The relative importance of local and regional processes to metapopulation dynamics

Abstract

Metapopulation dynamics – patch occupancy, colonization and extinction – are the result of complex processes at both local (e.g. environmental conditions) and regional (e.g. spatial arrangement of habitat patches) scales. A large body of work has focused on habitat patch area and connectivity (area‐isolation paradigm). However, these approaches often do not incorporate local environmental conditions or fully address how the spatial arrangement of habitat patches (and resulting connectivity) can influence metapopulation dynamics. Here, we utilize long‐term data on a classic metapopulation system – the Glanville fritillary butterfly occupying a set of dry meadows and pastures in the Åland islands – to investigate the relative roles of local environmental conditions, geographic space and connectivity in capturing patch occupancy, colonization and extinction. We defined connectivity using traditional measures as well as graph‐theoretic measures of centrality. Using boosted regression tree models, we find roughly comparable model performance among models trained on environmental conditions, geographic space or patch centrality. In models containing all of the covariates, we find strong and consistent evidence for the roles of resource abundance, longitude and centrality (i.e. connectivity) in predicting habitat patch occupancy and colonization, while patch centrality (connectivity) was relatively unimportant for predicting extinction. Relative variable importance did not change when geographic coordinates were not considered and models underwent spatially stratified cross‐validation. Together, this suggests that the combination of regional‐scale connectivity measures and local‐scale environmental conditions is important for predicting metapopulation dynamics and that a stronger integration of ideas from network theory may provide insight into metapopulation processes.

The effect of summer drought on the predictability of local extinctions in a butterfly metapopulation

“…Survey data have been used to demonstrate that the long‐term persistence and population dynamics (local extinctions and recolonizations) of the metapopulation largely depend on the number of available habitat patches, their area, and their spatial configuration (i.e., connectivity) (Hanski & Ovaskainen 2000; Dallas et al. 2019). Other key factors affecting local extinctions and population dynamics are habitat quality (e.g., number of host plants) (Harrison et al.…”

“…Despite increasing year-to-year fluctuations (Hanski & Meyke 2005;Tack et al 2015), the overall size of the metapopulation has remained relatively stable; about 20% of available habitat patches are occupied each year. Survey data have been used to demonstrate that the long-term persistence and population dynamics (local extinctions and recolonizations) of the metapopulation largely depend on the number of available habitat patches, their area, and their spatial configuration (i.e., connectivity) (Hanski & Ovaskainen 2000;Dallas et al 2019). Other key factors affecting local extinctions and population dynamics are habitat quality (e.g., number of host plants) (Harrison et al 2011;Schulz et al 2019) and genetic characteristics of individuals (Saccheri et al 1998;Niitepõld & Saastamoinen 2017).…”

Spatial structure and dispersal dynamics in a house sparrow metapopulation

“…Dispersal in this house sparrow metapopulation strongly depends upon geographical isolation and habitat characteristics interacting with spatial variation in population size and temporal variation in individual recruit production. This study emphasises the need for analyses addressing how spatial features of the environment affecting variation in emigration and immigration interact with the factors affecting temporal fluctuations in local population dynamics in order to predict the persistence capacity of metapopulations (Hanski & Ovaskainen 2000;Dallas et al 2020;Dallas, Saastamoinen & Ovaskainen 2021).…”

Local connections and the larval competency strongly influence marine metapopulation persistence

“…Identifying node‐level metrics that strongly influence metapopulation persistence, provides opportunities to more directly investigate the influence of life histories and location on persistence (Dallas et al 2019). Network structure and node metrics were influenced by species‐specific differences, associated with species‐specific life history traits, and were mostly evident for in‐degree and out‐degree results.…”