Faculty of Agriculture and Forestry, University of Helsinki, Helsinki, Finland.
Nature Conservation and Landscape Ecology, University of Freiburg, Freiburg, Germany.
Mol Ecol. 2019 Jan;28(2):266-280. doi: 10.1111/mec.14872. Epub 2018 Oct 10.
Analysing 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 observations 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 phylogenetic or environmental constraints modified interaction probability. Our results indicate that taxonomic identity 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.
分析生物相互作用网络的结构和动态以及塑造它们的过程是目前生态学的关键领域之一。在本文中，我们开发了一种新的肠道内容物分析方法，从而为群落相互作用及其对环境的响应提供了新的视角。为此，我们利用北极的海拔梯度，研究环境和物种特征如何相互作用，从而塑造涉及狼蛛 Pardosa glacialis 的捕食者-猎物相互作用。为了描述这种捕食者可利用的潜在猎物群落，我们使用了陷阱和真空采样。为了描述实际被消耗的猎物，我们应用了分子肠道内容物分析。通过联合物种分布模型，我们发现海拔和植被质量可以解释本地可获得的猎物群落组成的最大差异。然而，这些环境变量对蜘蛛肠道中发现的猎物群落只有很小的影响。这些观察结果表明，Pardosa 对特定类群的选择性摄食与环境限制无关。通过直接根据肠道内容物数据建模捕食的概率，我们发现，无论是在捕食者和猎物体型方面的特征匹配，还是在系统发育或环境限制方面，都不会改变相互作用的概率。我们的结果表明，在捕食者-猎物相互作用中，分类身份可能比环境限制或猎物特征更为重要。因此，环境变化对捕食者-猎物相互作用的影响是间接的，是通过其对可用猎物群落的影响来介导的。
