Evolution shapes ecosystem resilience through spatial self-organization.

Abstract

Drylands are globally widespread and ecologically important but vulnerable to climate change. Many exhibit spatially self-organized vegetation patterns that enhance resilience by enabling vegetation to reorganize their patterns under drying, thereby optimizing water use and maintaining productivity. Plants can also undergo evolution in response to environmental change. Although both spatial self-organization and rapid evolution are fundamental mechanisms of resilience, their interaction remains largely unknown. Using a theoretical model, we examine how these mechanisms interact to shape vegetation transitions-abrupt or gradual-and ecosystem resilience under climatic drying. We find that pattern formation can suppress adaptation by maintaining soil moisture beneath vegetation patches despite rainfall decline, thereby limiting selection for increased drought tolerance. However, this suppression is largely alleviated under the variable rainfall typical of drylands. In turn, evolution feeds back on self-organization by increasing the spatial plasticity of vegetation patterns and their ability to reorganize under changing climate, although this positive effect weakens as evolutionary rate increases. Considering direct (adaptation) and indirect (pattern-mediated) effects, evolution enhances resilience, with indirect effects via pattern plasticity dominating. Within model scenarios spanning plausible rainfall variability and relative evolutionary-to-ecological rates, more than half of vegetation transitions are abrupt involving biomass losses exceeding 50%, highlighting a potential mechanism underlying recent global observations of widespread abrupt vegetation losses in drylands. These results demonstrate that evolution and spatial self-organization jointly determine dryland resilience under environmental change and highlight the unexpected role of evolution in patterned landscapes, calling for integrative approaches to predict ecosystem responses in a changing world.