Understanding natural selection: an approach integrating selection gradients, multiplicative fitness components, and path analysis

Abstract

A variety of methods for measuring natural selection have been introduced recently, spurring a large number of empirical studies. Each method has its own strengths and weaknesses, and the use of different techniques in different ways has hampered comparisons among studies. I outline a method for integrating selection gradients, multiplicative fitness components and path analysis in a standardized way, to utilize the strengths of each technique and facilitate comparisons among studies. First, selection gradients are calculated using total lifetime fitness; these estimates can be used in equations to predict evolutionary change. Second, path analysis and multiplicative fitness components are used to understand the causes of selection. Examples of the method applied to studies of selection in an animal and a plant are given; use of this method allows comparisons to be made between the two studies of disparate taxa.