Heterogeneity in patch quality buffers metapopulations against pathogen impacts

Background/Question/Methods

Many wildlife species persist as metapopulations on a network of ephemerally occupied habitat patches connected by dispersal. These dynamics may be intrinsic to the life history of a species, but can also be a consequence of habitat fragmentation and degradation from human activities. An appealing management tool for rescuing declining metapopulations is to improve the quality of remnant patches by increasing resource availability, yet prior studies show that supplemental feeding of wildlife can facilitate local transmission of virulent pathogens. Here we investigate the landscape-level consequences of resource provisioning for metapopulation persistence and pathogen spread, using a simple model that accounts for pathogen transmission between patches and for heterogeneity in patch quality arising from resource improvement.

Results/Conclusions

In the absence of disease, the fraction of patches occupied at equilibrium increases with the number of patches improved by resource provisioning. However, we show that equilibrium occupancy can actually decline when provisioning occurs at a large number of patches by facilitating invasion of virulent pathogens. This occurs because lower-quality, unprovisioned patches act as a ‘sink’ for the pathogen, and therefore equilibrium occupancy is maximized for mixtures of high- and low-quality patches. Our results suggest that patch heterogeneity may be an important mechanism for metapopulation persistence in the face of emerging pathogens, and also highlight the need for more empirical research on landscape-level consequences of local management practices to avoid amplifying pathogen impacts on imperiled hosts.