Data from: Feeding evolution of a herbivore influences an arthropod community through plants: implications for plant-mediated eco-evolutionary feedback loop

1. Genetic variation in individual species can have important ecological consequences, and sometimes, these interactions are mediated through another species. For example, genetic variation in an herbivore could alter plant responses that then influence other plant-associated arthropods. However, few systems have experimentally tested the ecological consequences of genetic variation as mediated through other species, especially within the same trophic community context. 2. I studied how evolution of feeding preference in the willow leaf beetle (Plagiodera versicolora), which occurs under selection in a herbivore community context, feeds back to an arthropod community through plant-mediated indirect interactions. Previous studies show beetle populations locally adapt distinct preferences ranging from the gourmet-type, which feeds exclusively on new leaves of willows, to the no-preference (no-pref) type, which displays non-preferential feeding on leaves of different ages. 3. I conducted field experiments at two sites that mimicked evolutionary changes in the feeding preference of the leaf beetle. I manipulated the composition of leaf beetle feeding types for 6 days in spring and then investigated subsequent development of arthropod communities. I found that initial herbivory by a higher proportion of gourmet-type beetles led to lower subsequent abundance of conspecific beetle larvae. In contrast, a higher proportion of gourmet-type beetles resulted in higher abundance of aphids. Aphid-tending ants also increased with the increasing abundance of aphids. As a result, species diversity of arthropod communities decreased with the proportion of gourmet-type beetles in the initial beetle treatment. 4. Community assembly dynamics were significantly influenced by interactive effects between the initial beetle treatment and subsequent colonizer species identities. Thus, beetle genetic variation had long-lasting effects through a temporal chain of indirect interactions likely mediated through induced plant responses and the abundance of aphids. 5. Synthesis. Evolutionary changes in feeding traits within an herbivore species had profound but predictable impact on local arthropod communities. Because the feeding evolution of herbivores nearly always occurs in a community context, plant-mediated feedback loops between the evolution and ecological community of arthropods may be widespread in nature.

1. 单个物种种内的遗传变异可产生重要的生态学效应，且此类互作有时会通过第三类物种介导。例如，植食性昆虫（herbivore）的遗传变异可改变植物的响应特征，进而影响其他与植物关联的节肢动物（arthropod）。然而，鲜有实验系统探究通过其他物种介导的遗传变异生态学效应，尤其是在同一营养级群落（trophic community）背景下。
2. 本研究探讨了柳蓝叶甲（willow leaf beetle, *Plagiodera versicolora*）取食偏好的演化如何通过植物介导的间接互作，反馈作用于节肢动物群落；该演化过程发生于植食性昆虫群落的选择压力环境中。既往研究显示，柳蓝叶甲种群会局部适应两类截然不同的取食偏好：一类为专食型（gourmet-type），仅取食柳树的新生叶片；另一类为无偏好型（no-preference, no-pref），可无差别取食不同叶龄的叶片。
3. 本研究于两个野外站点开展模拟柳蓝叶甲取食偏好演化的田间实验：于春季操控柳蓝叶甲取食型别的组成，持续6天，随后调查节肢动物群落的后续演替动态。结果发现，初始处理中更高比例的专食型甲虫取食所造成的植食影响，会导致后续同种甲虫幼虫的丰度显著降低；与之相反，专食型甲虫占比更高则会提升蚜虫（aphid）的丰度，而护蚜蚂蚁（aphid-tending ants）的数量也随蚜虫丰度的增加而上升。最终，节肢动物群落的物种多样性随初始处理中专食型甲虫的占比升高而降低。
4. 群落组装动态显著受初始甲虫处理与后续拓殖物种身份间交互效应的调控。据此可知，甲虫的遗传变异可通过一条随时间推进的间接互作链条产生持久效应，该过程大概率由植物诱导响应及蚜虫丰度变化所介导。
5. 综合分析：植食性昆虫物种种内取食性状的演化改变可对局部节肢动物群落产生深刻且可预测的影响。由于植食性昆虫的取食演化几乎总是发生在群落背景中，因此演化与节肢动物生态群落之间的植物介导反馈环可能在自然界中广泛存在。