An empirical confirmation of diversified bet hedging as a survival strategy in unpredictably varying environments

Environmental change jeopardizes the survival of species from variable environments by making the occurrence of favorable conditions less predictable. For organisms with long-lived propagules (e.g., spores, eggs, or seeds), the theory of diversified bet hedging (DBH) predicts that delayed hatching over different growing seasons can help populations avoid extinction. Empirical observations in different organisms are consistent with DBH, but integrated tests that simultaneously validate the main theoretical assumptions and predictions are lacking. In this study, we combine field and multi-generational lab experiments to provide a complete test of DBH. Consistent with DBH predictions, resting egg clutches of the fairy shrimp Branchipodopsis wolfi, which inhabits rain-fed temporary rock pool environments with unpredictable inundations, hatched partially over a succession of inundations with identical hatching cues. Bet hedging was more common in populations from more unpredictable habitats where hatching fractions were lower. This differentiation in hatching strategies was preserved after two generations under common garden conditions, which implies intrinsic (epi-)genetic control of hatching. Finally, a demographic model confirmed that lower hatching fractions increase long-term population growth in unpredictable habitats. With this paper we propose a method to calculate probabilities of successful recruitment for organisms that use imperfect cues and show that this drives selection for variation in life history strategies as part of a DBH strategy.