Maternal control of spontaneous dormancy termination in Daphnia pulex
This study examined maternal influence and life-history consequences of diapause termination timing in Daphnia pulex. We raised clonal isolates of D. pulex in mesocosms and observed hatching rates prior to and after exposing embryos to a cold shock. A substantial proportion of individuals hatched early, prior to the cold shock. We found that siblings from the same ephippium were more likely than expected by chance to emerge at the same time, even after dissection and separation, suggesting the presence of a maternal effect that influences diapause duration. We also found that for individuals who emerged early, the time to first reproduction was significantly delayed, and individuals produced fewer resting embryos in subsequent generations. We suggest that early diapause termination may be driven by maternal effects to generate offspring that emerge from dormancy at different times.