Evolution of Conditional Cooperation

  • Philip Madgwick

Student thesis: Doctoral ThesisPhD


Cooperation presents evolutionary theory with an interesting puzzle: why should an actor help a recipient? Evolutionary explanations of cooperation rely on finding ways through which cooperative behaviour benefits the actor, by considering the selection on a gene for cooperation. A critical variable is the relatedness between the actor and the recipient, which determines the probability that they share the gene for cooperation. Consequently, a classic expectation is that an actor should only cooperate on the condition that the relatedness between the actor and the recipient ensures a net gain for the gene for cooperation. However, such conditional cooperation has been dismissed as an unimportant part of the evolutionary theory of cooperation because the simpler explanation of unconditional cooperation is usually sufficient. The scepticism of the relevance of conditional cooperation is often based on two premises: first there is very little evidence of its importance, and second conditional cooperation lacks a plausible mechanism for its operation and persistence. In this thesis by publication, I provide a rebuttal using experimental evidence of conditional cooperation in the social amoeba Dictyostelium discoideum, developing theoretical models to examine the possible mechanisms for conditional cooperation and comparatively situating these arguments within the broader context of other study systems. Using five papers (and a comment on each), I present the case that conditional cooperation should not be so easily dismissed, as it seems likely to be a more important part of the evolutionary explanation of cooperation in nature than current evidence might suggest.
Date of Award19 Nov 2019
Original languageEnglish
Awarding Institution
  • University of Bath
SupervisorAraxi Urrutia (Supervisor) & Jason Wolf (Supervisor)


  • Evolution
  • Genetics
  • Behaviour
  • Game theory

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