Data from: Mutualistic strategies minimize coextinction in plant-disperser networks

The global decline of mutualists such as pollinators and seed dispersers may cause negative direct and indirect impacts on biodiversity. Mutualistic network models used to understand the stability of mutualistic systems indicate that species with low partner diversity are most vulnerable to coextinction following mutualism disruption. However, existing models have not considered how species vary in their dependence on mutualistic interactions for reproduction or survival, overlooking the potential influence of this variation on species' coextinction vulnerability and on network stability. Using global databases and field experiments focused on the seed dispersal mutualism, we found that plants and animals that depend heavily on mutualistic interactions have higher partner diversity. Under simulated network disruption, this empirical relationship strongly reduced coextinction because the species most likely to lose mutualists depend least on their mutualists. The pattern also reduced the importance of network structure for stability; nested network structure had little effect on coextinction after simulations incorporated the empirically derived relationship between partner diversity and mutualistic dependence. Our results highlight a previously unknown source of stability in mutualistic networks and suggest that differences among species in their mutualistic strategy, rather than network structure, primarily accounts for stability in mutualistic communities.

传粉者（pollinators）、种子传播者（seed dispersers）等互利共生生物（mutualists）的全球衰退，可能会对生物多样性造成直接与间接的负面影响。用于解析互利共生系统稳定性的互利共生网络模型（mutualistic network models）显示，伙伴多样性较低的物种在互利关系破裂后，最易发生协同灭绝（coextinction）。然而，现有模型未考虑物种在繁殖或生存对互利共生交互的依赖程度上存在差异，忽略了该差异对物种协同灭绝易感性及网络稳定性的潜在影响。本研究依托聚焦于种子传播互利共生关系的全球数据库与野外实验，发现高度依赖互利共生交互的动植物，其伙伴多样性更高。在模拟网络破裂的情境下，这一经验关联显著降低了协同灭绝风险——因为最可能失去共生伙伴的物种，恰恰对其共生伙伴的依赖程度最低。该模式还削弱了网络结构对稳定性的重要性；在模拟实验纳入伙伴多样性与互利共生依赖程度间的经验推导关联后，嵌套网络结构（nested network structure）对协同灭绝的影响微乎其微。本研究结果揭示了互利共生网络中此前未被发现的稳定性来源，并表明：物种间互利共生策略的差异，而非网络结构，是决定互利共生群落稳定性的主要因素。