科研之友
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摘要
Across a range of organisms, life-history transitions can be triggered by specific levels of seasonal cues, such as day length or temperature. This acts to regulate the life cycle relative to seasonal fluctuations, so that, for example, reproduction occurs when resources are most abundant. At an environmentally optimal cue level, individuals might be selected to respond in a similar way, and consequently abruptly increase population density through, for example, the production of offspring. However, if density dependence is operating, crowding will reduce individual fitness, and selection will then favour life-history transitions at different cue levels. We explore the eco-evolutionary dynamics that result from the interaction between density dependence and phenology using a life-history model of an annual plant and focus on the timing of seed germination within the year. We characterize the adaptive dynamics of the mean and variance across the year of germination timing. Our results indicate that, even in predictably varying environments, mean timing of germination is not evolutionarily stable, but may experience evolutionary branching if variance in germination timing is sufficiently constrained. Unpredictably varying environments extend contexts where this is the case.Synthesis. Even if there is a restricted time period in the year during which environmental conditions are most appropriate for germination, observed timing of germination might be very diverse. Density dependence selects for persistence of traits conferring variance in timing across the year and additionally can lead to evolutionary branching of mean germination timing, resulting in multiple coexisting genotypes corresponding to different mean germination timings.
- 出版日期2015-7
