Optimal apostatic selection: how should predators adjust to variation in prey frequencies?

Although frequency-dependent predation or apostatic selection has been established as one of the phenomena that may promote prey diversity, little is known about its selection. We studied such selection with a model with two prey types, treating frequency-dependent predator behaviour as an evolving trait determined by two parameters. One parameter controlled change in both prey type detection probabilities as a consequence of detecting a prey individual of a given type, and the other controlled the maximal amount of bias in detection probabilities of the two prey types. We let frequency-dependent behaviour evolve under different conditions of prey frequency variation. We found that frequency-dependent predator behaviour was most beneficial when deviations from equal prey type frequencies were large. Furthermore, different patterns of prey type variation selected for different types of frequency-dependent predator behaviour. We conclude that optimal frequency-dependent predator behaviour is likely to vary with ecological conditions.