Environmental effects on fitness-sets shape and evolutionarily stable strategies

Most models on the evolution of sex allocation and life-history traits are based on the existence of compensations between these traits, and often consider them as linear. With a simple model of physiological response to richness of the environment, we show that not only can these compensations take many different shapes, but also that this shape varies as a function of the resource level. Consequently, evolutionarily stable strategies (ESSs) calculation can give different results for the same two functions according to resource level. Thus, selection can act in different directions depending on the "quality" of the environment. Moreover, genetic variability in the resource allocation strategies is likely to be shown better in intermediate environments, where the proportions of allocation have the most crucial effect on the phenotype.