BIO150Y: Evolution of Cooperation Evolutionary Game

Expt. 1: Do cheats always predominate over suckers?

Your Objective

Conduct simulations of the population which starts with 15 cheats (ALLD) and 15 suckers (ALLC) and determine whether evolution occurs and, if so, which strategy tends to predominate.

Suggested Methods

  • Run at least five replicates of the experiment.
  • You can download a worksheet (as a PDF file) which contains data tables to record your results.
  • Based on your results, answer the quiz questions below.


  • Each coloured graph line tracks the number of players for each strategy through the 20 generations that the experiment takes.
  • Point+click on Reset to set up each new replicate experiment.


Based on your results, answer the following questions:

If the population was initially composed of 15 ALLC individuals and 15 ALLD individuals what was the starting frequency of the sucker strategy in the population?

In your simulations of a population composed of ALLD and ALLC individuals what evidence, if any, was there that evolution occurred?

In general, what is the expected long-term outcome for a population composed of cheats and suckers?

" Do your results mean that a nasty strategy like cheat will always dominate nice strategies? Let's see how some other nice strategies do against nasty strategies..."

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