Aim To clarify the characteristics and contribution of oceanic dispersal (OD), a representative of long‐distance dispersal, to phylogenetic diversification on insular systems. Location Eastern Eurasia. Time Period Post‐Neogene. Major Taxa Studied Freshwater snails of the genus Gyraulus (Mollusca: Gastropoda). Methods We conducted comprehensive sampling across the entire distribution range of G. chinensis group, including sever...