Bet-hedging germination of desert annuals: variation among populations and maternal effects in Lepidium lasiocarpum.
Prolonged seed dormancy in desert annuals has been modeled as a bet-hedging adaptation to environmental uncertainty. Several aspects of that theory were tested in the preceding article; further results using Lepidium lasiocarpum are reported here. Seeds from different populations of Lepidium differed in their germination behavior. These differences were weakly correlated with differences in the mean winter rainfall among the collection sites: as predicted, sites with greater mean precipitation had less dormancy. Precipitation in the year of seed production was a strong predictor of germination behavior: sites with greater precipitation produced seeds with more dormancy. In a second set of experiments, maternal plant size had a strong effect on germination: plants that produced many seeds had a smaller proportion germinate in the first year. While these results support the general theories of bet-hedging germination in desert annuals, they indicate that selection due to year-to-year variation in population size and sibling competition may be more important in the evolution of seed dormancy than previously thought.
Philippi
T
T