title: At odds with the group: changes in lateralization and escape performance reveal conformity and conflict in fish schools.
abstract: Many vertebrates are known to show behavioural lateralization, whereby they differentially use one side of their body or either of their bilateral organs or limbs. Behavioural lateralization often manifests in a turning bias in fishes, with some individuals showing a left bias and others a right bias. Such biases could be the source of considerable conflict in fish schools given that there may be considerable social pressure to conform to the group to maintain effective group evasion. Here, we show that predation pressure is a major determinant of the degree of lateralization, both in a relative and absolute sense, in yellow-and-blueback fusiliers (Caesio teres), a schooling fish common on coral reefs. Wild-caught fish showed a bias for right turning. When predation pressure was experimentally elevated or relaxed, the strength of lateralization changed. Higher predation pressure resulted in an increase in the strength of lateralization. Individuals that exhibited the same turning bias as the majority of individuals in their group had improved escape performance compared with individuals that were at odds with the group. Moreover, individuals that were right-biased had improved escape performance, compared with left-biased ones. Plasticity in lateralization might be an important evolutionary consequence of the way gregarious species respond to predators owing to the probable costs associated with this behaviour.
authors: Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5E2 doug.chivers@usask.ca.
authors: Douglas P
authors: 0000-0002-9497-4329
authors: DP
authors: Chivers
authors: ARC Centre of Excellence for Coral Reef Studies, and College of Marine and Environmental Sciences, James Cook University, Townsville, Queensland 4811, Australia.
authors: Mark I
authors: MI
authors: McCormick
authors: ARC Centre of Excellence for Coral Reef Studies, and College of Marine and Environmental Sciences, James Cook University, Townsville, Queensland 4811, Australia.
authors: Bridie J M
authors: BJ
authors: Allan
authors: Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5E2.
authors: Matthew D
authors: MD
authors: Mitchell
authors: MARE-Marine and Environmental Sciences Centre, ISPA-Instituto Universitário, R. Jardim do Tabaco 34, 1149-041 Lisboa, Portugal.
authors: Emanuel J
authors: EJ
authors: Gonçalves
authors: Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5E2.
authors: Reid
authors: R
authors: Bryshun
authors: Department of Biomedical Sciences, WCVM, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7W 5B4.
authors: Maud C O
authors: MC
authors: Ferrari
mesh_terms: D000818:Animals; D057894:Coral Reefs; D004924:Escape Reaction; D007839:Functional Laterality; D010473:Perciformes / Q000502:physiology*; D011235:Predatory Behavior; D012919:Social Behavior; D013550:Swimming
keywords: alarm cues; behavioural lateralization; coral reef fish; group living; predation; schooling