Data from: 28 year temporal sequence of epidemic dynamics in a natural rust – host plant metapopulation

A long-term study of disease dynamics caused by the rust Uromyces valerianae in 31 discrete populations of Valeriana salina provides a rare opportunity to explore extended temporal patterns in the epidemiology of a natural host-pathogen metapopulation. Over a 28-year period, pathogen population dynamics varied across the metapopulation with disease incidence (presence/absence), prevalence (% plants infected) and severity (% leaf area covered by lesions) all showing strong population and year effects, indicative of heterogeneity among years and host populations in the suitability of conditions for the pathogen. Disease incidence within individual host populations was significantly affected by host population size, disease prevalence the previous year and the proximity of neighbouring populations infected in the current year. After accounting for these variables there was still a marked temporal component with winter sea level having a significant effect; as did summer rainfall in the second part of the study period (1997-2011). Disease prevalence was also effected by host population size and disease prevalence in the previous year. However, it was less affected by spatial aspects of disease spread than was disease incidence. Winter sea level and June rainfall significantly affected disease prevalence. Assessment of disease impact on plant performance found strong variation in disease severity associated with the aspect and positioning of host populations. Plants growing in lower disease environments produced significantly more seeds than those growing in high disease sites. Significant variation in reaction to infection by U. valerianae was detected among plants within four populations and between these different populations. Synthesis. The epidemiology of U. valerianae was highly influenced by host population size, previous disease and distance. After accounting for these factors, there was a clear temporal signal of change in disease incidence linked to winter sea level and summer rainfall. These patterns reinforce the importance of considering interactions in multiple populations over long periods of time in order to obtain a clear picture of the variability of disease-induced selection pressures across time and space. The behaviour of the pathogen fitted that predicted for a metapopulation with considerable asynchrony in epidemiological patterns among demes.针对盐生缬草（Valeriana salina）31个离散种群中由缬草单胞锈菌（Uromyces valerianae）引发的病害动态开展的长期研究，为探究自然宿主-病原物集合种群（metapopulation）的流行病学长期时间模式提供了难得契机。 在长达28年的研究周期内，病原物种群动态在整个集合种群中呈现显著异质性：病害发病率（发病与否）、病害普遍率（感染植株百分比）与病害严重度（病斑覆盖叶面积百分比）均表现出强烈的种群效应与年份效应，表明不同年份及宿主种群间的病原适生条件存在差异。 单个宿主种群内的病害发病率显著受宿主种群大小、前一年病害普遍率以及当年感染邻群的空间距离影响。在控制上述变量后，仍存在显著的时间组分：冬季海平面高度具有显著影响，研究后半段（1997-2011年）的夏季降雨量同样存在显著效应。 病害普遍率同样受宿主种群大小与前一年病害普遍率的影响。不过相较于病害发病率，其受病害传播空间特征的影响程度更低。冬季海平面高度与6月降雨量同样对病害普遍率存在显著影响。 针对病害对植株生长表现的影响评估显示，病害严重度与宿主种群的坡向及区位存在显著关联。低病害环境下生长的植株所结种子量显著高于高病害位点的植株。 在4个宿主种群的植株内部以及不同种群之间，均检测到对缬草单胞锈菌侵染的反应存在显著差异。 综合分析：该锈菌的流行病学特征显著受宿主种群大小、既往病害发生情况与空间距离的影响。在控制上述因素后，病害发病率的变化仍存在清晰的时间信号，该信号与冬季海平面高度及夏季降雨量密切相关。上述研究结果进一步凸显了长期、多种群交互研究的重要性——唯有如此才能清晰阐明病害诱导的选择压力在时间与空间维度上的变异规律。该病原物的种群动态符合集合种群的理论预测，即不同局域种群间的流行病学模式存在显著异步性。