Introduction timing of genetic diversity in eco-evolutionary dynamics

Background/Question/Methods

Rapid contemporary evolution of prey defense can affect ecological dynamics, and in turn ecological dynamics gives feedback to evolution (eco-evolutionary dynamics). In microcosm experiments with plankton, previous studies have shown changes in frequencies of undefended and defended genotypes of prey species alter the oscillation phase-lag between predator and prey densities from an ordinary quarter-period to a half-period. The antiphase cycles are called "evolutionary cycles" and regarded as evidence of rapid evolution. We theoretically investigated how introduction timing of genetic diversity affects eco-evolutionary dynamics, especially focusing on evolutionary antiphase cycles.

Results/Conclusions

We found various bistabilities in a predator-prey model with type II functional response. Here we show that, because of the bistability, rapid evolution does not always result in antiphase cycles depending on initial conditions. In such a case, the phase-lag is a quarter-period and the contribution of prey evolution to predator dynamics is very small compared to that of prey abundance, in spite of rapidly evolving prey defense. When the initial system has only undefended prey and predator, we found that the introduction timing of the defended genotype can determine the fate of the system. We also demonstrate that the initial density of the introduced defended genotype affects the phase-lag between predator and prey. We discuss the relevance of our results to stochasticity and determinism of community assembly and eco-evolutionary dynamics.