Dormant plasticity of rotifer diapausing eggs in relation to predator kairomones

In freshwater ecosystems, dormant strategy of diapausing eggs under predation risk has important ecological implication for zooplanktons. Although kairomones released by predators can induce phenotypic responses of prey, hatching patterns of diapausing eggs in relation to kairomones have received contradictory conclusions in zooplanktons. Maternal effects may also affect hatching strategy of diapausing eggs during predator-prey interactions. We used classical Brachionus calyciflorus–Asplanchna models to determine timing and proportion of diapausing-egg hatchlings in association with parental and embryonic exposure to kairomones. Results obtained from two Brachionus clones supported hypothesis that diapausing eggs could detect Asplanchna kairomones and adjusted hatching patterns. Diapausing eggs showed early and synchronous hatching patterns in environment with kairomones. Data also supported prediction that Brachionus mothers could transmit environmental cues of Asplanchna to diapausing eggs and affect their hatching in relation to kairomones. Compared with diapausing eggs from mothers not exposed to kairomones, diapausing eggs produced by mothers experienced kairomones attained higher hatching rate when they hatched in the same environment either with kairomones or not. Our results suggest that diapausing eggs of B. calyciflorus possess dormant plasticity to defend against predation from Asplanchna, which may be influenced by maternal effects during asexual or sexual life cycles.