Generalist species are important for maintaining network structure and function. Previous studies showed that interactions between generalists persist across sites and years. However, the mechanisms for persistence across spatiotemporal scales are not clear. To address this gap, we collected data on plant--pollinator interactions throughout the flowering period for five years across six plots in a subalpine meadow. We hypothesized that tolerance of environmental variation across time and space plays a key role in species' generalization by regulating spatiotemporal overlap with partners. We found that interactions between species with broader temporal and spatial distributions tended to be more generalized such that interactions near the network core were more persistent across years and plots and within seasons. These results further understanding of networks by linking the role of environmental variation in time and space in organizing interactions, marrying niche concepts that emphasize species environmental constraints and their role in the community.

Most studies of plant--animal mutualistic networks have been temporally static. This approach has revealed many general patterns in the structure of complex webs of mutualistic interactions, but limits our ability to understand the ecological and evolutionary processes that shape these networks, and to predict the consequences of natural and human-driven disturbance on species interactions. The growing availability of temporally explicit data is allowing ecologists to move beyond this static perspective. We review the growing literature dealing with temporal dynamics in plant--animal mutualistic networks including pollination, seed dispersal and ant defence mutualisms. We identify general patterns of temporal variation in these networks across temporal scales. We discuss potential mechanisms underlying variation in interactions, ranging from behavioural and physiological processes at the narrowest temporal scales to ecological and evolutionary processes operating over much broader temporal scales. We conclude by discussing priorities for future research, including an improved understanding of the abiotic and biotic factors driving temporal network change, and further development and refinement of analytical tools. Our review highlights the key role of the importance of considering the temporal dimension for our understanding of the ecology and evolution of complex webs of mutualistic interactions.

Understanding the impacts of global change on mutualistic networks is a major challenge in modern ecology. The gain or loss of particular species and the disruption of key interactions are both consequences and drivers of global change that can lead to the disassembly of complete mutualistic webs. We explored whether the disruption of a hummingbird-mistletoe-marsupial keystone interaction by the invasion of non-native species can have cascading effects on both pollination and seed dispersal networks in the temperate forest of Patagonia. We found that the disruption of the keystone interaction resulted in diverse indirect effects that led to less complex pollination and seed dispersal networks. Similarly, the disruption of the keystone interaction decreased the functional redundancy among generalist plants and pollinators. Our results demonstrate how the disruption of a keystone interaction can have cascading effects through the community, reducing the complexity and stability of ecological networks.