Kniskern Joel M, Rausher Mark D
Department of Biology, Duke University, Durham, North Carolina 27708-0338, USA.
Ecology. 2006 Mar;87(3):675-85. doi: 10.1890/05-1327.
Variation in the environment is common within and between natural populations and may influence selection on plant resistance by altering the level of damage or the fitness consequences of damage from plant enemies. While much is known about how environmental variation influences the amount of damage a plant experiences, few studies have attempted to determine how variation in the environment may alter the fitness consequences of damage, particularly in plant-pathogen interactions. In this work we manipulated a rust pathogen, Coleosporium ipomoeae, in field experiments and showed that this pathogen reduced several components of fitness in its natural host plant, Ipomoea purpurea. Furthermore, we showed that the deleterious effects of C. ipomoeae were variable. We identified variation in the quality of a plant's microenvironment, the abundance of secondary enemy damage, and the length of a growing season as variable components of the environment that may influence the magnitude of damage and tolerance, causing the interaction between C. ipomoeae and I. purpurea to vary from parasitism to commensalism. Considering how environmental variation impacts the magnitude and negative fitness effects of pathogen damage is important to understanding spatially variable selection and coevolution in this and other plant-pathogen interactions.
自然种群内部以及不同自然种群之间，环境变化都很常见，这种变化可能会通过改变植物所遭受的损害程度或植物受敌害损害后的适合度结果，来影响对植物抗性的选择。虽然我们对环境变化如何影响植物所遭受的损害量已经了解很多，但很少有研究试图确定环境变化如何改变损害的适合度结果，尤其是在植物与病原体的相互作用中。在这项研究中，我们在田间试验中对一种锈病病原体——甘薯鞘锈菌进行了操控，结果表明这种病原体降低了其天然寄主植物——紫牵牛的几个适合度组成部分。此外，我们还表明甘薯鞘锈菌的有害影响是可变的。我们确定了植物微环境质量、次生敌害的丰度以及生长季节的长度等环境可变因素，这些因素可能会影响损害程度和耐受性的大小，从而导致甘薯鞘锈菌与紫牵牛之间的相互作用从寄生关系转变为共生关系。了解环境变化如何影响病原体损害的程度和负面适合度效应，对于理解这种以及其他植物与病原体相互作用中的空间可变选择和协同进化至关重要。
