Abandoning the ship using sex, dispersal or dormancy: multiple escape routes from challenging conditions

Natural populations often experience environments that vary across space and over time, leading to spatio-temporal variation of the fitness of a genotype. If local conditions are poor, organisms can disperse in space (physical movement) or time (dormancy, diapause). Facultatively sexual organisms can switch between asexual and sexual reproduction, and thus have a third option available to deal with maladaptedness: they can engage in sexual reproduction in unfavourable conditions (an 'abandon-ship' response). Sexual reproduction in facultatively sexual organisms is often coupled with dispersal and/or dormancy, while bet-hedging theory at first sight predicts sex, dispersal and dormancy to covary negatively, as they represent different escape mechanisms that could substitute for each other. Here we briefly review the observed links between sex, dormancy and dispersal, and model the expected covariation patterns of dispersal, dormancy and the reproductive mode in the context of local adaptation to spatio-temporally fluctuating environments. The correlations between sex, dormancy and dispersal evolve differently within species versus across species. Various risk-spreading strategies are not completely interchangeable, as each has dynamic consequences that can feed back into the profitability of others. Our results shed light on the discrepancy between previous theoretical predictions on covarying risk-spreading traits and help explain why sex often associates with other means of escaping unfavourable situations. This article is part of the theme issue 'Linking local adaptation with the evolution of sex differences'.