Personality Matters: Individual and Population-Level Personality Traits Influence Dispersal Decisions in the Invasive Western Mosquitofish (Gambusia affinis)

Invasive species can have major ecological and economic impacts, making understanding and predicting ecological invasions a critical research goal. Recent work has suggested that a key mechanism influencing invasion dynamics is personality-dependent dispersal. We examined how individual personality type and the average personality of the source population influence dispersal decisions in the invasive mosquitofish (Gambusia affinis). We measured sociability, boldness, activity, and exploration tendency in individually marked mosquitofish in the lab and measured dispersal tendencies in outdoor artificial streams. Mosquitofish behaviors are consistent over at least a four month period, and stable correlations exist between behaviors. Social behavior arose as an important predictor of the decision to disperse at the individual and population level. Individuals who were more asocial were more likely to disperse. Additionally, individuals from populations that are, on average, more asocial or more bold are more likely to disperse regardless of their own personality type. Our results suggest that individual and population level behavioral traits are important for understanding the spread of invasive species.