Scaling of population resilience with dispersal length and habitat size

Abstract

Environmental fluctuations can create population-depleted areas and even extinct areas for the population. This effect is more severe in the presence of the Allee effect (decreasing growth rate at low population densities). Dispersal inside the habitat provides a rescue effect on population-depleted areas, enhancing the population resilience to environmental fluctuations. Habitat reduction decreases the effectiveness of the dispersal rescue mechanism. We report here how the population resilience to environmental fluctuations decreases when the dispersal length or the habitat size are reduced. The resilience reduction is characterized by a decrease of the extinction threshold for environmental fluctuations. The extinction threshold is shown to scale with the ratio between the dispersal length and the scale of environmental synchrony, i.e. it is the dispersal connection between non-environmentally-correlated regions that provides resilience to environmental fluctuations. Habitat reduction also decreases the resilience to environmental fluctuations, when the habitat size is similar to or smaller than the characteristic dispersal distances. The power laws of these scaling behaviors are characterized here. Alternative scaling functions with spatial scales of population synchrony are found to fit the simulations worse. These results support the dispersal length as the critical scale for extinction induced by habitat reduction.

Specialization into Host Sea Anemones Impacted Clownfish Demographic Responses to Pleistocene Sea Level Changes

“…abitat loss and fragmentation pose significant threats to species biodiversity and population resilience across ecosystems, disrupting natural habitats and connectivity essential for species persistence [1]. While habitat loss negatively affects species biodiversity and population resilience [2,3], habitat fragmentation effects are more complex and context-dependent [4,5]. Habitat fragmentation can promote allopatric speciation and trigger diversification processes [6,7], while limiting gene flow between previously connected populations, leading to loss of genetic diversity and compromised resilience of populations [8,9].…”