Data from: Spatial distribution of flower color induced by interspecific sexual interaction

Understanding the mechanisms shaping the spatiotemporal distribution of species has long been a central concern of ecology and evolutionary biology. Contemporary patterns of plant assemblies suggest that sexual interactions among species, i.e., reproductive interference, lead to the exclusive distributions of closely related species that share pollinators. However, the fitness consequences and the initial ecological/evolutionary responses to reproductive interference remain unclear in nature, since reproductive isolation or allopatric distribution has already been achieved in the natural community. In Japan, three species of blue-eyed grasses (Sisyrinchium) with incomplete reproductive isolation have recently colonized and occur sympatrically. Two of them are monomorphic with white flowers, whereas the other exhibits heritable color polymorphism (white and purple morphs). Here we investigated the effects of the presence of two monomorphic species on the distribution and reproductive success of color morphs. The frequency and reproductive success of white morphs decreased in area where monomorphic species were abundant, while those of purple morphs did not. The rate of hybridization between species was higher in white morphs than in the purple ones. Resource competition and habitat preference seemed not to contribute to the spatial distribution and reproductive success of two morphs. Our results supported that color-dependent reproductive interference determines the distribution of flower color polymorphism in a habitat, implying ecological sorting promoted by pollinator-mediated reproductive interference. Our study helps us to understand the evolution and spatial structure of flower color in a community.阐明塑造物种时空分布格局的内在机制，长期以来一直是生态学与进化生物学的核心研究议题。现有植物群落的分布格局研究表明，物种间的生殖相互作用——即生殖干扰（reproductive interference）——会导致共享传粉者的近缘物种呈现排他性分布。然而，由于自然群落中往往已形成生殖隔离或异域分布，自然界中生殖干扰对物种适合度的影响，以及物种对生殖干扰的初始生态与进化响应，迄今仍未明确。在日本，3种尚未形成完全生殖隔离的庭菖蒲属（Sisyrinchium）植物近期完成定居并形成同域分布种群。其中两种为开白色花的单态型物种，剩余一种则具有可遗传的花色多态性，包含白色与紫色两种花型（morphs）。本研究针对两种单态型物种的存在对花色多态型种群分布与生殖成功的影响展开了调查。研究发现，在单态型物种密集的区域，白色花型的种群频率与生殖成功均显著下降，而紫色花型则无此变化；不同物种间的杂交率在白色花型中显著高于紫色花型。资源竞争与生境偏好似乎并未对两种花型的空间分布与生殖成功产生影响。本研究结果证实，依赖于花色的生殖干扰决定了同域生境中的花色多态性分布格局，这表明传粉者介导的生殖干扰推动了生态分选过程。本研究有助于我们深入理解群落内植物花色的进化历程与空间结构格局。