Maternal effects in Daphnia: what mothers are telling their offspring and do they listen?

Maternal effects can significantly impact offspring performance. Provisioni ng of offspring with energy stores can quantitatively alter their growth ra tes, survivorship, and future fecundity, and influence population regulator y mechanisms. In this payer, we show that maternal effects can also qualita tively affect offspring reproduction (i.e. their mode of reproduction). The freshwater herbivore Daphnia pulex can change the amount of energy allocat ed between asexual and ephippial egg production Our experiments on individu als, experiencing "step-up" or "step-down" food manipulations, reveal that offspring qualitatively shift their energy allocation away from asexual rep roduction to ephippial egg production when there is a simple mismatch betwe en maternal and offspring food environments. We show that the response is a symmetric with respect to changes in food level, ephippial egg production i s higher with a greater mismatch between environments, and that the effect can be observed in dynamic experimental populations. These results point to a "generational memory" that could challenge our interpretation of field p atterns and mechanisms influencing population dynamics in Daphnia-algal sys tems.