1. Collective Behaviour Dr Andrew Jackson Zoology School of Natural Sciences Trinity Centre for Biodiversity Research Trinity College Dublin

2. Examples from Cells to Beasts

3. Advantageous Information Transfer

4. Collective Behaviour http://vimeo.com/31158841

5. Complex Social Environment

6. from simple individuals…. How do we get … to complex groups?

7. The basic rules 1.Personal space - cant occupy the same space as someone else 2.Imitation - tend to copy others and will seemingly follow another without prompting 3.Gregarious – they don’t like being on their own, so will move towards others if isolated

8. Blind Spot Individual Based Model (IBM) Repulsion Orientation Attraction

9. Local Interactions

10. Collective behaviour Emerges 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 system

11. Matlab example

12. Sensitivity to individual behaviours Vary only the zone of orientation Blind Spot

13. Swarming Small zone of orientation

14. Matlab Swarms

15. Torus (ring-doughnut) patterns Intermediate zone of orientation

16. Matlab Torus

17. College Park Torus

18. Directed Shoal Large zone of orientation

19. Matlab Directed Shoals

20. Variation in behaviour Matlab example (swim speed) Individuals are different

21. Fast-slow video

22. Finding your way around your group Fast Larger zone of repulsion High Rate of Turning

23. Subtle behavioural changes Gives evolution an easy (well easier) way to effect dramatic change at the group level pattern – Key concept in developmental biology Don’t need complex cognitive processing and rules to navigate and negotiate the group complex

24. But clearly some individuals do have information… Collective Decision Making

25. Coercion is easy

26. … but depends on numbers

27. Few informed individuals Crowd video – few informed individuals

28. Many informed individuals Crowd video – many informed individuals

29. Conflict of information Crowd video – conflict of information

30. Few individuals can sway a group Only a small proportion of informed individuals needed to influence the crowd Larger groups need smaller proportion of informed individuals reach a collective decision

31. Conclusions Complex 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.

32. Suggested Reading Dyer, 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]pdf Couzin, I. D. (2007). Collective minds. Nature, 445(7129), 715-715. [pdf]pdf Couzin, I. D. (2006). Behavioral Ecology: Social Organization in Fission-Fusion Societies. Current Biology, 16(5), r169-r171. [pdf]pdf Couzin et al. 2002. Collective memory and spatial sorting in animal groups. J Theor Biol. 218, 1-11. doidoi 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/http://youtu.be/_2WqH_HUxz8http://icouzin.princeton.edu/ And the starlings are always worth viewing - http://vimeo.com/31158841http://vimeo.com/31158841