The payoffs for player 1 adopting the dove strategy against a hawk and against a dove are in the lower left and lower right quadrants, respectively. If player 1 is a hawk and encounters a dove, the payoff for player 1 is B, the value in the upper right quadrant. In the matrix, the payoffs typically are those assigned to the player depicted in the row playing against the strategy in the column thus, in Figure 1a, if player 1 is a hawk, and encounters a hawk, the payoff for player 1 is ½ (B-C), the value in the upper left quadrant. 1a), in which the payoff for the individual involved is shown for all possible interactions. Furthermore, stable payoff equilibriums have been shown for cooperation and altruism, behaviors that seem contradictory to the strongly supported individualistic, survival of the fittest mode of evolution 3.Įvolutionary games are often visually represented as a payoff matrix (Fig. Estimating fitness for strategies based on the payoff matrix reveals stable payoff equilibriums may be achieved through natural selection, an important feature of evolutionary game theory. While much of game theory is based on the interactions of rational decision makers (humans), in evolutionary game theory the payoff is a surrogate for fitness and strategies evolve over many repeated iterations of the game 2,3. An individual does not control the decisions of others. Game theory is a branch of mathematics that investigates the outcomes of multi-individual interactions, in which the payoff for any one individual depends not only on its own strategy, but the strategies of the other individuals involved. Since biological interactions involve two or more decision makers (i.e., individuals with strategies), biologists utilize game theory to elucidate evolutionary consequences of interactions 1. Interactions between organisms with either competing or identical strategies can be treated as games with multiple players.
Since the interaction strategy (phenotype) can directly relate to fitness, the optimum strategy will be favored under natural selection. In short, the organism with the best interaction strategy has the highest fitness.
The most successful organisms maximize their payoff and increase their ability to reproduce. Evolutionary ecologists treat these strategies as phenotypes. Different interaction strategies, such as combative or cooperative, result in different payoffs based on nature of the interaction. Comparing the relative cost to the benefits obtained following an interaction determines the net gain or loss incurred by the organism, and this value is referred to as the payoff. The energy spent is a cost to the organism, and the resources are benefits. Indeed, even avoidance can be costly if energy is expended and no resources are obtained. Interactions are costly: energy is invested by each organism in both confrontation and cooperation as a means to acquire the resource. In general, these interactions range from antagonistic to cooperative, but cases of exploitation and altruism also occur. Evolutionary ecologists aim to understand the complex behavioral relationships between organisms as they interact to obtain resources.
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