Data from: Spartina alterniflora genotypic identity affects plant and consumer responses in an experimental marsh community

1. Competition and herbivory are ubiquitous processes known to interactively shape plant performance, distribution and community assembly. Likewise, plant genetic variation and associated trait differences can impact both plant-plant and plant-herbivore interactions individually, yet few studies have explored these interactions simultaneously. 2. Salt marsh communities are an ideal system to study these questions, as they are dominated along the Atlantic and Gulf coasts of the United States by a foundation plant species, Spartina alterniflora, with high levels of genetically-based trait variation. Furthermore, consumer pressure and plant competitors are known to influence both the distribution and production of Spartina. We manipulated Spartina genetic identity, neighbor identity (needlerush, Juncus roemerianus), and consumer presence (snail, Littoraria irrorata) in a one-year field experiment in St. Joseph Bay, FL to test how the strength and direction of neighbor and consumer interactions vary by plant genotype. 3. Consumer effects on Spartina were generally stronger and more variable than those of the plant neighborhood, and these effects were generally consistent across Spartina genotypes. However, genotype-specific variation in morphology, phenology, and palatability significantly influenced both consumer and neighbor responses to Spartina: the consumer Littoraria was more likely to climb palatable Spartina genotypes, and neighboring Juncus had shorter stems in the presence of highly productive Spartina genotypes. 4. Synthesis. Our results add to the growing list of examples highlighting the role of intraspecific variation in species interactions, and suggest that variation in these interactions may promote the maintenance of plant genetic variation and community composition.

1. 竞争与植食作用是无处不在的生态过程，已知二者可共同调控植物的生长表现、分布格局与群落构建。同样，植物的遗传变异及其相关性状差异，可分别影响植物间相互作用与植物-植食者相互作用，但目前鲜有研究同时探究这两类相互作用。2. 盐沼群落是研究此类问题的理想体系：美国大西洋与墨西哥湾沿岸的盐沼群落以互花米草（Spartina alterniflora）为建群植物种，该物种存在大量由遗传决定的性状变异。此外，已有研究表明，植食消费者压力与植物竞争者均可影响互花米草的分布与生物量产出。本研究于美国佛罗里达州圣约瑟夫湾开展为期一年的野外操控实验，通过调控互花米草的遗传背景、邻体植物身份（针灯芯草，Juncus roemerianus）以及消费者存在与否（螺类，Littoraria irrorata），旨在探究邻体相互作用与消费者相互作用的强度和方向如何随植物基因型发生变化。3. 相较于植物邻体的影响，植食消费者对互花米草的作用整体更强且变异程度更高，且这些作用在不同互花米草基因型间整体保持一致。然而，互花米草在形态、物候以及适口性上的基因型特异性变异，会显著影响消费者与邻体植物对互花米草的响应：消费者Littoraria irrorata更倾向于攀爬适口性更佳的互花米草基因型，而邻体灯芯草在与高生物量产出的互花米草基因型伴生时，其茎秆长度更短。4. 综合分析：本研究结果进一步扩充了阐明种内变异在物种相互作用中发挥关键作用的实例库，同时表明这类相互作用的变异或可促进植物遗传变异与群落组成的维持。