Zander Axel, Gravel Dominique, Bersier Louis-Félix, Gray Sarah M
Oecologia. 2016 Feb;180(2):519-28. doi: 10.1007/s00442-015-3476-2.
Introduced top predators have the potential to disrupt community dynamics when prey species are naive to predation. The impact of introduced predators may also vary depending on the stage of community development. Early-succession communities are likely to have small-bodied and fast-growing species, but are not necessarily good at defending against predators. In contrast, late-succession communities are typically composed of larger-bodied species that are more predator resistant relative to small-bodied species. Yet, these aspects are greatly neglected in invasion studies. We therefore tested the effect of top predator presence on early- and late-succession communities that were either naive or non-naive to top predators. We used the aquatic community held within the leaves of Sarracenia purpurea. In North America, communities have experienced the S. purpurea top predator and are therefore non-naive. In Europe, this predator is not present and its niche has not been filled, making these communities top-predator naive. We collected early- and late-succession communities from two non-naive and two naive sites, which are climatically similar. We then conducted a common-garden experiment, with and without the presence of the top predator, in which we recorded changes in community composition, body size spectra, bacterial density, and respiration. We found that the top predator had no statistical effect on global measures of community structure and functioning. However, it significantly altered protist composition, but only in naive, early-succession communities, highlighting that the state of community development is important for understanding the impact of invasion.
当猎物物种对捕食行为缺乏经验时，引入顶级捕食者有可能扰乱群落动态。引入捕食者的影响也可能因群落发展阶段而异。早期演替群落可能有体型小且生长迅速的物种，但不一定善于抵御捕食者。相比之下，晚期演替群落通常由体型较大的物种组成，相对于体型较小的物种，它们对捕食者更具抵抗力。然而，在入侵研究中，这些方面被极大地忽视了。因此，我们测试了顶级捕食者的存在对早期和晚期演替群落的影响，这些群落对顶级捕食者要么缺乏经验，要么有经验。我们使用了紫瓶子草叶内的水生群落。在北美，群落已经经历了紫瓶子草顶级捕食者，因此有经验。在欧洲，这种捕食者不存在，其生态位也未被占据，使得这些群落对顶级捕食者缺乏经验。我们从两个有经验和两个缺乏经验的地点收集了早期和晚期演替群落，这些地点气候相似。然后我们进行了一个共同花园实验，有顶级捕食者和没有顶级捕食者的情况下，我们记录了群落组成、体型谱、细菌密度和呼吸的变化。我们发现顶级捕食者对群落结构和功能的整体测量没有统计学影响。然而，它显著改变了原生生物的组成，但只在缺乏经验的早期演替群落中，这突出了群落发展状态对于理解入侵影响的重要性。
