SUBCRITICAL COLLECTIVE ESCAPE WAVES IN FISH
Institute for Theoretical Biology, Humboldt Universität zu Berlin, Berlin, Germany
Living systems such as neural networks or animal groups process
information about their environment via the dynamics of many interacting
units and show transitions between sets of distinct macroscopic
behaviors. While many studies focus on the idea that for biological
systems being close to such a transition (or critical point) optimally
manages a trade-off between desired functions of the macroscopic
behaviors it separates, or that it yields optimal computational
abilities, little attention has been given to the fact that the
`optimal' configuration will depend on the environmental context. Here,
we combine experimental evidence and computer simulations to show that
for escape waves in schooling fish the distance to a critical point is
changed via a modulation of school density according to group members'
perceived risk of the environment. We find that the observed escape
waves are spreading subcritically making the schools collective response
less sensitive to cue intensity but more robust towards false alarms
than at the critical school density.