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 (competition and herbivory) 是自然界中无处不在的生态过程，二者可通过交互作用共同调控植物表现 (plant performance)、空间分布与群落构建 (community assembly)。同理，植物遗传变异及其伴随的性状差异可分别作用于植物-植物互作与植物-植食者互作，但目前同时探究这两类互作的研究仍为数不多。
2. 盐沼群落 (salt marsh communities) 是探究上述科学问题的理想实验系统：美国大西洋沿岸与墨西哥湾沿岸的盐沼群落以建群植物种 (foundation plant species) 互花米草 (Spartina alterniflora) 为绝对优势类群，且该物种存在大量由遗传基础决定的性状变异。此外，已有研究证实消费者取食压力与植物竞争者均可影响互花米草的空间分布与生物量生产。本研究于佛罗里达州圣约瑟夫湾 (St. Joseph Bay, FL) 开展为期一年的野外控制实验，通过人为调控互花米草的遗传背景、邻体物种身份（针蔺，Juncus roemerianus）以及消费者的有无（波纹滨螺，Littoraria irrorata），旨在揭示邻体互作与消费者互作的强度与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，消费者对互花米草的作用强度整体更强、变异程度也更高，且这类效应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 (phenology) 与适口性 (palatability) 上的基因型特异性变异，显著调控了消费者与邻体物种对互花米草的响应模式：消费者波纹滨螺更倾向于寄居于适口性更高的互花米草基因型中，而当邻体为高生物量生产型互花米草基因型时，邻体针蔺的株高会显著降低。
4. 研究综合与结论。本研究结果进一步丰富了种内变异 (intraspecific variation) 在物种互作中发挥关键调控作用的实证案例，并表明这类互作的变异或可促进植物遗传变异与群落组成的长期维持。