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 of the University of Iowa and held in Iowa City on October 13 and 14, 1980. Prompted by a recent 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 closer 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 well 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."

This volume is based on a workshop on "Population Biology of. Plants The Interfaces (Genetics, Physiology, Demography, Biogeography)," with a specific profile on "Diversification of Plant Populations in relation to Modes of Reproduction and Dispersal Genetic and Physiological Mechanisms," held in Port-Camargue, France, from May 21-25, 1984. This workshop was initiated by the "Unit of Population and Community Biology," in Montpellier, and sponsored by the NATO Scientific Affairs Division (ARW grant 876/83) and by the CNRS (Table ronde). All populations are subjected to environmental "screening." Given a genetic diversity whose expression can be modified by a degree of demographic and individual plastici ty (at the morphological and physiological levels), they present a structure related to their environment. Ideally populations should be studied simultaneously from the point of view of the population geneticist, the physiologist and the demographer . These specific approaches only become fully meaning full in the "light of Evolution." Among the evolutionary forces that quantitatively act on the frequencies, objects of interest of workers specialising in Population Biology are selection and drift. An other main object of the study must be dispersal. But, its playing extent - relative to the other forces - in the adjustment to the environment is not fully recognized.