干旱区生态环境知识资源中心

Genotypes that hedge their bets can be favored by selection in an unpredictably varying environment. Bet hedging can be achieved by systematically expressing several phenotypes, such as one that readily attempts to reproduce and one that procrastinates in a dormant stage. But how much of each phenotype should a genotype express? Theory predicts that evolving bet-hedging strategies depend on local environmental variation, on how the population is regulated, and on exchanges with neighboring populations. Empirically, however, it remains unknown whether bet hedging can evolve to cope with the ecological conditions experienced by populations. Here we study the evolution of bet-hedging dormancy frequencies in two neighboring populations of the chestnut weevil, Curculio elephas. We estimate the temporal distribution of demographic parameters together with the form of the relationship between fecundity and population density and use both to parameterize models that predict the bet-hedging dormancy frequency expected to evolve in each population. Strikingly, the observed dormancy frequencies closely match predictions in their respective localities. We also found that dormancy frequencies vary randomly across generations, likely due to environmental perturbations of the underlying physiological mechanism. Using a model that includes these constraints, we predict the whole distribution of dormancy frequencies whose mean and shape agree with our observed data. Overall, our results suggest that dormancy frequencies have evolved according to local ecological conditions and physiological constraints.