Data from: Consequences of plant invasions on compartmentalization and species’ roles in plant–pollinator networks

Compartmentalization—the organization of ecological interaction networks into subsets of species that do not interact with other subsets (true compartments) or interact more frequently among themselves than with other species (modules)—has been identified as a key property for the functioning, stability and evolution of ecological communities. Invasions by entomophilous invasive plants may profoundly alter the way interaction networks are compartmentalized. We analysed a comprehensive dataset of 40 paired plant–pollinator networks (invaded versus uninvaded) to test this hypothesis. We show that invasive plants have higher generalization levels with respect to their pollinators than natives. The consequences for network topology are that—rather than displacing native species from the network—plant invaders attracting pollinators into invaded modules tend to play new important topological roles (i.e. network hubs, module hubs and connectors) and cause role shifts in native species, creating larger modules that are more connected among each other. While the number of true compartments was lower in invaded compared with uninvaded networks, the effect of invasion on modularity was contingent on the study system. Interestingly, the generalization level of the invasive plants partially explains this pattern, with more generalized invaders contributing to a lower modularity. Our findings indicate that the altered interaction structure of invaded networks makes them more robust against simulated random secondary species extinctions, but more vulnerable when the typically highly connected invasive plants go extinct first. The consequences and pathways by which biological invasions alter the interaction structure of plant–pollinator communities highlighted in this study may have important dynamical and functional implications, for example, by influencing multi-species reciprocal selection regimes and coevolutionary processes.

隔间化（compartmentalization）指将生态相互作用网络划分为若干物种子集，不同子集间几乎无交互（真正隔间）或子集内部的交互频率显著高于跨子集交互（即模块（modules）），现已被证实是生态群落发挥功能、维持稳定及演化的关键属性。虫媒入侵植物的入侵可能会深刻改变生态相互作用网络的隔间化模式。本研究针对40组成对的植物-传粉者网络（plant–pollinator networks）组成的综合数据集展开分析，以验证该假说。研究结果显示，相较于本地植物，入侵植物对其传粉者的泛化程度更高。其对网络拓扑结构（network topology）的影响并非将本地物种逐出网络，而是入侵植物通过将传粉者吸引至被入侵的模块中，往往会扮演全新的关键拓扑角色（即网络枢纽（network hubs）、模块枢纽（module hubs）与连接者（connectors）），并引发本地物种的角色转变，同时形成规模更大、内部连接更紧密的模块。尽管相较于未入侵网络，入侵网络的真正隔间数量更少，但入侵对模块化（modularity）的影响因研究系统而异。值得注意的是，入侵植物的泛化程度可部分解释这一规律：泛化程度越高的入侵植物，越会降低网络的模块化程度。本研究结果表明，被入侵网络的交互结构发生改变后，其对模拟的随机次级物种灭绝事件的抵抗力更强，但当通常具有高度连接性的入侵植物率先灭绝时，网络则会变得更为脆弱。本研究揭示了生物入侵改变植物-传粉者群落交互结构的途径与后果，这可能具有重要的动态与功能层面的意义——例如，通过影响多物种互惠选择机制与协同演化过程。