Data and code for: Past and future extinctions shape the body size - fruit size relationship between palms and mammalian frugivores

The dispersal of seeds by mammalian frugivores influences the structure and composition of plant communities, but most ecosystems have undergone defaunation over thousands of years, a process that continues today. Understanding how past defaunation has affected fruit-frugivore interactions will thus provide insights into how ecosystems may respond to future frugivore loss. By integrating palm and mammalian frugivore trait and occurrence data worldwide, we reveal a global positive relationship between fruit size and body size of frugivore assemblages. Global variation in fruit size is better explained by present-day frugivore assemblages compared to those of the Late Pleistocene (including extinct species), suggesting a substantial ecological and evolutionary reorganization after Pleistocene mammal extinctions. Interestingly, the reverse is true for the Neotropics where some large-fruited palm species may have persisted over thousands of years following extinction of their main seed dispersers. Simulations of frugivore extinction over the next 100 years suggest that changes in body size will require up to a 4% assemblage-level decrease in palm fruit sizes to maintain the current global frugivore body size - fruit size relationship. Absolute changes in assemblage-level means of palm fruit size were on average up to two-fold higher than observed species-level estimates of seed size change following defaunation. Overall, our results suggest that while some large-fruited palms may persist after the loss of their main dispersers, many palms may be unable to keep pace with future defaunation through evolutionary changes in fruit size alone. The burden of the impact of the extinction of seed dispersers will probably be disproportionately borne by large-fruited palms, possibly over thousands of years to come.

Methods
Please refer to the Methods section and Supplementary Information of the published article.

哺乳动物食果动物对种子的传播过程，会影响植物群落的结构与组成，但绝大多数生态系统在数千年来均经历了动物区系衰减（defaunation），且该过程至今仍在持续。因此，厘清过去的动物区系衰减如何作用于果实-食果动物互作关系，将为理解生态系统对未来食果动物丧失的响应机制提供重要见解。本研究团队整合了全球范围内棕榈科植物与哺乳动物食果动物的功能性状及分布数据，结果揭示果实尺寸与食果动物群落的身体尺寸之间存在全球性正相关关系。相较于更新世晚期（含已灭绝物种）的食果动物群落，现生食果动物群落更能解释全球果实尺寸的变异，这表明更新世哺乳动物灭绝事件后，生态系统发生了显著的生态与进化重组。值得注意的是，新热带界（Neotropics）的情况恰好相反：部分结大型果实的棕榈物种，或许在其主要种子传播者灭绝后的数千年里依然得以存续。针对未来100年内食果动物灭绝的模拟研究显示，若要维持当前全球食果动物身体尺寸-果实尺寸的对应关系，群落层面的棕榈果实尺寸平均需下降至多4%。群落层面棕榈果实尺寸均值的绝对变化幅度，平均可达已有研究中记录的动物区系衰减后种子尺寸物种级变化的两倍之多。总体而言，本研究结果表明：尽管部分结大型果实的棕榈物种在丧失主要传播者后仍可存续，但多数棕榈物种或许无法仅通过果实尺寸的进化变化，跟上未来动物区系衰减的步伐。种子传播者灭绝所带来的影响负担，大概率将不成比例地由结大型果实的棕榈物种承担，且这一过程可能持续数千年之久。

方法
请参阅已发表论文的方法部分与补充信息。