Departamento de Botânica, Laboratório de Fenologia, Instituto de Biociências, UNESP-Universidade Estadual Paulista, 13506-900, Rio Claro, São Paulo, Brasil.
Department Biology, Institute of Sensory Ecology, Heinrich-Heine-University Düsseldorf, 40225, Düsseldorf, Germany.
New Phytol. 2019 Apr;222(2):1112-1122. doi: 10.1111/nph.15594. Epub 2018 Dec 18.
Colour signals are the main floral trait for plant-pollinator communication. Owing to visual specificities, flower visitors exert different selective pressures on flower colour signals of plant communities. Although they evolved to attract pollinators, matching their visual sensitivity and colour preferences, floral signals may also evolve to avoid less efficient pollinators and antagonistic flower visitors. We evaluated evidence for the bee avoidance hypothesis in a Neotropical community pollinated mainly by bees and hummingbirds, the campo rupestre. We analysed flower reflectance spectra, compared colour variables of bee-pollinated flowers (bee-flowers; 244 species) and hummingbird-pollinated flowers (hummingbird-flowers; 39 species), and looked for evidence of bee sensorial exclusion in hummingbird-flowers. Flowers were equally contrasting for hummingbirds. Hummingbird-flowers were less conspicuous to bees, reflecting mainly long wavelengths and avoiding red-blind visitors. Bee-flowers reflected more short wavelengths, were more conspicuous to bees (higher contrasts and spectral purity) than hummingbird-flowers and displayed floral guides more frequently, favouring flower attractiveness, discrimination and handling by bees. Along with no phylogenetic signal, the differences in colour signal strategies between bee- and hummingbird-flowers are the first evidence of the bee avoidance hypothesis at a community level and reinforce the role of pollinators as a selective pressure driving flower colour diversity.
颜色信号是植物与传粉者之间交流的主要花朵特征。由于视觉的特殊性，花访客对植物群落的花朵颜色信号施加了不同的选择压力。尽管花朵颜色信号是为了吸引传粉者而进化的，以匹配它们的视觉敏感性和颜色偏好，但它们也可能进化为避免效率较低的传粉者和敌对的花访客。我们在主要由蜜蜂和蜂鸟授粉的新热带群落中评估了避免蜜蜂假说的证据，该群落为旱地群落。我们分析了花朵的反射光谱，比较了蜜蜂授粉花朵（蜜蜂花；244 种）和蜂鸟授粉花朵（蜂鸟花；39 种）的颜色变量，并寻找蜂鸟花中蜜蜂感官排斥的证据。花朵对蜂鸟来说同样具有对比度。蜂鸟花对蜜蜂的吸引力较小，主要反射长波长，避免红盲访客。蜜蜂花反射更多的短波长，比蜂鸟花对蜜蜂更显眼（更高的对比度和光谱纯度），并且更频繁地显示花朵导向，有利于蜜蜂吸引、识别和处理花朵。除了没有系统发育信号外，蜜蜂花和蜂鸟花之间在颜色信号策略上的差异是在群落水平上首次证明避免蜜蜂假说的证据，并加强了传粉者作为驱动花朵颜色多样性的选择压力的作用。
