COS 310-5 - Landscape fragmentation overturns classical metapopulation thinking

Abstract: Landscape fragmentation represents a growing threat to global biodiversity. Existing theory suggests that the process will lead to a decline in metapopulation viability. However, since most metapopulation models are restricted to simple networks of discrete habitat patches, the effects of natural landscape fragmentation are largely unknown. To close this major gap in ecological theory, we developed a spatially explicit, individual-based model applicable to realistic landscape structures, bridging metapopulation ecology and landscape ecology. This model reproduced classical metapopulation dynamics under conventional model assumptions, but on naturally fragmented landscapes, it uncovered general dynamics that are in stark contradiction to the prevailing views in the ecological and conservation literature. Notably, in stochastic environments, natural fragmentation can give rise to a) diverging environmental effects on metapopulation persistence, b) seesaw-like community shifts, and c) both synchronization and desynchronization of local population dynamics. Furthermore, counter to common intuition, species that interact locally (“residents”) were often more resilient to fragmentation than long-ranging “migrants”. This set of findings signals an urgent need to fundamentally reconsider our approach to ecosystem management in a noisy and fragmented world.