Temperature regimes shape similarity of life-history strategies between native and non-native freshwater fishes

Freshwater ecosystems are highly vulnerable to biological invasions, with increasing numbers of non-native fish species invoking severe ecological impacts. Life-history strategies reflect how fishes adapt to specific environments and play a critical role throughout the invasion process, leading to their application to understand large-scale patterns and drivers of freshwater fish invasions. Here, we compiled ecological traits for 14,679 freshwater fish species across 3,118 river basins worldwide to classify life-history strategies of native and non-native fishes and attempt to explain large-scale distributional patterns in diverse environments. We find that both native and non-native fishes are similarly shaped by environmental conditions (particularly temperature regimes) and exhibit consistent latitudinal gradients, with periodic strategists increasing and equilibrium and opportunistic strategists decreasing toward higher latitudes. Non-native fishes contain disproportionately more periodic and equilibrium strategists and fewer opportunistic strategists compared to native ones. Notably, the similarity of life-history strategies between native and non-native fishes is also primarily shaped by temperature regimes, increasing in colder or more seasonal environments but decreasing in warmer or more thermally stable ones. Overall, our results suggest that environmental filtering dominates in colder, more seasonal, high-latitude environments but weakens in warm, stable, low-latitude regions, where limiting similarity gains importance. This study provides new insights into how shifting environmental regimes shape global patterns in freshwater fish invasions and helps inform broad-scale conservation planning and management efforts.