OPTIMAL PATCH USE AND METAPOPULATION DYNAMICS

We compared the metapopulation dynamics of predator-prey systems with (1) adaptive global dispersal, (2) adaptive local dispersal, (3) fixed global dispersal and (4) fixed local dispersal by predators. Adaptive dispersal was modelled using the marginal value theorem, such that pr edators departed patches when the instantaneous rate of prey capture w as less than the long-term rate of prey capture averaged over all patc hes, scaled to the movement time between patches. Adaptive dispersal t ended to stabilize metapopulation dynamics in a similar manner to conv entional fixed dispersal models, but the temporal dynamics of adaptive dispersal models were more unpredictable than the smooth oscillations of fixed dispersal models. Moreover, fixed and adaptive dispersal mod els responded differently to spatial variation in patch productivity a nd the degree of compartmentalization of the system. For both adaptive dispersal and fixed dispersal models, localized ('stepping-stone') di spersal was more strongly stabilizing than global ('island') dispersal . Variation among predators in the probability of dispersal in relatio n to local prey density had a strong stabilizing influence on both wit hin-patch and metapopulation dynamics. These results suggest that adap tive space use strategies by predators could have important implicatio ns for the dynamics of spatially heterogeneous trophic systems.