Natal dispersal and senescence

^*Institut des Sciences de L’Evolution, Université de Montpellier II, Place Eugène Bataillon, 34095 Montpellier Cedex 5 France; and ^†Laboratoire d’Ecologie, Université Pierre et Marie Curie et Ecole Normale Supérieure, Bâtiment A, Case 237, 7 quai Saint Bernard, 75252 Paris Cedex 05 France

Edited by Robert M. May, University of Oxford, Oxford, United Kingdom, and approved October 28, 1997 (received for review June 23, 1997)

Abstract

The potential existence of natal dispersal strategies depending on parental age has been suggested by Hamilton and May [Hamilton, W. D. & May, R. M. (1977) Nature 269, 578–581] for organisms whose survival rates decline with age. When competition between parent and offspring is strong, any individual should disperse a smaller fraction of its offspring when it ages. Here, we verify their verbal prediction. First, we determine the evolutionarily stable dispersal strategy conditional on parental age, associated with a particular senescence curve. We show that such a conditional dispersal strategy should evolve independently from the genotype controlling the offspring dispersal behavior. Second, studying a population of common lizards, we provide empirical evidence of a relation between dispersal of female offspring and maternal senescence, in agreement with our theoretical predictions.