Evolutionary physiology of the cost of reproduction

The concept of a cost of reproduction has associations with a variety of ot her ideas in population biology, among them trade-offs and antagonistic ple iotropy. Within the concept of a cost of reproduction, a variety of compone nts can be distinguished, such as physiological and ecological costs of rep roduction. This article concentrates on the former type of cost. Empiricall y, a variety of approaches can be, and have been, used to analyze the cost of reproduction. Three are distinguished: genetic, environmental, and physi ological. These are discussed first in general terms and second with specif ic reference to research on laboratory evolution in Drosophila. The latter discussion serves to focus and to instantiate the general analysis of the f ield. Emerging themes from this area of research include the environmental plasticity of costs of reproduction, the difficulties facing simple trade-o ff theories, and the critical role of physiological integration in determin ing costs at the organismal level.