CLUTCH SIZE, OFFSPRING PERFORMANCE, AND INTERGENERATIONAL FITNESS

It is now generally recognized that clutch size affects more than offs pring number. In particular, clutch size affects a suite of traits ass ociated with offspring reproductive performance. Optimal clutch size i s therefore determined not by the numerically most productive clutch b ut by the clutch that maximizes collective offspring reproductive succ ess. Calculation of optimal clutch size thus requires a consideration of ecological factors operating during an intergenerational time frame , spanning the lifetime of the egg-laying adult and the lifetimes of h er offspring. The optimal clutch cannot define reproductive values in advance, but instead requires that the strategy chosen is the best res ponse to the set of reproductive values in that it itself generates. I n this article, we introduce methods for solving this problem, based o n an iterative solution of the equation characterizing expected lifeti me reproductive success. We begin by considering a semelparous organis m, in which case lifetime reproductive success is a function only of t he state of the organism. For an iteroparous organism, lifetime reprod uctive success depends upon both state and time, so that our methods e xtend the usual stochastic dynamic programming approach to the evaluat ion of lifetime reproductive success. The methods are intuitive and ea sily used. We consider both semelparous and iterparous organisms, stab le and varying environments, and describe how our methods can be emplo yed empirically.