Aguiar João Marcelo Robazzi Bignelli Valente, Maciel Artur Antunes, Santana Pamela Cristina, Telles Francismeire Jane, Bergamo Pedro Joaquim, Oliveira Paulo Eugênio, Brito Vinicius Lourenço Garcia
Programa de Pós-Graduação em Entomologia, Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil.
Programa de Pós-Graduação em Ecologia e Conservação dos Recursos Naturais, Instituto de Biologia, Universidade Federal de Uberlândia, Uberlândia, Brazil.
Front Plant Sci. 2020 Nov 9;11:589300. doi: 10.3389/fpls.2020.589300. eCollection 2020.
Flower color has been studied in different ecological levels of organization, from individuals to communities. However, it is unclear how color is structured at the intrafloral level. In bee-pollinated flowers, the unidirectional gradient in color purity and pollen mimicry are two common processes to explain intrafloral color patterns. Considering that floral traits are often integrated, usually reflecting evolutionary modules under pollinator-mediated selection, we hypothesize that such intrafloral color patterns are structured by intrafloral color modules as perceived by bee color vision system. Here, we studied the tropical bee-pollinated orchid , given its intrafloral color complexity and variation among individuals. Considering bee color vision, we investigated if intrafloral color modules arose among intrafloral patches (tip or base of the sepals, petals, and labellum). We expected a separate color module between the labellum patches (the main attractive structure in orchids) and petals and sepals. We measured the color reflectance and calculated the photoreceptor excitation, spectral purity, hue, and the chromatic contrast of the floral structures in the hexagon color model. Spectral purity (saturation) was higher in the labellum tip in comparison to petals and sepals, generating a unidirectional gradient. Labellum base presented a less saturated yellow UV-absorbing color, which may reflect a pollen mimicry strategy. presented three intrafloral color modules corresponding to the color of petals and sepals, the color of the labellum tip, and the color of labellum base. These color modules were unrelated to the development of floral structures. Given the importance of intrafloral color patterns in bee attraction and guidance, our results suggest that intrafloral patterns could be the outcome of evolutionary color modularization under pollinator-mediated selection.
人们已经从个体到群落等不同生态组织层次对花色进行了研究。然而，花色在花内水平上是如何构建的尚不清楚。在蜜蜂传粉的花朵中，颜色纯度的单向梯度和花粉拟态是解释花内颜色模式的两个常见过程。鉴于花部性状通常是整合的，通常反映了传粉者介导选择下的进化模块，我们假设这种花内颜色模式是由蜜蜂颜色视觉系统所感知的花内颜色模块构建而成的。在这里，我们研究了热带蜜蜂传粉的兰花，因为其花内颜色复杂且个体间存在差异。考虑到蜜蜂的颜色视觉，我们研究了花内斑块（萼片、花瓣和唇瓣的尖端或基部）之间是否出现了花内颜色模块。我们预计唇瓣斑块（兰花中的主要吸引结构）与花瓣和萼片之间会有一个单独的颜色模块。我们测量了颜色反射率，并计算了六边形颜色模型中花部结构的光感受器激发、光谱纯度、色调和色度对比度。与花瓣和萼片相比，唇瓣尖端的光谱纯度（饱和度）更高，形成了一个单向梯度。唇瓣基部呈现出一种饱和度较低的吸收紫外线的黄色，这可能反映了一种花粉拟态策略。出现了三个花内颜色模块，分别对应花瓣和萼片的颜色、唇瓣尖端的颜色和唇瓣基部的颜色。这些颜色模块与花部结构的发育无关。鉴于花内颜色模式在吸引和引导蜜蜂方面的重要性，我们的结果表明，花内模式可能是传粉者介导选择下进化颜色模块化的结果。
