meyer


Personality traits, such as boldness and exploratory behavior, are likely targets of selection as they can impact a myriad of significant behaviors, including dispersal, dominance, foraging, and antipredator behavior, each of which can influence reproductive success and survival, ultimately influencing fitness. Many aspects of an environment, including predator threat intensity and social setting can shape the overall personality within a population. Here we investigated and will discuss personality of male and female threespine stickleback (Gasterosteus aculeatus) by considering behavioral responses when introduced to a novel environment and after a predatory attack during distinct stages of their reproductive cycle. We consider populations representing variation in levels of social cannibalism. Because cannibalism intensity has altered reproductive behavior in these populations, we predicted population level differences in personality associated with levels of cannibalism. Further, the reproductive stages investigated represent time points that correspond with natural changes in behavior, and thus we hypothesized that correlated shifts in personality would be detected. Our results suggest that the ancestral oceanic population significantly varied from the two freshwater populations in both activity level and relative risk to a predator. Ovulated females were relatively more active than those early in their clutch production, while retaining a clutch for an additional 24 hours resulted in the least bold behavior. Males were found to be relatively bolder than females, but only when they were acclimated to the environment. All populations and both sexes reacted similarly to the stressful conditions (lowered boldness)