Emily McHenry Biology 478 April 25, 2012 COLLECTIVE DECISION MAKING: SYNCHRONOUS MOVEMENT OF INDIVIDUALS IN GROUPS

WHAT IS COLLECTIVE BEHAVIOR? feature=related (Start at 3:37)

Collective animal behavior: the coordinated behavior of large groups of similar animals and the emergent properties of these groups (Couzin 2012). WHAT IS COLLECTIVE BEHAVIOR? worldhum.com

 Flocks of birds  Swarms of insects  Schools of fish  Herds of mammals EXAMPLES OF COLLECTIVE BEHAVIOR aquariumprosmn.com esa.orgdigital-photography-school.com

 Increased foraging efficiency (Bazazi 2012)  Energy efficiency (Tamm 1980)  Aerodynamic and hydrodynamic benefits  Predation avoidance  Relies on selfish herd effect; increased group size results in lower chances of any one individual becoming a victim WHY DO ANIMALS MOVE SYNCHRONOUSLY?

 There are 3 Distinct patterns of predation avoidance  Vacuolization:  where expansion results in a cavity forming around the predator  Flash expansion:  where individuals rapidly move away from the predator as it strikes  Split effect  where the group fragments  Most common reason for aggregations, but not always beneficial!  PREDATION AVOIDANCE

 Most research has been done in two ways: 1.Filming groups and then frame- by-frame analyzing 2.Swarm simulating software STUDYING COLLECTIVE BEHAVIOR princeton.edu

SWARM SIMULATIONS GUkjC-69vaw  Swarms are created following 3 fundamental rules :  Separation: steer to avoid crowding or collisions  Alignment: steer toward the average heading of groupmates  Cohesion: steer to move toward the average position of local groupmates

 Previously thought to be telepathic  Utilizing senses  Eyesight, pressure, hearing, etc.  Monitoring position of neighbors  Behavioral zones  Repulsion  Attraction  Alignment based on relative position HOW DO ANIMALS MOVE SYNCHRONOUSLY?

 Flocking Birds/Schooling Fish  Democracy  Quorum responses (Sumpter 2009)  Insects  No leader, forced march (Simpson 2006)  Mammals  Unknown DECISION MAKING IN THE GROUP

QUESTIONS?

 Potts, Wayne K "The chorus-line hypothesis of coordination in avian flocks." Nature 24:  Simpson, Stephen J, Gregory A. Sword, Patrick D. Lorch, and Iain D. Couzin. "Cannibal Crickets on a Forced March for Protein and Salt." Proceedings of the National Academy of Sciences of the United States of America (2006):  Bazazi, S. et al. (2012) Vortex formation and foraging in polyphonic spadefoot toad tadpoles. Behavioral Ecology and Sociobiology. March  Tamm, Staffan. "Bird Orientation: Single Homing Pigeons Compared with Small Flocks." Behavioral Ecology and Sociobiology. 7.4 (1980):  Tien, J Rubenstein, D. “Dynamics of fish shoals: Identifying key decision rules.” Evolutionary Ecology Research, No. 6. (2004), pp  Ward, A.J.W, D.J.T Sumpter, I.D Couzin, P.J.B Hart, and J Krause. "Quorum Decision-Making Facilitates Information Transfer in Fish Shoals." Proceedings of the National Academy of Sciences of the United States of America (2008):  Sumpter, D.J.T, and S.C Pratt. "Quorum Responses and Consensus Decision Making." Philosophical Transactions of the Royal Society B: Biological Sciences (2009):  Couzin, I D, and J Krause. "Self-organization and Collective Behavior in Vertebrates." Advances in the Study of Behavior. 32 (2003):  Couzin, I. D., J. Krause, R. James, G. D. Ruxton, and N. R. Franks Collective memory and spatial sorting in animal groups. Journal of Theoretical Biology 218:  Caraco, T., S. Martindale, and H. R. Pulliam Flocking: advantages and disadvantages. Nature 285: WORKS CITED