Neglected consequences of spatio-temporal heterogeneity and dispersal: Metapopulations, the inflationary effect, and real-world consequences for public health

The metapopulation perspective is an important conceptual framework in ecology, biogeography, and evolutionary ecology. Metapopulations are spatially distributed populations linked by dispersal. Both metapopulation models and their community and ecosystem level analogues, metacommunity and meta-ecosystem models, tend to be more stable regionally than locally and display an enhancement in abundance because of the interplay of spatio-temporal heterogeneity and dispersal (an effect that has been called the "inflationary effect"). We highlight the essential role of spatio-temporal heterogeneity in metapopulation biology, sketch empirical demonstrations of the inflationary effect, and provide a mechanistic interpretation of how the inflationary effect arises and impacts population growth and abundance. The spread of infectious disease is used to illustrate how this effect, emerging from the interplay of spatiotemporal variability and dispersal, can have serious real-world consequences. Namely, failure to recognize the full possible effects of spatio-temporal heterogeneity likely enhanced the spread of COVID-19, and a comparable lack of understanding of emergent population processes at large scales may hamper the control and eradication of other infectious diseases. We finish by noting how the effects of spatio-temporal heterogeneity, including the inflationary effect, have implicitly played roles in many traditional themes in the history of ecology. The inflationary effect is implicit in processes explored in subdisciplines as far ranging as natural enemy-victim dynamics, species coexistence, and conservation biology. Seriously confronting the complexity of spatiotemporal heterogeneity has the potential to push many of these subdisciplines forward. ### Competing Interest Statement The authors have declared no competing interest.