Publication Date

November 2014

Journal or Book Title



Patch occupancy models are extremely important and popular tools forunderstanding the dynamics, and predicting the persistence, of spatially structuredpopulations. Typically this endeavor is facilitated either by models from classic metapopulationtheory focused on spatially explicit, dispersal-driven colonization–extinction dynamicsand generally assuming perfect detection, or by more recent hierarchical site occupancymodels that account for imperfect detection but rarely include spatial effects, such as dispersal,explicitly. Neither approach explicitly considers local demographics in a way that can be usedfor future projections. However, despite being arguably of equal importance, dispersal andconnectivity, local demography, and imperfect detection are rarely modeled explicitly andsimultaneously. Understanding the spatiotemporal occurrence patterns of spatially structuredpopulations and making biologically realistic long-term predictions of persistence wouldbenefit from the simultaneous treatment of space, demography, and detectability. Weintegrated these key ideas in a tractable and intuitive way to develop a demographic andspatially realistic patch occupancy model that incorporates components of dispersal, localdemographic stage-structure, and detectability. By explicitly relating stage-specific abundancesto measurable patch properties, biologically realistic projections of long-term metapopulationdynamics could be made. We applied our model to data from a naturally fragmentedpopulation of water voles Arvicola amphibius to describe observed patch occupancy dynamicsand to investigate long-term persistence under scenarios of elevated stage-specific localextinction. Accounting for biases induced by imperfect detection, we were able to estimate:stable, and higher than observed metapopulation occupancy; high rates of patch turnover andstage-specific colonization and extinction rates ( juvenile and adult, respectively); and juveniledispersal distances (average 2.10 km). We found that metapopulation persistence in thepresence of elevated extinction risk differed depending on which life stage was exposed, andwas more sensitive to elevated juvenile rather than adult extinction risk. Predictions ofpersistence when dynamics are stage-specific suggest that metapopulations may be moreresilient to changes in the environment than predicted when relationships are based on patchsize approximations rather than population sizes. Our approach allows explicit considerationof local dynamics and dispersal in spatially structured and stage-structured populations,provides a more detailed mechanistic understanding of metapopulation functioning, and canbe used to investigate future extinction risk under biologically meaningful scenarios.







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