Directional, stabilizing and disruptive selection: An analysis of aspects of economic evolution based on Price’s equation

This paper tries to demonstrate that the well developed analysis of directional selection within evolutionary economics can be complemented by analyses of stabilizing selection and disruptive selection. It also tries to demonstrate that the evolutionary algebra provided by Price’s equation increases the intellectual coherence and power of thinking about selection and other aspects of evolutionary processes. The paper combines these aims by analysing the types of selection by means of the algebra of evolution provided by Price’s equation. To prepare for this task, the paper starts by reviewing recent discussions in relation to Price’s equation. This review includes the presentation of framework for analysing evolution that then is used for the definition and analysis of directional, stabilizing and disruptive selection. These types of selection are then related to fitness functions that can produce the different types of selection; and the functions are used for simple simulations of the change of the population distribution of a quantitative characteristic. Finally, Price’s equation is used to decompose the statistics of the changes of the frequency distributions. The changes of mean, variance, skewness and kurtosis are all decomposed as the sum of a selection effect and an intra-member effect. It is especially the signs of these effects that serve to define and characterize the different types of selection. Both this result and the general analysis of the types of selection seem to be of relevance for applied evolutionary economics.