Geological processes shaping freshwater biodiversity: a synthesis of global evidence

Recent genomic data highlight the key roles of geological processes in shaping the diversification and biogeography of freshwater lineages. Specifically, physical processes such as tectonic uplift, erosion, glaciation, lake formation, and sea-level fluctuation contribute extensively to the evolution of biotic diversity within and among drainages. River capture events can simultaneously isolate and merge lineages, with isolation potentially leading to speciation, and secondary contact enhancing alpha diversity within merged river reaches. The increased speciation rates of newly isolated lineages may be countered by their reduced population sizes and increased extinction risks. Knowledge of drainage history is essential for explaining freshwater biodiversity patterns, and also for understanding the drivers and temporal scales of biological evolution. Future interdisciplinary genomic and geological analyses are needed to understand and conserve freshwater biodiversity in a fast-changing world.