The Evolution of Bet Hedging in Response to Local Ecological Conditions

Abstract

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.

Evolution of alternative insect life histories in stochastic seasonal environments

“…2008; Rajon et al. 2014). Bet‐hedging is also reflected in the predicted clinal variation in life histories (aim 3).…”

“…This is implied by the general tendency of a high predicted dormancy frequency in density‐dependent models compared to density‐independent ones (Bulmer 1984; Ellner 1985; Rajon et al. 2014). However, the effect of density dependency on the current predictions needs to be rigorously analyzed, and future studies should address this issue.…”

Climate and rapid local adaptation as drivers of germination and seed bank dynamics of Alliaria petiolata (garlic mustard) in North America

“…Plants, as well as some fungi (Graham, Smith & Simons ) and insects (Rajon et al . ), use dormancy as a type of forecasting to deal with future conditions based on their evolutionary histories. Dormancy, and differences among species and populations, appears to evolve, as predicted by theory, in proportion to bad years encountered in any particular locale (Evans et al .…”

Behavioural plasticity induced by intraspecific competition in host orientation in a parasitoid

“…Genotypes responsible for the expression of these phenotypes should be at a disadvantage against genotypes that reduce temporal variation in fitness (Rajon et al, 2014). Genotypes responsible for the expression of these phenotypes should be at a disadvantage against genotypes that reduce temporal variation in fitness (Rajon et al, 2014).…”