 The distinction between type recursions and the Price Equation is important, because selection is interpreted differently in each. The two formalisms will issue in different verdicts about whether, and the extent to which, focused selection operates within a single system. If we fix upon a single natural system, and ask how selection operates within it, we will get different answers if we associate selection with fitness variables in type recursions rather than \(\textrm{Cov}(w_{i},z_{i})\) in the Price Equation. To see this, consider how type recursions are structured such that inferences about dynamics over multiple generations may be made by means of them. If fitness coefficients in these models quantify selection, and these take fixed values (as they do in the genotypic selection model considered above and a great many others), then the extent of selection will remain the same over the time period governed by the model: the fitness variables remain at fixed values so selection remains an unchanging influence. But, in just the same cases, the value of \(\textrm{Cov}(w_{i},z_{i})\) in the Price Equation will change across generations as the system evolves: the covariance function in the Price Equation will be highest at intermediate frequencies, when evolution proceeds quickly, and lowest at liminal ones, when evolution goes more slowly. Consider, for instance, the extent to which the population evolves, according to the genotypic selection model above, when the following values are plugged into the model: