Generalism in resource use is commonly considered a critical driver of population success, species distribution and extinction risk. This idea can be questioned as generalism may be a result rather than the cause of species abundance and range size. We tested these contrasting causal hypotheses focusing on host use in three databases encompassing approximately 44,000 mutualistic (hummingbird–plant), commensalistic (lichen–plant) and parasitic (flea–mammal) interactions in 617 ecological communities across the Americas and Eurasia. Across all interaction types, our analyses indicated that range size and abundance influence the probability of encountering hosts and set the arena for species to express generalism potentials or adapt to new hosts. Hence, our findings support the hypothesis that generalism is a consequence of species ecological success. This highlights the importance of ecological opportunity in driving species characteristics considered key for their survival and conservation.

资源利用的普遍性通常被认为是种群成功、物种分布和灭绝风险的关键驱动因素。这种想法可能会受到质疑，因为普遍主义可能是物种丰富度和范围大小的结果而不是原因。我们在三个数据库中测试了这些对比因果假设，重点关注宿主的使用，涵盖美洲和欧亚大陆 617 个生态群落中约 44,000 个互惠（蜂鸟 - 植物）、共生（地衣 - 植物）和寄生（跳蚤 - 哺乳动物）相互作用。在所有相互作用类型中，我们的分析表明，范围大小和丰度会影响遇到宿主的概率，并为物种表达通用潜力或适应新宿主奠定基础。因此，我们的研究结果支持这样的假设：普遍主义是物种生态成功的结果。这凸显了生态机会在驱动物种特征方面的重要性，这些特征被认为是其生存和保护的关键。