A NOTE ON THE TIMING OF TRADEOFFS IN DISCRETE LIFE-HISTORY MODELS

We discuss the timing of tradeoffs in discrete life history models. Wi th a simple mathematical example we show that different assumptions ab out the temporal order of costs and benefits resulting from a reproduc tive effort can lead to qualitatively different predictions. We examin e two models taken from the literature, in which an implicit assumptio n is that benefits from reproductive efforts are received before the c orresponding costs are paid. We show that the reverse assumptions woul d have led to very different results. Since there is no biological bas is for a bias towards a particular set of assumptions, we conclude tha t a more flexible approach should be used when studying optimality pro blems that are based on discrete life histories.