Climate modulation of phylogenetic and functional constraints on fruit volume: A case study of Chinese angiosperms

Fruit volume is a pivotal reproductive trait that influences dispersal, seed predation, and offspring establishment, yet its large-scale drivers remain poorly understood. Here, we compiled phylogenetic, functional, and climatic data for 2668 angiosperm species sampled from 22 ecological stations across China to disentangle the relative contributions of evolutionary history, plant traits, and climate to interspecific fruit volume variation. We quantified phylogenetic signal, fitted phylogenetic generalized linear models and mixed-effects models, and conducted hierarchical variance partitioning to evaluate predictor importance. Fruit volume exhibited a strong phylogenetic signal (Pagel's λ = 0.916), with phylogenetic relationships explaining 64.71% of the variance. Functional traits, particularly plant height (11.99%) and growth form (9.97%), also contributed significantly. Importantly, the explanatory power of phylogenetic relationships declined in warmer environments, where the effects of plant height and leaf area increased, indicating that phylogenetic niche conservatism is context dependent. These findings highlight that this phylogenetic pattern reflects the dominant role of evolutionary history in shaping fruit volume while revealing how climate modulates the relative importance of phylogenetic history and functional traits during community assembly. By integrating macroevolutionary patterns with ecological filtering, this study provides new insights into the evolutionary ecology of plant reproduction under environmental change.