Cross-Continental Differences in Climate Asymmetrically Shape Temporal Ecological Processes in Riverine Insect...

Climatic fluctuations can play a crucial role in shaping large-scale patterns of biodiversity and biogeography. This study examines how climatic gradients and their variability influence family-level temporal ecological processes that govern the balance between stochastic and deterministic processes that underlie community dynamics of riverine insects. This comparison, done across multiple continents but mostly in the Northern Hemisphere, used long-term data from 302 sites mainly in Europe, ranging from 10 to 37 years, and with 4751 observations of family-level riverine insect assemblages. We analyzed spatial patterns in family richness, family-level temporal beta diversity, and associated ecological processes. Generalized additive models revealed high spatial heterogeneity, with family-level richness declining with latitude, but total family-level temporal beta-diversity decreasing with increasing latitude and elevation across the continents studied. The cross-continental results from generalized additive and dissimilarity models further showed spatial shifts in the proxy indicators of ecological processes (e.g., environmental variables and time-series decomposition), with stochastic processes (e.g., ecological drift) increasing in importance towards higher latitudes. In contrast, deterministic processes (e.g., temperature) declined. At a cross-continental perspective, these findings highlight how spatial asymmetry under fluctuating climates may shape riverine insect community dynamics and improve adaptive conservation strategies.