Data from: Competition for hummingbird pollination shapes flower color variation in Andean Solanaceae

One classic explanation for the remarkable diversity of flower colors across angiosperms involves evolutionary shifts among different types of pollinators with different color preferences. However, the pollinator shift model fails to account for the many examples of color variation within clades that share the same pollination system. An alternate explanation is the competition model, which suggests that color divergence evolves in response to interspecific competition for pollinators, as a means to decrease interspecific pollinator movements. This model predicts color overdispersion within communities relative to null assemblages. Here we combine morphometric analyses, field surveys, and models of pollinator vision with a species-level phylogeny to test the competition model in the primarily hummingbird-pollinated clade Iochrominae (Solanaceae). Results show that flower color as perceived by pollinators is significantly overdispersed within sites. This pattern is not simply due to phylogenetic history: phylogenetic community structure does not deviate from random expectations, and flower color lacks phylogenetic signal. Moreover, taxa that occur in sympatry occupy a significantly larger volume of color space than those in allopatry, supporting the hypothesis that competition in sympatry drove the evolution of novel colors. We suggest that competition among close relatives may commonly underlie floral divergence, especially in species-rich habitats where congeners frequently co-occur.

针对被子植物（angiosperms）花色惊人的多样性，学界经典解释之一涉及不同花色偏好的传粉者（pollinators）之间的演化更替。然而，传粉者更替模型无法解释诸多同一传粉系统下的演化支（clade）内花色变异案例。另一种解释为竞争模型：该模型提出，花色分化是为应对传粉者的种间竞争（interspecific competition），以此减少传粉者的跨物种移动。该模型预测，相较于零假设群落（null assemblages），群落内的花色会呈现过度分散分布。本研究结合形态计量分析（morphometric analyses）、野外调查（field surveys）、传粉者视觉（pollinator vision）模型与物种水平系统发育树（species-level phylogeny），在以蜂鸟传粉为主的茄科（Solanaceae）红丝线亚族（Iochrominae）演化支中检验竞争模型。结果显示，传粉者所感知的花色在样地内呈现显著的过度分散分布。这一模式并非单纯由演化历史导致：群落系统发育结构并未偏离随机预期，且花色不存在系统发育信号（phylogenetic signal）。此外，同域分布的类群在颜色空间中占据的体积显著大于异域分布类群，这支持了同域竞争推动新花色演化的假说。我们认为，近缘类群间的竞争或许普遍驱动了花部分化，尤其是在近缘物种频繁共存的物种丰富型生境中。