Thursday, August 7, 2008: 3:35 PM
104 B, Midwest Airlines Center
Background/Question/Methods
Masting by long-lived perennial plants is a synchronous and widespread reproductive event involving most individuals in a population and/or species in a community. Masting is associated with large inter-annual variation in reproductive effort and has been hypothesized to provide defense against seed predation. Some masting tree species are wind pollinated, but many are animal pollinated, and for the latter, intermittent mass flowering causes temporal fluctuation of resource availability for pollinators, which in turn may influence the flowering phenology of these plant species.
Results/Conclusions
In this paper, we present a mathematical model to shed light on the role of plant-pollinator interactions in shaping flowering phenology at a community level. A basic model for plant-pollinator interactions builds on the resource budget model. The assumptions of the model are: (1) plants accumulate resources by photosynthesis every day; (2) if stored resources exceed a threshold, plants set flowers using the excess resources above this threshold; (3) flowers are pollinated at a rate dependent on pollinator availability; and (4) pollination is proportional to fitness through seed set. The pollination rate is modeled to reflect the balance between facilitation and competition of pollination. Pollinators are often attracted to a given plant species only after a certain threshold density of flowers are in bloom. However, a heavy bloom may satiate pollinators and reduce the number of visits per flower. Plant species sharing pollinators may synchronize flowering if co-flowering contributes to pollinator attraction, or may segregate flowering if co-flowering results in a competition for pollination services. Thus, the direction and intensity of selection on phenology is determined by the balance between facilitation and competition of pollination within plant-pollinator networks. The model outputs show that as the cost of producing a single flower increases, and as pollination rate decreases with lower flowering intensity, flowering synchrony among plant species is more likely to evolve. We discuss these results in the context of coevolution of plant-pollinator interactions.
Masting by long-lived perennial plants is a synchronous and widespread reproductive event involving most individuals in a population and/or species in a community. Masting is associated with large inter-annual variation in reproductive effort and has been hypothesized to provide defense against seed predation. Some masting tree species are wind pollinated, but many are animal pollinated, and for the latter, intermittent mass flowering causes temporal fluctuation of resource availability for pollinators, which in turn may influence the flowering phenology of these plant species.
Results/Conclusions
In this paper, we present a mathematical model to shed light on the role of plant-pollinator interactions in shaping flowering phenology at a community level. A basic model for plant-pollinator interactions builds on the resource budget model. The assumptions of the model are: (1) plants accumulate resources by photosynthesis every day; (2) if stored resources exceed a threshold, plants set flowers using the excess resources above this threshold; (3) flowers are pollinated at a rate dependent on pollinator availability; and (4) pollination is proportional to fitness through seed set. The pollination rate is modeled to reflect the balance between facilitation and competition of pollination. Pollinators are often attracted to a given plant species only after a certain threshold density of flowers are in bloom. However, a heavy bloom may satiate pollinators and reduce the number of visits per flower. Plant species sharing pollinators may synchronize flowering if co-flowering contributes to pollinator attraction, or may segregate flowering if co-flowering results in a competition for pollination services. Thus, the direction and intensity of selection on phenology is determined by the balance between facilitation and competition of pollination within plant-pollinator networks. The model outputs show that as the cost of producing a single flower increases, and as pollination rate decreases with lower flowering intensity, flowering synchrony among plant species is more likely to evolve. We discuss these results in the context of coevolution of plant-pollinator interactions.
