This volume is the result of a symposium entitled "Variation in Life Histories: Genetics and Evolutionary Processes" sponsored by the Program in Evolutionary Ecology and Behavior ofthe University of Iowa and held in Iowa City on October 13 and 14, 1980. Prompted by arecent upsurge of interest in the evolution of life histories, we chose this topic because of the obvious association between life history traits and Darwinian fit ness. If such an association were to be fruitfully investigated, it would require the eloser cooperation of population and evolutionary ecologists and quantitative and population geneticists. To encourage such an association, our symposium had four major aims: first, to facilitate intellectual exchange across disciplines among an array of biologists studying life histories; second, to encourage exploration of genetic variance and covari ance for life history traits; third, to consider the ecological background for genetic vari ability; and finally, to facilitate a comparative overview both within and among species. Obviously such broad aims cannot be met totally in a single volume, but we think we have succeeded reasonably wen in providing a representative and nourishing intel lectual feast. We see this book as a stimulus to the coordination of future efforts in an important and expanding area of inquiry. We have divided the book into six sections.

Introductory Chapter: Genetics, Ecology, and the Evolution of Life Histories

Introductory Chapter Genetics, Ecology, and the Evolution of Life Histories
Theory
Some Theoretical Considerations Concerning Life History Evolution
Elements of a Quantitative Genetic Model of Life History Evolution
Physiological Adaptation
Models for Physiological and Genetic Adaptation to Variable Environments
Evolution of Seasonal Adaptations and Life History Traits in Chrysopa: Response to Diverse Selective Pressures
Modes of Reproduction
The Prophecies of Parthenogenesis
Competition and Adaptation among Diploid and Polyploid Clones of Unisexual Fishes
The Evolution of Life Span
Life History Variation in Dioecious Plant Populations: A Case Study of Chamaelirium luteum
Life History Variation Within Populations
The Measurement of the Direct and Indirect Intensities of Natural Selection
Phenotypic and Genetic Covariance Structure in Milkweed Bug Life History Traits
Life History Variation Among Populations
An Investigation of the Effects of Temperature on the Genetic Organization of Life History Indices in Three Populations of Drosophila melanogaster
Population Crosses and the Genetic Structure of Milkweed Bug Life Histories
Closing Discussion
Closing Discussion.