The importance of variation to the outcomes of interactions between organisms is understudied. Typically, studies of ecological and evolutionary interactions focus on means of interaction metrics, although other aspects of distributions of those metrics, such as variance and skew, can also be critical for ecology and evolution. The Herbivory Variability Research Coordination Network will advance science by expanding thinking beyond a focus on means to include the causes and consequences of variability itself. To illustrate, variation in temperature and precipitation can be more important than averages to species performance and interactions. Less appreciated is that variation in the abundance of one species across space and time can drive the outcome of its interactions with other species and may even impact evolutionary trajectories. Understanding the role of variability in the ecology and evolution of species interactions is becoming increasingly important as climate change and biodiversity loss lead to increased environmental variability and decreased biological variability. The network will focus on herbivory because it is an ecologically and economically important interaction that is easy to measure, exhibits great variation within and among species, and is a key variable in many important ecological and evolutionary theories. The foundations developed for studying variability in herbivory, however, could be extended to better understand any type of species interactions. Because the causes and consequences of interaction variability relate to so many disciplines, the network will bring together ecologists, evolutionary biologists, mathematicians, statisticians, chemists, and other scientists to collaborate via working groups that tackle synthesis, theory, data, and education projects.This project will also afford research training opportunities. <br/><br/>This project will form a Research Coordination Network (The Herbivory Variability Network, “HerbVar”), which will bring together scientists from across fields and career stages with the common goal of understanding the causes and consequences of interaction variability. This diverse and interdisciplinary network will (1) synthesize existing data and knowledge on interaction variability and identify directions for future work; (2) assemble a quantitative toolbox for studying variability in species interactions; (3) coordinate globally distributed data collection; and (4) educate students about the importance of variability and how to study it.<br/><br/>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.