A demographic, spatially explicit patch occupancy model of metapopulation dynamics and persistence

Abstract

Abstract. Patch occupancy models are extremely important and popular tools for understanding the dynamics, and predicting the persistence, of spatially structured populations. Typically this endeavor is facilitated either by models from classic metapopulation theory focused on spatially explicit, dispersal-driven colonization-extinction dynamics and generally assuming perfect detection, or by more recent hierarchical site occupancy models 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 used for future projections. However, despite being arguably of equal importance, dispersal and connectivity, local demography, and imperfect detection are rarely modeled explicitly and simultaneously. Understanding the spatiotemporal occurrence patterns of spatially structured populations and making biologically realistic long-term predictions of persistence would benefit from the simultaneous treatment of space, demography, and detectability. We integrated these key ideas in a tractable and intuitive way to develop a demographic and spatially realistic patch occupancy model that incorporates components of dispersal, local demographic stage-structure, and detectability. By explicitly relating stage-specific abundances to measurable patch properties, biologically realistic projections of long-term metapopulation dynamics could be made. We applied our model to data from a naturally fragmented population of water voles Arvicola amphibius to describe observed patch occupancy dynamics and to investigate long-term persistence under scenarios of elevated stage-specific local extinction. Accounting for biases induced by imperfect detection, we were able to estimate: stable, and higher than observed metapopulation occupancy; high rates of patch turnover and stage-specific colonization and extinction rates ( juvenile and adult, respectively); and juvenile dispersal distances (average 2.10 km). We found that metapopulation persistence in the presence of elevated extinction risk differed depending on which life stage was exposed, and was more sensitive to elevated juvenile rather than adult extinction risk. Predictions of persistence when dynamics are stage-specific suggest that metapopulations may be more resilient to changes in the environment than predicted when relationships are based on patch size approximations rather than population sizes. Our approach allows explicit consideration of local dynamics and dispersal in spatially structured and stage-structured populations, provides a more detailed mechanistic understanding of metapopulation functioning, and can be used to investigate future extinction risk under biologically meaningful scenarios.

Integrating demography, dispersal and interspecific interactions into bird distribution models

“…These models have similarities to DRMs in that they are estimated in a hierarchical framework, allow disentangling the different factors determining range dynamics, and account for imperfect detection through an observer model (Guillera‐Arroita ). Also, attempts have been made to incorporate different life stages (Sutherland et al ), and they have been successfully applied in climate impact analyses (Jones et al ). In the future, their ability to adequately predict temporal dynamics following climate change should be compared to other range dynamic approaches (Zurell et al ).…”

Increasing connectivity between metapopulation ecology and landscape ecology

“…In addition to the future avenues of research mentioned already, another potential extension of our work would be to make use of an abundance-based and/or stage-structured formulation (Sutherland et al 2014). In particular, our modeling framework provides a way to explicitly estimate matrix effects on connectivity and metapopulation colonization dynamics using empirical data.…”

Validating dispersal distances inferred from autoregressive occupancy models with genetic parentage assignments

“…The estimate of α for black rails (0.18 for IFM model‐averaged dispersal distance), a species in which colonization is strongly influenced by isolation, was similar to α for woodpeckers from a metapopulation in which isolation did not have a strong effect on colonization (α = 0.19; Robles & Ciudad, ). Furthermore, α for black rails was much lower than α for juvenile water voles despite strong effects of isolation on colonization (α = 0.33; Sutherland, Elston, & Lambin, ). Clearly, vagility alone does not determine the strength of the effect of isolation on colonization, which appears to be variable among taxa; some studies detected significant effects (Van Langevelde, ; Van Langevelde & Wynhoff, ; Wahlberg et al., ) while others detected weak or no effects (Pellet et al., ; Robles & Ciudad, ).…”