Global assemblage stability is driven by asynchrony shaped by environmental heterogeneity

James Inman Cant , Anne E Magurran, Maria Dornelas

Evidence suggests the diversity-stability relationship relies on asynchrony among populations. Yet our limited understanding of how the mechanisms underlying stability and asynchrony manifest across ecological scales prevents reliable forecasts of ecological stability amid ongoing biodiversity change. Here, linking stability, asynchrony and species richness across plant, bird, mammal, amphibian, and fish assemblages worldwide, we unveil a U-shaped diversity-stability relationship, with population- and assemblage-level stability greatest at both low and high diversity. Across taxa, we illustrate how this relationship is predominantly realised through patterns in population asynchrony, which itself is enhanced in communities exposed to greater environmental heterogeneity but erased by human impacts. Together, these findings stress how anthropogenic pressure and losses of environmental heterogeneity jeopardise the asynchrony required for sustaining the stability of natural ecosystems worldwide.