School of Ecology and Environment, Northwestern Polytechnical University, Xi'an 710000, China.
Institute of Ecology and Key Laboratory for Earth Surface Processes of the Ministry of Education, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
Sci Adv. 2023 Oct 27;9(43):eadg2555. doi: 10.1126/sciadv.adg2555. Epub 2023 Oct 25.
Floral symmetry plays an important role in plant-pollinator interactions and may have remarkable impacts on angiosperm diversification. However, spatiotemporal patterns in floral symmetry and drivers of these patterns remain unknown. Here, using newly compiled floral symmetry (actinomorphy versus zygomorphy) data of 279,877 angiosperm species and their distributions and phylogenies, we estimated global geographic patterns and macroevolutionary dynamics of floral symmetry. We found that frequency of actinomorphic species increased with latitude, while that of zygomorphic species decreased. Solar radiation, present-day temperature, and Quaternary temperature change correlated with geographic variation in floral symmetry frequency. Evolutionary transitions from actinomorphy to zygomorphy dominated floral symmetry evolution, although the transition rate decreased with decreasing paleotemperature throughout the Cenozoic. Notably, we found that zygomorphy may not favor diversification of angiosperms as previously observed in some clades. Our study demonstrates the influence of (paleo)climate on spatiotemporal patterns in floral symmetry and challenges previous views about role of flower symmetry in angiosperm diversification.
花部形态的对称性在植物与传粉者的相互作用中起着重要作用，可能对被子植物的多样化具有显著影响。然而，花部形态对称性的时空模式及其驱动因素尚不清楚。在这里，我们使用新汇编的 279877 种被子植物的花部形态（辐射对称与左右对称）数据及其分布和系统发育，估计了花部形态对称性的全球地理格局和宏观进化动态。我们发现，辐射对称物种的频率随纬度的增加而增加，而左右对称物种的频率则随纬度的增加而减少。太阳辐射、现今温度和第四纪温度变化与花部形态对称性频率的地理变化相关。从辐射对称到左右对称的进化转变主导了花部形态对称性的进化，尽管在整个新生代，随着古温度的降低，转变率也随之降低。值得注意的是，我们发现，左右对称可能并不像以前在一些类群中观察到的那样有利于被子植物的多样化。我们的研究表明，（古）气候对花部形态对称性的时空模式有影响，并挑战了以前关于花对称性在被子植物多样化中的作用的观点。
