Towards a phylogenetic ecology of plant pests and pathogens: using evolutionary history to model species interactions

植物害虫和病原体在构建生态群落中起着重要作用，但本地和外来有害生物都对野生和管理系统造成巨大压力，并对粮食安全构成威胁。气候变暖可能会进一步增加未来病虫害暴发的范围、频率和严重程度。因此，迫切需要对当前的理论进行扩展，以应对这些挑战。在这里，我建议建立一个新的系统发育框架来研究植物和害虫的相互作用。在植物方面，越来越多的工作表明，寄主进化相关的次生遗传强烈地构成了病原菌的寄主范围。这种系统发育结构的后果是深远的。例如，病原体传播的速度将由群落中寄主物种的分类组成来调节，而非本地有害生物建立的可能性可以从其引入范围内的植物物种与其本地范围内的植物物种之间的系统发育关系来估计。此外，我们预测，本地害虫对农作物的疾病压力将与本地植物群落中作物物种的进化独特性呈负相关，而入侵植物的传播将与其进化独特性呈正相关。 这项研究的一个主要目标是提高我们目前对植物寄主-害虫关系的理解，更好地预测新出现的植物有害生物对疾病的影响，并指导积极主动的有害生物监测。首先，我的目标是利用现有的植物-害虫数据库和植物的巨型系统发育图来描述植物-害虫相互作用的系统发育结构，以描述害虫在植物生命树上的系统发育分布。然后，我将使用这些数据对植物寄主之间共享害虫的可能性进行建模，并根据寄主物种之间的进化距离重新定义害虫的寄主广度。其次，我将使用标本馆藏的大量历史记录来模拟虫害和疾病压力随时间的变化，并使用这个模型来生成虫害宿主扩展的预测，然后可以在田间进行验证。第三，以酿酒葡萄病原菌Botryosphaeriaceae的实验交叉侵染为模型系统，评价系统发育寄主广度与致病力的关系。 我上面概述的拟议框架有望为作物中的病虫害风险模型提供信息，改进对入侵物种传播和本地物种中新出现的病原体暴发的预测，并有助于我们从根本上理解物种共存以及害虫和病原体在调节自然群落多样性方面的重要性。

Plant pests and pathogens play an important role in structuring ecological communities; yet both native and introduced pests impose significant pressure on wild and managed systems, and pose a threat to food security. A warming climate is likely to further increase the range, frequency and severity of pest and disease outbreaks in the future. There is a critical need, therefore, to expand on current theory to address these challenges. Here, I propose to develop a novel phylogenetic framework for the study of plant and pest interactions. In plants, a growing body of work has suggested that host evolutionary relatednessphylogenystrongly structures pathogen host range. The consequences of such phylogenetic structuring are profound. For example, rates of pathogen spread will be mediated by the taxonomic composition of the host species in a community, and the likelihood of non-native pest establishment may be estimated from the phylogenetic relatedness between the plant species in its introduced range and those in its native range. In addition, we would predict that disease pressure on agricultural crops from native pests will covary negatively with the evolutionary distinctiveness of the crop species from the native plant community, while the spread of invasive plants will covary positively with their evolutionary distinctiveness. A major goal of this research is to improve on our current understanding of host-pest associations in plants, better predict disease impacts of new and emerging plant pests, and guide proactive pest surveillance. First, I aim to characterise the phylogenetic structure of plant-pest interactions using existing plant-pest databases and a mega-phylogeny for plants to describe the phylogenetic distribution of pests across the plant tree-of-life. I will then use these data to model the likelihood of pest sharing among plant hosts, and to redefine the host breadth of pests based on the evolutionary distances separating host species. Second, I will use the vast historical record housed in herbarium collections to model shifting pest and disease pressures through time, and use this model to generate predictions of pest host-expansion which can then be validated in the field. Third, I will evaluate the relationship between phylogenetic host-breadth and virulence using experimental cross infections of the wine-grape fungal pathogen Botryosphaeriaceae as a model system. The proposed framework I outline above holds promise to inform models of disease and pest risk in crops, improve prediction of invasive species spread and emerging pathogen outbreaks in native species, and contribute to our fundamental understanding of species coexistence and the importance of pests and pathogens in regulating diversity in natural communities.