It’s all about connections: hubs and invasion in habitat networks

During the early stages of invasion, the interaction between the features of the invaded landscape, notably its spatial structure, and the internal dynamics of an introduced population, has a crucial impact on establishment and spread. By approximating introduction areas as networks of patches linked by dispersal, we characterized their spatial structure with specific metrics and tested their impact on two essential steps of the invasion process: establishment and spread. By combining simulations with experimental introductions of Trichogramma chilonis (Hymenoptera: Trichogrammatidae) in artificial laboratory microcosms, we demonstrated that spread was hindered by clusters and accelerated by hubs but was also affected by small-population mechanisms prevalent for invasions, such as Allee effects. Establishment was also affected by demographic mechanisms, in interaction with network metrics. These results highlight the importance of considering the demography of invaders as well as the st...在生物入侵的早期阶段，被入侵生境的各类特征（尤其是其空间结构）与引入种群的内部动态之间的相互作用，对入侵物种的定殖与扩散过程具有关键性影响。本研究将引入区域近似为通过扩散连接的生境斑块网络，采用特定指标对其空间结构进行量化表征，并检验了该空间结构对入侵过程两大核心环节——定殖与扩散——的影响。通过结合数值模拟与实验室人工微宇宙中的螟黄赤眼蜂（Trichogramma chilonis，膜翅目：赤眼蜂科）人工释放实验，本研究证实：斑块集群会阻碍扩散过程，枢纽斑块则会加速扩散；同时发现入侵过程中普遍存在的小种群机制（如阿利效应（Allee effects））也会对扩散产生影响。定殖过程同样受到种群动态机制的调控，且该机制与网络空间指标存在交互作用。上述研究结果凸显了在入侵生态学研究中，同时考量入侵种群的种群动态以及……的重要性。