Abstract

One of the merits of the r- and k-selection proposal was to make evident that in order to understand the joint evolution of the those constellations of traits that constitute life-histories, it is mandatory to attend the environmental dimensions capable to act as selective pressures on the referred traits. The theoretical tradition has considered separately the components of life histories. We tackle here, instead, the joint optimization of two energetic variable: reproductive effort (  ) and the energetic size (e) assigned to each offspring, traditionally optimized separately. We use two methods to consider simultaneously both variables. First, we optimize after introducing an important non-linearity, neglected so far, under the form of reproductive cost. Thereafter, the parameters are perturbed to observe their effects on the optimal pattern. Second, we couple the two optimizations by introducing density-dependence of juvenile survival, as a function of the offspring size. When considering density-dependent mortality risks, both avoidable and unavoidable, optimization requires searching a stable strategy in an evolutionary game. This work is a modified synthesis of previously published results and other unpublished, as well as of some aspects not included before