Character Study

Antisocial fish are more likely to invade new environments

Personality questionnaireWhat makes an animal inclined to stake out new territory, leading biological invasions that can harm native wildlife? A study in Proceedings of the Royal Society B suggests that personality can play a role.

A team administered personality tests to mosquitofish (Gambusia affinis), a species currently ranked as one of the worst invaders in the world. Each fish was scored on its sociability, measured by how long it spent swimming close to a group of fellow fish in an aquarium. Researchers also scored traits such as boldness, or how quickly the fish emerged from a refuge to explore a new environment.

After assessing each fish’s personality, the researchers placed groups of fish into one end of an artificial stream containing five connected pools. Individuals that had scored low on sociability swam farther, often reaching the fourth or fifth pools. In contrast, most other fish remained in the first pool, the team found.

A mosquitofish’s personality therefore may influence whether it will lead an invasion, the researchers say. And having multiple personality types within a species could allow an invasion to spread faster. Social individuals might eventually follow the leaders to their new territory, increasing the population density and prompting the loners to strike out on their own again. – Roberta Kwok

Source: Cote, J. et al (2010). Personality traits and dispersal tendency in the invasive mosquitofish (Gambusia affinis) Proceedings of the Royal Society B DOI: 10.1098/rspb.2009.2128

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