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

植物病虫害在构建生态群落中起着重要作用；然而，本地和引进的害虫都对野生和管理系统造成了巨大压力，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爆发的范围、频率和严重程度。因此，迫切需要扩展现有的理论来应对这些挑战。在此，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。在植物中，越来越多的研究表明，宿主进化亲缘关系——系统发育——强烈地构建了病原体宿主范围。这种系统发育结构的后果是深远的。例如，病原体的传播速率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根据其引进范围内植物物种与本地范围内植物物种之间的系统发育亲缘关系来估计。此外，我们可以预测，本地害虫对农作物的疾病压力与来自本地植物群落的作物物种的进化独特性呈负相关，而入侵植物的传播与它们的进化独特性呈正相关。本研究的一个主要目标是提高我们目前对植物宿主-害虫关系的理解，更好地预测新出现的植物害虫的疾病影响，并指导积极的害虫监测。首先，我的目标是利用现有的植物-害虫数据库和植物的大系统发育来描述植物-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，我将使用这些数据来模拟害虫在植物宿主之间共享的可能性，并根据宿主物种之间的进化距离重新定义害虫的宿主宽度。其次，我将使用植物标本馆收藏的大量历史记录来模拟随着时间的推移而变化的病虫害压力，并使用该模型来预测害虫宿主的扩张，然后在现场进行验证。第三，我将利用酿酒葡萄真菌病原菌Botryosphaeriaceae的实验交叉感染作为模型系统来评估系统发育宿主宽度与毒力之间的关系。我在上面概述的建议框架有望为作物疾病和害虫风险模型提供信息，提高对入侵物种传播和本地物种中新出现的病原体爆发的预测，并有助于我们对物种共存和害虫和病原体在调节自然群落多样性中的重要性的基本理解。

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 relatedness-phylogeny-strongly 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.