The importance of intraspecific frequency-dependent selection in modelling competitive coevolution

Summary The coevolution of competitors has been analyzed by two different types of fitness-maximization techniques; ESS methods (Lawlor and Maynard Smith, 1976), and CSS methods (Roughgarden, 1979). This paper argues that CSS methods generally do not predict the outcome of competitive coevolution. Even when there is relatively little variability within species, fitness maximization leads to an ESS rather than a CSS. A simple model is analyzed to show that ESS and CSS predictions about character displacement can differ qualitatively. Previous results of CSS analyses are discussed.