Uniting demographic life history theory and pollination biology to understand the ecological consequences of pollinator declines

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Around the world, pollinators are in decline. Given that almost 90% of flowering plants rely on animal pollination, there is concern that many plants will decline towards extinction alongside their pollinators. Pollination is important because it ensures that plants can make seeds, grow into new plants and keep the species going. Yet, there are many reasons to think that the link between declining numbers of plants and declining numbers of pollinators is not so simple. For example, although it makes sense that a plant would make fewer seeds when there are fewer pollinators around, fewer seeds do not necessarily mean fewer new plants if, for example, the new plants compete for places to live. Fewer seeds could actually result in less competition among new plants, allowing more of them to survive. Furthermore, plants may use other resources not devoted to making seeds to grow larger and survive longer, thus having more chances to reproduce within their lifetime. These examples illustrate how, despite making fewer seeds, enough new plants could be made to keep the species going. A bigger lesson is that ecology is complex; all sorts of hidden strategies are not apparent until you take a closer look. This project will follow the fates of thousands of plants that are exposed to different numbers of pollinators, thereby helping scientists to identify plant species most at risk from pollinator declines and to understand why others are or are not at risk. In addition to data collection, the scientists on this project will help train the next generation of ecologists and will engage the public through an educational film, a blog, and a permanent interactive exhibit. Individual-based population models (integral projection models) will be parameterized with data from a field experiment in which five species of perennial plants receive different pollination treatments: (i) increased pollination, (ii) reduced pollination, (iii) interannually variable pollination, and (iv) an unmanipulated control. All plants will be tagged with a unique identification number and their demographic status assessed annually. Additional germination experiments will be used to parameterize the effect of pollination on recruitment through density-dependent germination and seedling survival. Projections of the population models will show the consequences of pollination for plant population dynamics. Finally, life table response experiments will elucidate specific life history mechanisms by which pollination does or does not affect plant population growth rates (e.g., via trade-offs between growth and reproduction). This project will provide the empirical evidence necessary to bridge conceptual gaps among pollination biology, life history theory, and population dynamics, as well as providing a framework for understanding and predicting the ecological consequences of pollinator declines.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.