Disentangling the importance of climate and species interactions for population persistence

The project will test how populations respond to rapid environmental change. Rapid environmental change threatens the populations of many species. Environmental change can affect populations in many ways. This includes direct effects of non-living aspects of the environment such as temperature. However, environmental change also includes indirect effects caused by changing living components of the environment such as food availability. Predicting population responses to environmental change is difficult because the factors influencing population dynamics are shifting dramatically. In fact, scientists’ ability to make such predictions are limited in several ways. First, studies rarely consider how multiple environmental factors come together across an organism’s life cycle to shape population outcomes. Second, experiments at the population-level are rare. Last, the extent to which population responses to environmental change are shaped by local adaptation to the environment remains unclear. This project addresses these challenges to test how populations respond to multiple environmental factors together. The project will examine how the effects of the environment are shaped by natural selection, and how the relative importance of those factors plays out under rapid environmental change. Furthermore, this research focuses on wild bees, an important but surprisingly understudied group of organisms. Bees are critical to pollination of wild and crop plants. There is evidence of broadscale population declines—but surprisingly little is known about how bee populations are affected by their environment. Therefore, this research is important for advancing population and conservation ecology of bees. The project will provide hands-on research experiences for high school students. The public will also be engaged in the research through a science festival. Using an experimental demography approach, this research investigates the ecological and evolutionary effects of rapid environmental change on population persistence. To do so, researchers will leverage a tractable field-based study system involving a specialist pollinator, its food plant, and its nest parasite. Focusing on the pollinator (an annual, solitary bee), they will use in situ temperature manipulations to estimate vital rate responses to altered environmental conditions under real-world, variable conditions that approximate warmer, future (~2070) and cooler, historic (~1950) conditions. Researchers will then quantify the direct effects of these experimental temperature changes and the subsequent indirect effects mediated by biotic interactions (food resources and parasites) across the life cycle of the bee. To determine the extent to which vital rate responses are adaptive or plastic, temperature manipulations will be performed within a fully crossed reciprocal translocation experiment, in which nests containing developing larvae are exchanged among populations with different climatic histories—warm and cool range edges. The researchers will then use data on vital rate responses from the experiment to parameterize population models for the bee and use perturbation analyses to clarify the relative importance of the abiotic and biotic mechanisms through which rapid environmental change affects population viability. This project will shed new light on how multiple abiotic and biotic factors shape population dynamics in a changing world. 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.