Data from: 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 plant species (examples of phylogenetic clustering). One explanation for uncovering species-specific interactions in a recently deglaciated, sub-arctic locality is that the species involved in the associations moved north together. Testing different levels of specificity in species interactions allows us to accurately elucidate these patterns and gives us insight into where to direct future research.

寄生互作的特异性取决于宿主与寄生物双方的适应性。随着时间推移，这类互作会因宿主与寄生物间的“军备竞赛”而演化变迁，由此产生的物种特异性适应性得以保留，进而在物种形成事件中维持这些互作关系。伴随物种形成与物种分选过程，复杂的互作系统逐渐演化形成。本研究以丘吉尔地区的蚜虫（半翅目：蚜科）为模式系统，阐明其中部分互作机制。我们通过检验宿主特异性的两类模式——单食性（monophagy）与系统发育聚类（phylogenetic clustering），分析了这类互作关系：将单食性定义为某一昆虫物种仅取食单一宿主植物物种的现象，这类关联由形态、化学抗性/耐受性以及伪装等方面的军备竞赛所驱动；在22种蚜虫中，有7种符合该模式。其次，我们观测到3组独立案例：亲缘关系较近的蚜虫类群仅取食单一宿主植物物种，即系统发育聚类的实例。对于在近期冰消的亚北极区域发现物种特异性互作关系，一种解释是参与该互作的物种曾一同向北扩散。对物种互作中不同特异性层级的检验，不仅能帮助我们精准阐明这类模式，还能为未来的研究方向提供参考。