Data from: Local extinctions of obligate frugivores and patch size reduction disrupt the structure of seed dispersal networks

A central problem in ecology is to understand how human impacts affect plant-animal interactions that lead to effective seed dispersal services for plant communities. Seed dispersal services are the outcome of plant-frugivore interactions that often form local networks of interacting species. Recent work has shown that some frugivorous bird species are more critical to network organization than others. Here, we explore how patch size and the potential local extinctions of obligate frugivorous birds affect the reorganization of seed dispersal networks. We examined the structure of 20 empirical seed dispersal networks documented across tropical avian assemblages occupying widely variable habitat patch sizes, a surrogate of the amount of remaining habitat. Networks within small forest patches consistently supported both lower plant and bird species richness. Forest patch size was positively associated with nestedness, indicating that reductions in patch size disrupted the nested organization of seed dispersal networks. Obligate frugivores, especially large-bodied species, were almost entirely absent from small forest patches. Analysis at the species level showed that obligate frugivores formed the core of interacting species, connecting species within a given seed dispersal network. Our combined results revealed that patch size reduction erodes frugivorous bird diversity, thereby affecting the integrity of seed dispersal networks. We highlight the importance of conserving large forest patches to maintain tropical forest functionality.

生态学的核心议题之一，是解析人类活动如何影响那些可为植物群落提供有效种子传播服务的动植物相互作用。种子传播服务是植物与食果动物相互作用的产物，这类相互作用往往会形成局部的物种互作网络。近期研究表明，部分食果鸟类物种对网络结构的维系作用较其他物种更为关键。本研究旨在探讨生境斑块面积，以及专性食果鸟类的潜在局地灭绝，将如何影响种子传播网络的重构。我们对20个基于热带鸟类群落构建的实测种子传播网络进行了分析，这些群落所处的生境斑块面积跨度极大，而斑块面积可作为剩余生境总量的替代指标。小型森林斑块内的网络，其植物与鸟类的物种丰富度均显著更低。森林斑块面积与网络嵌套性呈正相关关系，这表明斑块面积缩减会破坏种子传播网络的嵌套组织结构。专性食果鸟类，尤其是体型较大的类群，几乎完全缺失于小型森林斑块中。物种层面的分析显示，专性食果鸟类构成了互作物种的核心类群，在给定的种子传播网络中承担着不同物种间的连接功能。综合上述研究结果，我们发现斑块面积缩减会侵蚀食果鸟类的多样性，进而损害种子传播网络的完整性。本研究强调，保护大型森林斑块对维持热带森林生态系统功能具有至关重要的意义。