By Pawel Romanczuk (Berlin, Germany).

Collective behavior of animals is a fascinating example of self-organization in biology, which together with the underlying social interactions are believed to have emerged from evolutionary adaptations. Thus, it is widely assumed that collective behavior confers fitness benefits to individuals, for example by enabling exchange of social information, promoting accurate collective decisions, or conferring protection from predators. In this context, it has been argued that animal collectives should operate in a special parameter region close to critical points [1], where various aspects of collective computations become optimal [2]. Here, we will investigate the “criticality hypothesis” in the context of collective predator response in fish. First, using a spatially explicit model of fish schools interacting with predator agents, we will explore the optimality of the order-disorder transition in collective movement, and whether individual-level evolutionary adaptation can lead to self-organization towards criticality [3]. Second, by combining experiments in a controlled laboratory setting with computational models, we will explore the spreading of fast escape responses in fish schools, so called startle cascades, analogous to neuronal avalanches and discuss potential costs and benefits of being (sub)-critical [4]. Lastly, we will present our work on analysis and modeling large-scale startle waves in fish schools subject to high predation pressure under natural conditions in the wild [5].


[1] T. Mora, W. Bialek: Are biological systems poised at criticality?. Journal of Statistical Physics 144, 268-302 (2011)

[2] M.A. Munoz: Colloquium: Criticality and dynamical fast scaling in living systems.” Reviews of Modern Physics 90, 031001 (2018) [3] P.P. Klamser, P. Romanczuk: Collective predator evasion: Putting the criticality hypothesis to the test. PLoS Computational Biology 17, e1008832 (2021)

[4] W. Poel, B.C. Daniels, M.M. Sosna, C.R. Twomey, S.P. Leblanc, I.D. Couzin, P. Romanczuk: Subcritical escape waves in schooling fish. Science Advances, 8, eabm6385 (2022)

[5] L. Gómez Nava, R. T. Lange, P. P. Klamser, J. Lukas, L.A. Rodriguez, D. Bierbach, J. Krause, H. Sprekeler, P. Romanczuk: Fish schools maximize sensitivity towards external cues and show optimal information spread at criticality, in revision (2022)

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