The evolutionary ecology of novel plant-pathogen interactions

Novel plant-pathogen combinations occur whenever pathogen or plant species are introduced to regions outside their native range. Whether a pathogen is able to acquire a new host depends on the genetic compatibility between the two, through either preadaptation of the pathogen or subsequent evolutionary change. The ecological outcome of the novel interaction-for example, a spreading disease epidemic or the extinction of an incipient plant invasion-depends on the life history of the pathogen, opportunities for rapid evolution of virulence or resistance, and the presence of a suitable environment. We review recent work on the biology of pathogen virulence and host resistance, their mechanisms, and their costs. We then explore factors influencing the ecological and evolutionary dynamics of novel plant-pathogen interactions, using that evolutionary ecology framework to provide insight into three important practical applications: emerging diseases, biological invasions, and biological control.