The Imbalance of Nature: The Role of Species Environmental Responses for Community Stability

Understanding stability is crucial for predicting ecological responses to environmental fluctuations. While the diversity-stability relationship is well studied, the role of species' fundamental responses remains underexplored. We investigate how the distribution of species' fundamental responses, captured by a novel metric—imbalance—drives community stability through asynchrony and population stability. Using a protist microcosm experiment, we manipulated species richness and response distributions (defined as interspecific variation in species performance curves) under fluctuating temperature at different nutrient concentrations. Results show that lower imbalance leads to higher temporal stability, while richness has no effect. Structural equation modelling revealed that asynchrony and population stability explain 90% of the variation in stability. Imbalance estimated from monocultures predicted community stability, suggesting that fundamental species responses drove community stability. This study offers new insights into the responses of ecological systems to environmental change.