title: Bet hedging in desert winter annual plants: optimal germination strategies in a variable environment.
abstract: In bet hedging, organisms sacrifice short-term success to reduce the long-term variance in success. Delayed germination is the classic example of bet hedging, in which a fraction of seeds remain dormant as a hedge against the risk of complete reproductive failure. Here, we investigate the adaptive nature of delayed germination as a bet hedging strategy using long-term demographic data on Sonoran Desert winter annual plants. Using stochastic population models, we estimate fitness as a function of delayed germination and identify evolutionarily stable strategies for 12 abundant species in the community. Results indicate that delayed germination meets the criteria as a bet hedging strategy for all species. Density-dependent models, but not density-independent ones, predicted optimal germination strategies that correspond remarkably well with observed patterns. By incorporating naturally occurring variation in seed and seedling dynamics, our results present a rigorous test of bet hedging theory within the relevant environmental context.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA.
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Gremer
authors.forename: D Lawrence
authors.initials: DL
authors.lastname: Venable
mesh_terms: D000220:Adaptation, Biological / Q000502:physiology*; D001130:Arizona; D005075:Biological Evolution; D003889:Desert Climate; D018525:Germination / Q000502:physiology*; D008954:Models, Biological; D018521:Plant Physiological Phenomena; D011156:Population Density; D011157:Population Dynamics; D012639:Seeds / Q000502:physiology; D013045:Species Specificity; D013997:Time Factors
keywords: Bet hedging; delayed germination; density dependence; desert annuals; evolutionarily stable strategies; population dynamic models; seed bank