Living in Groups 2

Collective BehaviourDr Andrew JacksonZoologySchool of Natural SciencesTrinity Centre for Biodiversity ResearchTrinity College Dublin1Examples from Cells to Beasts

2Advantageous Information Transfer

3Collective Behaviourhttp://vimeo.com/311588414Complex Social Environment

5from simple individuals.

How do we get to complex groups?

6The basic rulesPersonal space - cant occupy the same space as someone elseImitation - tend to copy others and will seemingly follow another without promptingGregarious they dont like being on their own, so will move towards others if isolated

7Blind SpotIndividual Based Model (IBM)RepulsionOrientationAttraction8Local Interactions9Collective behaviourEmerges as a result of interactions between individual agents.

Properties of the group are not encoded directly by behaviours at the individual level.

Patterns emerge through self-organisation of the system10Matlab example11Sensitivity to individual behavioursVary only the zone of orientationBlind Spot12SwarmingSmall zone of orientation13Matlab Swarms

14Torus (ring-doughnut) patternsIntermediate zone of orientation15Matlab Torus

16College Park Torus17Directed ShoalLarge zone of orientation18Matlab Directed Shoals

19Variation in behaviourMatlab example (swim speed)Individuals are different20Fast-slow video21Finding your way around your groupFastLarger zone of repulsionHigh Rate of Turning22Subtle behavioural changesGives evolution an easy (well easier) way to effect dramatic change at the group level patternKey concept in developmental biologyDont need complex cognitive processing and rules to navigate and negotiate the group complex23But clearly some individuals do have informationCollective Decision Making24Coercion is easy25 but depends on numbers26Few informed individualsCrowd video few informed individuals27Many informed individualsCrowd video many informed individuals

28Conflict of informationCrowd video conflict of information

29Few individuals can sway a groupOnly a small proportion of informed individuals needed to influence the crowdLarger groups need smaller proportion of informed individuals reach a collective decision

30ConclusionsComplex collective behaviour derived from local interactions between individuals.

Group level properties emerge the whole is greater than the sum of its parts.

Need to take a holistic approach to these systems.31Suggested ReadingDyer, J. R. G., Johansson, A., Helbing, D., Couzin, I. D., & Krause, J. (2009). Leadership, consensus decision making and collective behaviour in humans.Philosophical Transactions of the Royal Society B: Biological Sciences, 364(1518), 781-789. [pdf] Couzin, I. D. (2007). Collective minds.Nature, 445(7129), 715-715. [pdf]Couzin, I. D. (2006). Behavioral Ecology: Social Organization in Fission-Fusion Societies.Current Biology, 16(5), r169-r171. [pdf]Couzin et al. 2002. Collective memory and spatial sorting in animal groups. J Theor Biol. 218, 1-11. doi

I suggest you watch this short 5 minute video about collective behaviour by Prof Iain Couzin http://youtu.be/_2WqH_HUxz8 , and basically anything Iain publishes is pretty cool by me http://icouzin.princeton.edu/And the starlings are always worth viewing - http://vimeo.com/31158841

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