Species diversity varies greatly across the different taxonomic groups that comprise the Tree of Life (ToL). This imbalance is particularly conspicuous within angiosperms, but is largely unexplained. Seed mass is one trait that may help clarify why some lineages diversify more than others because it confers adaptation to different environments, which can subsequently influence speciation and extinction. The rate at which seed mass changes across the angiosperm phylogeny may also be linked to diversification by increasing reproductive isolation and allowing access to novel ecological niches. However, the magnitude and direction of the association between seed mass and diversification has not been assessed across the angiosperm phylogeny. Here, we show that absolute seed size and the rate of change in seed size are both associated with variation in diversification rates. Based on the largest available angiosperm phylogenetic tree, we found that smaller-seeded plants had higher rates of diversification, possibly due to improved colonisation potential. The rate of phenotypic change in seed size was also strongly positively correlated with speciation rates, providing rare, large-scale evidence that rapid morphological change is associated with species divergence. Our study now reveals that variation in morphological traits and, importantly, the rate at which they evolve can contribute to explaining the extremely uneven distribution of diversity across the ToL.

在组成生命树（ToL）的不同分类组中，物种多样性差异很大。这种失衡在被子植物中尤为明显，但很大程度上无法解释。种子质量是一个特性，可以帮助阐明为什么某些谱系比其他谱系更具多样性的原因，因为它赋予了对不同环境的适应性，继而影响了物种的形成和灭绝。整个被子植物系统发育中种子质量变化的速率也可以通过增加生殖隔离和允许接触新的生态位来与多样化联系在一起。但是，尚未在整个被子植物系统发育学中评估种子质量与多样化之间关联的大小和方向。这里，我们表明，绝对种子大小和种子大小的变化率都与多样化率的变化有关。基于最大的可利用的被子植物系统发育树，我们发现较小种子的植物具有较高的多样化率，这可能是由于提高了定植潜力。种子大小的表型变化率也与物种形成率密切相关，提供了罕见的大规模证据，表明形态学的快速变化与物种的多样性有关。我们的研究现在表明，形态特征的变化以及重要的是它们演化的速率可以有助于解释整个ToL的多样性极不均匀的分布。我们发现，较小的种子植物具有较高的多样化率，这可能是由于提高了定植潜力。种子大小的表型变化率也与物种形成率密切相关，提供了罕见的大规模证据，表明形态学的快速变化与物种的多样性有关。我们的研究现在表明，形态特征的变化以及重要的是它们演化的速率可以有助于解释整个ToL的多样性极不均匀的分布。我们发现，较小的种子植物具有较高的多样化率，这可能是由于提高了定植潜力。种子大小的表型变化率也与物种形成率密切相关，提供了罕见的大规模证据，表明形态学的快速变化与物种的多样性有关。我们的研究现在表明，形态特征的变化以及重要的是它们演化的速率可以有助于解释整个ToL的多样性极不均匀的分布。