On the evolution of reproductive rates in populations with equilibrium and cyclic densities

A mathematical model for studying the evolution of optimal life histories is presented. This model explicitly incorporates the population dynamics of the organism under evolution. Reproductive strategies in cyclic (or opportunistic) and stable (or equilibrium) populations are compared. A continuum of different kinds of population dynamics patterns may be obtained, the extremes of which are the opportunistic and equilibrium strategies (or species). Our analysis further predicts that more resources should be devoted to reproduction than to competitive abilities in an opportunistic species. For equilibrium species, the allocation priorities should be reversed. Predictions from the theory are compared with data on small rodent species exhibiting regular density variations.