Invasive species can cause significant economic and ecological damage in their new home. Focused preventive measures are difficult unless we know what makes invasions succeed. We have some answers; but the role of behaviour is not yet settled - especially inter-individual behavioural variation within species. This Project will uncover how and why such variation assists invasion. Using a known invasive reptile model, it will determine experimentally which relevant behaviours are heritable, and therefore subject to evolutionary selection during introduction, establishment, and spread into new locations. As a theoretical and very practical outcome, we will understand better why some species repeatedly succeed in invading, while others fail.