Theoretical predictions of how the amount of genetic variation in prey populations alters predator-prey community dynamics

Background/Question/Methods

In this talk, I explore how the amount of standing genetic variation in prey populations alters the stability of predator-prey communities.  In the absence of evolution, predator-prey communities can exhibit stable or cyclic ecological dynamics.  Recent theoretical and experimental work has shown that rapid evolution of prey defense can alter the shapes of predator-prey cycles. In addition, when populations have large amounts of standing genetic variation (or high mutation rates), species evolution can stabilize cyclic systems or destabilize stable systems.  However it is not clear how much standing genetic variation is needed in order for stabilization/destabilization to occur.  Here, by analyzing a theoretical eco-evolutionary predator-prey model, I determine the biological conditions under which prey evolution stabilizes or destabilizes the ecological dynamics of the system, and I determine how those effect depend on the amount of standing genetic variation in the prey population.

Results/Conclusions

Using a theoretical eco-evolutionary predator-prey model, I categorize the conditions under which the evolution of prey defense stabilizes cyclic systems and induces cyclic dynamics in stable ecological systems.  Prey evolution destabilizes systems in two cases: one where faster rates of evolution destabilize the system and one where intermediate rates of evolution destabilize the system.  Prey evolution stabilizes systems in similar cases: one where faster rates of evolution stabilize the system and one where intermediate rates of evolution stabilize the system.  I discuss how the conditions defining these cases depend on the prey fitness gradient and the stabilities of the ecological and evolutionary subsystems.  In addition to yielding insight into how standing genetic variation influences ecological dynamics, this work also builds a connection between the theory of adaptive dynamics (a theory of slow evolutionary dynamics) and previous theoretical work on rapid evolution.  I discuss how phenomena predicted by both bodies of theory are related (e.g., evolutionary branching and eco-evolutionary cycles) and can be used to understand the community dynamics observed in natural systems.