Proc. R. Soc. B doi:10.1098/rspb.2009.2128 (2010)

Invasive species can have devastating effects on the ecosystems that they encroach upon. Experiments on mosquitofish (Gambusia affinis), considered one of the world's worst invasive species, suggest that an individual's personality may influence its tendency to disperse and form invasive colonies.

Julien Cote and his colleagues at the University of California, Davis, measured four personality traits in the fish: sociability, boldness, activity and exploration. For example, sociability was measured as the amount of time spent by a fish in close proximity to a group of strangers in a new environment. The team then examined how far individuals dispersed from their initial release point in an experimental stream, and found that the more asocial fish travelled farther. The authors say that invaders may have distinct personalities that could help to explain their often negative ecological effects.