Host specificity in subarctic aphids

The specificity of parasitic interaction depends on the adaptations of both the host and the parasite. Over time, these interactions evolve and change as a result of an “arms race” between host and parasite, and the resulting species-specific adaptations may be maintained, perpetuating these interactions across speciation events. With speciation and species sorting over time, complex systems of interactions evolve. Here, we elucidate some of these interactions using the aphids (Hemiptera: Aphididae) of Churchill as a model system. We analyzed these interactions by testing for two patterns in host-specificity: monophagy and phylogenetic clustering. We defined monophagy as one species feeding upon a single host plant species, an association which is driven by arms races in morphology, chemical resistance/tolerance, and camouflage; this pattern was observed in 7 of 22 aphid species. Secondly, we observed three separate cases where groups of closely related aphid species fed upon individual...寄生相互作用的特异性取决于宿主与寄生物双方的适应性演化特征。随着时间推移，这类相互作用会因宿主与寄生物间的「军备竞赛」而持续演化变迁，由此形成的物种特异性适应性特征得以保留，使得这类相互作用在物种形成事件中得以延续。伴随长期的物种形成与物种筛选过程，复杂的相互作用系统逐步演化形成。本研究以丘吉尔地区的蚜虫（Hemiptera: Aphididae）为模式系统，对其中部分相互作用机制进行阐释。我们通过检验宿主特异性的两类模式来分析这类相互作用：专食性（monophagy）与系统发育聚类（phylogenetic clustering）。我们将专食性定义为：某一蚜虫物种仅取食单一宿主植物物种，这种关联由形态学、化学抗性/耐受性以及伪装等层面的军备竞赛所驱动；在22种蚜虫中，有7种呈现该取食模式。其次，我们观察到三起独立案例：亲缘关系密切的蚜虫类群取食单个……