Sudden, sustained local extinction synchronizes adjacent populations in experimental population networks
Spatially segregated populations of the same species tend to vary in abundance with some degree of synchrony. Understanding factors that affect synchrony is important because highly synchronized populations are predicted to have lower persistence than weakly synchronized populations. For dispersive species, previous research has suggested that sudden, sustained local (i.e., population-level) extinction may synchronize the dynamics of extant populations within dispersal distance of the extinct population. Because this hypothesis has not been tested in replicated living systems, we developed protozoan population networks and used them to test the effect of local extinction on network synchrony. We also evaluated changes in synchronized decline, network stability, and minimum mean population density because these variables are associated with synchrony and network-wide extinction risk.
Although there was no effect of local extinction on synchrony at the network level, the populations closest to the population subjected to extinction had elevated synchrony throughout the extinction period. The same pair had more periods in synchronized decline and a lower minimum mean density compared to the equivalent pair in control networks. These results support the hypothesis that sudden, sustained local extinction has the potential to increase the extinction risk of spatial population networks not only through reduced patch occupancy but also by synchronizing dynamics of remaining populations.