Mechanisms that favour rare species are key to the maintenance of diverse communities^1,2,3. One of the most critical tasks for conservation of flowering plant biodiversity is to understand how plant–pollinator interactions contribute to the maintenance of rare species^4,5,6,7. Here we show that niche partitioning in pollinator use and asymmetric facilitation confer fitness advantage of rarer species in a biodiversity hotspot using phylogenetic structural equation modelling that integrates plant–pollinator and interspecific pollen transfer networks with floral functional traits. Co-flowering species filtered pollinators via floral traits, and rarer species showed greater pollinator specialization leading to higher pollination-mediated male and female fitness than more abundant species. When plants shared pollinator resources, asymmetric facilitation via pollen transport dynamics benefitted the rarer species at the cost of more abundant species, serving as an alternative diversity-promoting mechanism. Our results emphasize the importance of community-wide plant–pollinator interactions that affect reproduction for biodiversity maintenance.

有利于稀有物种的机制是维持多样化群落^1,2,3的关键。保护开花植物生物多样性的最关键任务之一是了解植物与传粉者的相互作用如何有助于维持稀有物种^4,5,6,7. 在这里，我们使用系统发育结构方程模型显示传粉媒介使用和不对称促进中的生态位划分赋予稀有物种在生物多样性热点中的适应性优势，该模型将植物 - 传粉媒介和种间花粉转移网络与花卉功能特征相结合。共花物种通过花性特征过滤传粉者，稀有物种表现出更大的传粉者专业化，导致授粉介导的雄性和雌性适应性高于更丰富的物种。当植物共享传粉媒介资源时，通过花粉运输动力学的不对称促进以更丰富的物种为代价使稀有物种受益，作为一种替代的多样性促进机制。