LOW-LEVELS OF IMMIGRATION BETWEEN CHAOTIC POPULATIONS CAN REDUCE SYSTEM EXTINCTIONS BY INDUCING ASYNCHRONOUS REGULAR CYCLES

Populations whose behaviour is described as chaotic commonly fall to very low values. Hence such populations have a high risk of extinction. However, recent research has shown that the probability of extinction for a system of linked populations is reduced when parameters are chosen such that the populations would behave chaotically in isolation. This effect is suggested to be the result of desynchronization between populations due to the amplification of external noise. Here, I investigate the effect on extinction risk of introducing weak coupling between chaotic populations in the absence of such external noise. Populations in the weakly linked system often do not behave chaotically even when parameter values are such that they would do so if isolated. Instead, they can exhibit simple cycles or remain at a stable level, sometimes with a reduced probability of falling to low population levels. More importantly, although subsets of the group of populations often follow the same dynamic pattern, all the populations never become synchronized, hence recolonization following extinction of a subset of the populations is a common occurrence.