Habitat patch arrangement and metapopulation persistence of predators and prey

This study tests whether spatial dynamics can stabilize metapopulations with a small number of patches and tests the influence of patch arrangement. I measured persistence of predator and prey protists in replicated microcosms with two to four patches. Predators persisted for 85-437 generations (26-130 d). As predicted by single-species and/or predator-prey metapopulation models, substantial variation in predator metapopulation persistence was accounted for by the amount of patches or habitat, number of dispersal corridors, maximum interpatch distance, and proportion of patches providing colonists (which depends on the explicit spatial arrangement of patches). Contrary to expectation, persistence was not influenced by loops of patches or patch similarity. Persistence was also shorter in four-patch loops than three-patch loops, indicating an interaction between patch number and arrangement, which is not predicted by published models. Spatial synchrony of density fluctuations was central to predator persistence but had complex effects on extinction-colonization dynamics, rescue effects, and predator-prey interaction strength. Levins's model, containing only extinction-colonization dynamics, predicted patch occupancy for prey but not predators. Predators did, however, show rescue effects and changes in interaction strength. This work illustrates the need to combine experimentation with modeling to understand the mechanisms of spatial dynamics.