Long‐Term Replacement Cycles in Cladoceran Communities: A History of Predation

Populations of the waterflea Bosmina undergo temporal replacement cycles (seasonal successions of clones or closely—related sibling species) in many modern lakes, where long—featured winter clones are subsequently replaced by short—featured summer clones. Inspection of lake sediment reveals that populations have also undergone long—term replacements. Remarkably well—preserved remains, heavily biased towards summer morphology by production dynamics, document a progressive shift from late—glacial long—featured phenotypes to recent short—featured phenotypes. Several lines of evidence suggest that these long—term substitutions reflect a changing balance between planktivorous fishes and predatory copepods.