Disease in Natural Plant Populations, Communities, and Ecosystems: Insights into Ecological and Evolutionary Processes

Given the diversity of both pathogens and plants, generalizations are challenging. However, it is clear that pathogens can reduce survival and reproduction of individual plants, that disease can limit plant population growth, and that host-pathogen interactions at larger spatial scales (metapopulations, geographic distributions) are not necessarily predictable from small-scale studies. These ecological studies cannot be divorced from genetic investigations, given both the prevalence of genetic variation for resistance and virulence and the need for an evolutionary ecology approach to understand phenomena such as host shifts. At the community level of organization, diseases can lead to increases or decreases in plant diversity. Research on generalist pathogens is particularly important, with recent work exploring both the ecological consequences of shared pathogens (e.g., pathogen spillover, apparent competition) and the role of plant phylogenetic relationships in host ranges. Studies of feedback between soil microbes (including pathogens) and plant species has been significant, in part because it provides new ways of explaining the coexistence of multiple species in plant communities. Community level research, in turn, often has links to ecosystem level studies. Recent work suggests not only that changes in temperature, greenhouse gases, and nutrients can alter disease levels but also that plant diseases and their effects can alter ecosystem properties. Studies on plant disease are thus an important component of global climate change research. © 2010 The American Phytopathological Society.