Bet hedging via intermediate hatching fractions: demographic evidence from rotifer diapausing egg banks

Abstract In this study, we investigated how hatching fractions of diapausing eggs in rotifers are related to variation in reproductive success in different habitats. It is postulated that an intermediate hatching fraction may be a bet hedging strategy, an adaptation that reduces the risk of reproductive failure by prolonging diapause, which decreases success in favorable seasons but ensures survival in unfavorable ones. Through the analysis of age-structured egg banks from eight populations of the rotifer Brachionus plicatilis in Spain, we were able to estimate variation across time in reproductive success. In addition, we used data obtained in previous studies, in which diapausing eggs were isolated from the most recent sediment layer of the ponds inhabited by the studied rotifer populations and these eggs were subjected to hatching experiments under controlled laboratory conditions. We found that hatching fractions were lower in populations with greater variation in reproductive success, confirming the predictions of bet hedging. However, no significant relationship was found between variation in reproductive success and hydrological conditions, such as the predictability of alternating dry and wet periods. Therefore, it is still necessary to identify the specific environmental factors that generate time uncertainty in the reproductive success of these rotifers.