BIO150Y: Evolution of Cooperation Evolutionary Game

Background to your experiments

What is an Evolutionary Prisoner's Dilemma Game?

Populations are composed of individuals who use different strategies in social interactions. If the success of a strategy in the game results in more individuals using that strategy in the next generation, then the composition of strategies in a population will change through time -- thus we can expect the evolution of strategies.

Define evolution

      Charles Darwin (1809-1882)
How the Evolutionary Game works

  • Individuals pair up randomly and play multiple-moves games.
  • Player points are tallied and the totals for each strategy calculated.
  • The number of players for each strategy in the next round (generation) of games is based on the relative success of each strategy in the previous generation.
  • A new round of games are played. The graph plots the number of players for each strategy at each generation.
Calculating relative success

Try these Exercises
Here are three experiments which have been set up for you to investigate the success or failure of different strategies when they co-exist and interact with each other in a population.
Expt. 1: Do cheats always do better than suckers?

Expt. 2: Can nice strategies beat out nasty strategies?

Expt. 3: Can Tit for Tat succeed in a population of cheaters?

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