Data from: Assessing changes in arthropod predator-prey interactions through DNA-based gut content analysis - variable environment, stable diet

Analyzing the structure and dynamics of biotic interaction networks and the processes shaping them is currently one of the key fields in ecology. In this paper, we develop a novel approach to gut content analysis, thereby deriving a new perspective on community interactions and their responses to environment. For this, we use an elevational gradient in the High Arctic, asking how the environment and species traits interact in shaping predator-prey interactions involving the wolf spider Pardosa glacialis. To characterize the community of potential prey available to this predator, we used pitfall trapping and vacuum sampling. To characterize the prey actually consumed, we applied molecular gut content analysis. Using joint species distribution models, we found elevation and vegetation mass to explain the most variance in the composition of the prey community locally available. However, such environmental variables had only a small effect on the prey community found in the spider’s gut. These patterns indicate that Pardosa exerts selective feeding on particular taxa irrespective of environmental constraints. By directly modelling the probability of predation based on gut content data, we found that neither trait matching in terms of predator and prey body size nor environmental constraints modified interaction probability. Our results indicate that taxonomy may be more important for predator-prey interactions than environmental constraints or prey traits. The impact of environmental change on predator-prey interactions thus appears to be indirect and mediated by its imprint on the community of available prey.

解析生物相互作用网络的结构与动态，以及塑造这些网络的生态过程，是当前生态学的核心研究领域之一。本研究开发了一种全新的肠道内容物分析方法，由此为群落相互作用及其对环境的响应提供了新的研究视角。为此，我们选取高北极地区的一条海拔梯度样带，探究环境与物种性状如何共同调控以冰川狼蛛（Pardosa glacialis）为代表的捕食者-猎物相互作用。为明确该捕食者可获取的潜在猎物群落组成，我们采用陷阱诱捕法与真空取样法开展调查；为确定其实际取食的猎物类群，我们运用了分子肠道内容物分析技术。借助联合物种分布模型（joint species distribution models）分析，我们发现海拔与植被生物量是解释局域可获取猎物群落组成变异的最主要因素。然而，此类环境变量对蜘蛛肠道内检出的猎物群落组成仅存在微弱影响。该结果表明，冰川狼蛛会对特定分类类群产生取食偏好，且不受环境约束的影响。基于肠道内容物数据直接构建捕食概率模型后，我们发现无论是捕食者与猎物的体型性状匹配度，还是环境约束，均未对相互作用概率产生显著调控作用。本研究结果显示，相较于环境约束或猎物性状，分类类群对捕食者-猎物相互作用的影响更为关键。由此可见，环境变化对捕食者-猎物相互作用的影响是间接的，其作用路径是通过改变可获取猎物群落的组成来实现的。