Synchrony and stability: opposing effects of dispersal in host-enemy metapopulations?

Background/Question/Methods   Models of host-enemy interactions are prone to instability, so a rich body of theory has developed around possible stabilizing mechanisms to explain the persistence of natural host-enemy communities. One such mechanism is dispersal among spatially distinct populations, but there is a general consensus that in order for dispersal to enhance stability, populations must remain asynchronous. The effect of dispersal on synchrony is itself an extremely well-studied topic. Interestingly, though, the broader question of how dispersal impacts spatiotemporal population dynamics has resisted synthesis because dispersal can induce both synchrony and stability, the latter of which is inhibited by the former. Using analytical results from a simple model and simulation results from more realistic host-enemy models, I characterize and discuss the mechanistic relationship between these two widely cited consequences of dispersal: regional synchrony and local population stability.

Results/Conclusions   My work shows that the synchrony-stability relationship is sometimes increasing and sometimes decreasing, but that the direction of the relationship is consistently determined by the underlying driver of synchrony. With some knowledge of the synchronizing influences (high dispersal, correlated stochasticity, etc) acting on a particular metapopulation, the total effect of dispersal, with its potential to influence both synchrony and stability, can be resolved.