Reproductive decision-making by female peacock wrasses: Flexible versus fixed behavioral rules in variable environments

Abstract

Because environments are temporally variable, animals may often estimate the current environmental state to inform their behavioral choices. However, using experience may cause behavior to lag behind the current state of the environment, and estimates may suffer from sampling errors. We used stochastic dynamic models to examine the environmental conditions that favor flexible rather than fixed estimates and behaviors. The examination was conducted in the context of reproductive decisions made by the female peacock wrasse (Symphodus tinca), a nearshore Mediterranean fish. Female peacock wrasses can choose to spawn in a nest, with males that defend these nests within territories, or out of a nest, with males that defend neither territories nor nests. A female must expend effort and time to find nesting males, and the profitability of this search, relative to spawning with nonnesting males, changes with the density of nests and relative hatching success of eggs in and out of nests. A female can increase her fitness by estimating the environment's state and matching her reproductive decisions to the current environment. These estimates can be flexible and formed by experience, or fixed and formed by selection. We found that flexible estimates based on experience do better when there is variance within and between seasons and when there is greater uncertainty. The optimal rate for forgetting experiences is set by the rate of environmental change. Comparisons of predicted female behavior using flexible and fixed estimates with observed behavior suggest that females use estimates that are updated by experience.