Book contents
- Frontmatter
- Contents
- Preface
- 1 Introduction
- 2 The basic model
- 3 The war of attrition
- 4 Games with genetic models
- 5 Learning the ESS
- 6 Mixed strategies – I. A classification of mechanisms
- 7 Mixed strategies – II. Examples
- 8 Asymmetric games – I. Ownership
- 9 Asymmetric games – II. A classification, and some illustrative examples
- 10 Asymmetric games – III. Sex and generation games
- 11 Life history strategies and the size game
- 12 Honesty, bargaining and commitment
- 13 The evolution of cooperation
- 14 Postscript
- Appendixes
- Explanation of main terms
- References
- Subject index
- Author index
7 - Mixed strategies – II. Examples
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- Preface
- 1 Introduction
- 2 The basic model
- 3 The war of attrition
- 4 Games with genetic models
- 5 Learning the ESS
- 6 Mixed strategies – I. A classification of mechanisms
- 7 Mixed strategies – II. Examples
- 8 Asymmetric games – I. Ownership
- 9 Asymmetric games – II. A classification, and some illustrative examples
- 10 Asymmetric games – III. Sex and generation games
- 11 Life history strategies and the size game
- 12 Honesty, bargaining and commitment
- 13 The evolution of cooperation
- 14 Postscript
- Appendixes
- Explanation of main terms
- References
- Subject index
- Author index
Summary
It would be satisfying if one could go through the classification in Table 10 (p. 78), and give examples of each category. Unfortunately, even when it is known that an individual retains the same pure strategy throughout life, there is rarely any direct evidence for genetic involvement; hence it is impossible to distinguish categories I and IIa. If individuals are known to switch tactics during their lifetimes, and if it can be shown that payoffs for different actions are equal, it may still be difficult to distinguish between IIb, III and IV. I shall therefore discuss a series of examples of variable behaviour, loosely grouped according to the context in which they occur.
The sex ratio
Some of the mechanisms listed in Table 10 can be nicely illustrated by the evolution of the sex ratio. In Chapter 4 section B, it was supposed that the sex ratio is determined by genes acting in one or other parent. This is equivalent to treating it as a game played by females (or by males), each of which is attempting to maximise the number of grandchildren produced. In the simplest case (sons and daughters cost the same; no population structure) the ESS is a 1:1 ratio. This can be achieved in two ways. Most commonly, as in birds, mammals and Drosophila, there is random segregation of X and Y chromosomes in the meiosis of one or other parent.
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- Evolution and the Theory of Games , pp. 81 - 93Publisher: Cambridge University PressPrint publication year: 1982