HEA STEM 2014

Understanding evolutionarily stable strategies: interactive games in the classroom

Catherine Dennis

Evolutionarily Stable Strategy?

‘A strategy which, if adopted by a population in a given environment, cannot be invaded by any alternative strategy that

is initially rare.’

Pure ESS

One strategy adopted by all animals

Mixed ESS

Frequency dependent

Aim

John Maynard Smith (1973)

Hawk Dove Game

Hawk Dove Game

Fight – win or be injured

Win

Retreat Negotiate peacefully

HAWK DOVE

HAWK

DOVE

Hawk Dove Game

Fight – win or be injured

Win

Retreat Negotiate peacefully

HAWK DOVE

HAWK

DOVE

Hawk Dove Game

Victory - Cost

2Victory

0Victory

2

HAWK DOVE

HAWK

DOVE

To play the game:

Victory = 50 points, Cost = -100 points

Victory = 50 points, Cost = 0

50 points 0 points

Hawk Dove Game

To play the game:

Victory = 50 points, Cost = -100 points

Victory = 50 points, Cost = 0

50 points 0 points

10 rounds

Hawk Dove Game

Hawk Dove Game

Hawk Dove Game

Hawk Dove Game

Hawk Dove Game

Hawk Dove Game

Hawk Dove Game

V - C2

V

0V2

HAWK DOVE

HAWK

DOVE

-25 50

0 25

Benefits

• Not entirely equation focussed• Play both strategies – one species!

• Evolutionary nature of the game emphasised• ACTIVE

Limitations

• Some students still fail to grasp concept

However…..

…..they remember game theory

….. all appear to be comfortable with the concept by Level 4

Further activities

• Spreadsheet exercises in ecology and evolution chapter 39: Evolutionary Stable Strategies http://www.uvm.edu/rsenr/vtcfwru/spreadsheets/ecologyevolution/ecology_evolution.htm

• Dennis, C. (2014) Teaching the repeated Prisoner’s Dilemma with a non-computerised adaptation of Axelrod’s Tournament, Journal of Biological Education (in press)

• Extension exercise for Axelrod’s Tournament: http://www.christopherxjjensen.com/research/projects/online-cooperative-resource/easy-iterated-prisoners-dilemma/