Theory of Fitness in a Heterogeneous Environment. I. The Fitness Set and Adaptive Function

A method is presented for representing the fitness of populations in a heterogeneous environment in terms of their fitness in the various niches taken separately, and the distribution of the niches in space and time. The characteristics of the optimal population can be found for each environmental pattern, and conditions determined in which the optimum is specialized or generalized, mono- or polymorphic, differentiated into discrete races or gradually along clines. These results are shown in table 1. The next paper in this series will extend the model and discuss experimental approaches for testing the theory.