THE MATERNAL EFFECT OF ANTI-PREDATOR BEHAVIOURAL AND MORPHOLOGICAL RESPONSES TO ASPLANCHNA IN BRACHIONUS CALYCIFLORUS

Predation is vital in regulating population and community structure in aquatic ecosystems. When predators exist, many organisms can reduce the risk of predation by generating specific anti-predator responses. Therefore, one pivotal goal in ecology is to investigate how prey respond to particular predators, and how prey pass the predator stress on to offspring. In Monogononta, Phylum Rotifera, when coexisting with predators, some rotifers are able to exhibit morphological, behavioural or life-history responses. And rotifer individuals without direct predator experience can exhibit morphological anti-predator defences via maternal effects. But no study has so far investigated if the behavioural anti-predator response could be triggered via maternal effect. Hence, in this study, we used B. calyciflorus as the model organism to investigate whether its floating behavioural response could be triggered through maternal effect. We hypothesized that B. calyciflorus individuals with maternal predator experience could express stronger floating behaviour when exposed to the predator. In the experiments, we independently investigated the effect of exposure time (2h and 18h) and oocyte status (with and without eggs) of B. calyciflorus on the floating behaviour or morphology of their offspring when re-expose the offspring to predator kairomone. Our results suggested that (1) when expose to Asplanchna predator kairomone, the rotifer offspring with maternal long time exposure experience (18h exposure) have higher proportion floating to the water surface than individuals without maternal experience; (2) the intensity of anti-predator morphological and behavioural responses depends on the maternal exposure time when the mother generation exposed to predator kairomone for longer time, the offspring would exhibit both stronger morphological and behavioural responses. Our results provide novel evidence that behavioural anti-predator response could be affected by maternal effect.