Being first increases the probability of long diapause in rotifer resting eggs

Abstract

Monogonont rotifers typically undergo diapause to overpass adverse periods and often show within-population variation in diapause duration. Whether such variation corresponds to phenotypic plasticity, genetic polymorphism, or a bet-hedging strategy to cope with environmental unpredictability still remains unanswered. While bet hedging in diapause duration is often invoked in the rotifer literature, empirical evidence is scant and the description of a proximate mechanism responsible of the within-genotype variation required for bet hedging is still pending. We experimentally explored the role of maternal effects as responsible for the variability observed in the timing of resting egg hatching. By tracking the offspring of controlled crosses in clonal lineages of Brachionus plicatilis, we tested for differences in resting egg diapause duration due to (1) clone effect (controlling for genetic variability), (2) mother effect within clones, and (3) mother age and laying order (as candidate proximate factors explaining variability). We found a significant effect of laying order: the first eggs produced exhibited longer diapauses than eggs produced later. Finally, we critically discussed the idea that if rotifer mothers within a clone cannot anticipate the environment their offspring will experience, then they may produce resting eggs that vary in their timing of hatching via this maternal effect.