Environmental variability modulates trait matching, indirect effects, and resilience in adaptive mutualistic networks

Environmental variability is ubiquitous, yet how its magnitude, temporal autocorrelation, and synchrony across species shape the stability and trajectories of eco-evolutionary dynamics in adaptive ecological networks remain poorly understood. Here, we develop an adaptive mutualistic network model to examine how different features of environmental variability, together with ecologically mediated indirect effects, jointly shape network resilience and patterns of trait matching. Environmental variability generally reduces network resilience while increasing both trait mismatching and trait heterogeneity. Indirect effects enhance resilience and promote tighter trait matching both among interacting species and between species and their environment by stabilising abundance dynamics and indirectly constraining selection pressures. These effects depend on network position: peripheral species experience stronger indirect effects, leading to tighter between-species trait matching but weaker alignment with environmental optima, whereas core species experience weaker indirect effects, reduced interspecific trait matching, but stronger alignment between species traits and environmental optima. Increasing temporal autocorrelation and greater variability amplitude further erode resilience and trait matching by amplifying persistent environmental mismatches and suppressing indirect stabilising pathways, whereas higher cross-species synchrony buffers mutualistic networks by maintaining indirect effects. Together, our results demonstrate that environmental variability reshapes eco-evolutionary dynamics not only through direct environmental forcing, but also by modulating indirect interaction pathways embedded in network structure, highlighting the joint roles of indirect effects, topology, and trait matching in determining adaptive mutualistic network stability.