On the Adaptive Value of Reproductive Synchrony as a Predator-Swamping Strategy

Abstract

The logic behind the hypothesis explaining reproductive synchrony as a strategy for reducing the predation of vulnerable offspring (predator swamping) is evaluated by means of two simple models. Predator swamping was found to be an adequate explanation for the occurrence of within-season reproductive synchrony when the predator exhibits a Holling type-II functional response (specialist predator). However, in the case of a generalist predator switching from alternative prey (Holling type-III functional response), which is expected to be a common functional-response type when particular prey are unavailable at certain times of the year, highly asynchronous reproduction may be the best reproductive strategy. In particular, when prey switching occurs at high offspring densities and/or the satiation density of the predator is high relative to the total reproduction of the prey population, the peak predation rate is expected to occur when reproduction is completely synchronous. Spatially clumped prey populations are expected to experience a dramatically increased predation rate if reproduction is synchronized within clumps but not between them. Hence, it is predicted that mechanisms promoting within-group reproductive synchrony are even less likely to have evolved as a predator-swamping strategy in patchily distributed populations, in which reproduction cannot be synchronized between groups. It is argued that the present models also may serve as a theoretical framework for studies on the evolution of fruiting synchrony in animal-dispersed plants.