title: Within-and among-year germination in Sonoran Desert winter annuals: bet hedging and predictive germination in a variable environment.
abstract: In variable environments, organisms must have strategies to ensure fitness as conditions change. For plants, germination can time emergence with favourable conditions for later growth and reproduction (predictive germination), spread the risk of unfavourable conditions (bet hedging) or both (integrated strategies). Here we explored the adaptive value of within- and among-year germination timing for 12 species of Sonoran Desert winter annual plants. We parameterised models with long-term demographic data to predict optimal germination fractions and compared them to observed germination. At both temporal scales we found that bet hedging is beneficial and that predicted optimal strategies corresponded well with observed germination. We also found substantial fitness benefits to varying germination timing, suggesting some degree of predictive germination in nature. However, predictive germination was imperfect, calling for some degree of bet hedging. Together, our results suggest that desert winter annuals have integrated strategies combining both predictive plasticity and bet hedging.
authors: Department of Evolution and Ecology, University of California, Davis, CA, 95616, USA. jrgremer@ucdavis.edu.
authors: Jennifer R
authors: JR
authors: Gremer
authors: Center for Environmental Biology, University of California, Irvine, CA, 92697, USA.
authors: Sarah
authors: S
authors: Kimball
authors: Department Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA.
authors: D Lawrence
authors: DL
authors: Venable
mesh_terms: D005075:Biological Evolution; D003889:Desert Climate; D017753:Ecosystem; D018525:Germination / Q000502:physiology*; D008954:Models, Biological; D010944:Plants / Q000145:classification*; D012621:Seasons; D012639:Seeds / Q000502:physiology*
keywords: Bet hedging; density dependence; desert annuals; dormancy; evolutionarily stable strategies; integrated strategies; population dynamic models; predictive plasticity; seed bank; within-year germination