Data from: Macroevolution of floral scent chemistry across radiations of male euglossine bee-pollinated plants

Floral volatiles play key roles as signaling agents that mediate interactions between plants and animals. Despite their importance, few studies have investigated broad patterns of volatile variation across groups of plants that share pollinators, particularly in a phylogenetic context. The "perfume flowers", Neotropical plant species exhibiting exclusive pollination by male euglossine bees in search of chemical rewards, present an intriguing system to investigate these patterns due to the unique function of their chemical phenotypes as both signaling agents and rewards. We leverage recently-developed phylogenies and knowledge of biosynthesis along with decades of chemical ecology research to characterize axes of variation in the chemistry of perfume flowers, as well as understand their evolution at finer taxonomic scales. We detect pervasive chemical convergence, with many species across families exhibiting similar volatile phenotypes. Scent profiles of most species are dominated by compounds of either the phenylpropanoid or terpenoid biosynthesis pathways, while terpenoid compounds drive more subtle axes of variation. We find recapitulation of these patterns within two independent radiations of perfume flower orchids, in which we further detect evidence for rapid evolution of divergent floral chemistries, consistent with the putative importance of scent in the process of adaptation and speciation.

植物花香挥发物作为信号媒介，在介导动植物相互作用中发挥核心功能。尽管其生态重要性不言而喻，但目前鲜有研究针对共享传粉者的植物类群开展挥发物变异的宏观格局分析，且尤其缺乏基于系统发育背景的相关探究。“香水花”（perfume flowers）是一类新热带区植物，其传粉过程仅依赖于寻求化学报酬的雄性兰花蜂（euglossine bees），且其化学表型兼具信号媒介与报酬的双重独特功能，因此是探究上述挥发物变异格局的理想研究体系。本研究借助新近构建的系统发育框架、生物合成相关的科学认知，结合数十年化学生态学研究成果，系统表征了香水花化学组成的变异维度，并进一步解析了其在更精细分类阶元下的演化规律。研究发现存在广泛的化学趋同现象，多个科的诸多物种呈现出相似的挥发物表型。多数物种的花香谱以苯丙烷类（phenylpropanoid）或萜类（terpenoid）生物合成途径产生的化合物为主，而萜类化合物则驱动了更细微的变异维度。我们在两个独立辐射演化的香水花兰科类群中均观察到了上述格局的重现，且进一步发现了花部化学成分快速分化演化的证据，这与花香在植物适应与物种形成过程中的推测性重要性相吻合。