The Impact of Plant Enemies Shows a Phylogenetic Signal

The host ranges of plant pathogens and herbivores are phylogenetically constrained, so that closely related plant species are more likely to share pests and pathogens. Here we conducted a reanalysis of data from published experimental studies to test whether the severity of host-enemy interactions follows a similar phylogenetic signal. The impact of herbivores and pathogens on their host plants declined steadily with phylogenetic distance from the most severely affected focal hosts. The steepness of this phylogenetic signal was similar to that previously measured for binary-response host ranges. Enemy behavior and development showed similar, but weaker phylogenetic signal, with oviposition and growth rates declining with evolutionary distance from optimal hosts. Phylogenetic distance is an informative surrogate for estimating the likely impacts of a pest or pathogen on potential plant hosts, and may be particularly useful in early assessing risk from emergent plant pests, where critical decisions must be made with incomplete host records.植物病原菌与植食性昆虫的寄主范围（host range）存在系统发育约束（phylogenetic constraint），即亲缘关系相近的植物物种更易共享同类害虫与病原菌。本研究对已发表的实验研究数据开展重新分析，旨在检验寄主-天敌互作的严重程度是否存在类似的系统发育信号（phylogenetic signal）。植食性昆虫与病原菌对寄主植物的危害程度，随其与受害最严重的靶标寄主之间的系统发育距离（phylogenetic distance）增加而稳步下降。该系统发育信号的陡峭程度，与此前针对二元响应寄主范围（binary-response host ranges）所测得的结果相近。天敌的行为与发育同样表现出此类系统发育信号，但强度较弱：其产卵率与生长速率随与最优寄主（optimal host）之间的进化距离（evolutionary distance）增加而下降。系统发育距离可作为有效替代指标，用于估算害虫或病原菌对潜在植物寄主的潜在危害程度；在需依据不完整寄主记录做出关键决策的新兴植物害虫（emergent plant pests）风险早期评估中，该指标尤为实用。