Contrasting effects of frugivore assemblages and phylogeny on global variation in fruit length and width

Nowadays, the evolution of fruit size is still poorly understood though theories of coevolution between fleshy fruits and frugivores have long pointed out the effects of different-sized frugivores and phylogeny. We compile a global-scale dataset on fruit traits of 312 fleshy-fruited plants and frugivore body size from over 300 interaction networks exposed to very different suites of frugivores, and reveal a global positive relationship between frugivore body size and fruit size, i.e., length and width. Using partial R2s model that accounts for species’ shared evolutionary histories, we first show that global variation in fruit width is explained by frugivorous assemblages rather than phylogeny and leaf area. Despite significant evolutionary correlation between fruit length and width, fruit length appears to be more phylogenetically constrained and less sensitive to frugivore-driven selection than width. Our large-scale study provides first evidence of strong phylogenetic constraints of fruit length and frugivore-driven selection on fruit width, providing a novel mechanistic explanation for better understanding the evolution of fruit size across fleshy-fruited plant species.

尽管长期以来肉质果实与食果动物的协同进化理论已阐明不同体型食果动物以及系统发育对果实大小的潜在影响，但目前果实大小的演化机制仍未得到充分解析。本研究整合了来自300余个受不同类群食果动物作用的物种互作网络的全球尺度数据集，涵盖312种肉质果实植物的果实性状与食果动物体型信息，并揭示了食果动物体型与果实大小（包括果实长度与宽度）之间的全球尺度正相关关系。本研究采用考虑物种共享演化历史的偏决定系数（partial R²s）模型，首次证实：果实宽度的全球变异主要由食果动物群落所解释，而非系统发育与叶面积。尽管果实长度与宽度间存在显著的演化相关性，但果实长度似乎更受系统发育约束，且相较于果实宽度，其对食果动物驱动的选择压力的敏感性更低。本项大规模研究首次为果实长度的强系统发育约束以及食果动物驱动的果实宽度选择提供了直接实证证据，为理解全球肉质果实植物类群的果实大小演化机制提供了全新的机理性解释。