Peach Kristen, Liu Jasen W, Klitgaard Kristen N, Mazer Susan J
Department of Ecology, Evolution and Marine Biology University of California, Santa Barbara Santa Barbara CA USA.
Ecol Evol. 2020 Feb 5;10(4):1856-1875. doi: 10.1002/ece3.5987. eCollection 2020 Feb.
●Many angiosperms are hermaphroditic and produce bisexual flowers in which male (pollen export) and female (stigma receptivity) functions are separated temporally. This sequential hermaphroditism may be associated with variation in flower size, color, or pattern, all of which may influence pollinator attraction. In this study, we describe variation in these traits across discrete functional sex stages within and between 225 greenhouse-grown individuals of (Onagraceae). In addition, to identify the effects of floral phenotype on pollinator attraction in this species, we examine the effects of these floral traits on pollen receipt in ~180 individuals in an experimental field array.●Petal area, ultraviolet (UV)-absorbing nectar guide area, and blue and green mean petal reflectance differ significantly across the functional sex stages of . Male- and female-phase flowers display significantly different pollinator attraction traits. Petal and UV nectar guide area increase as flowers progress from male phase to female phase, while blue reflectance and green reflectance peak during anther maturation.●In field arrays of , female-phase flowers with large UV nectar guides receive more pollen than those with small nectar guides, and female-phase flowers with high mean blue reflectance values are more likely to receive pollen than those with low blue reflectance. Female-phase flowers with green mean reflectance values that differ most from background foliage also receive more pollen than those that are more similar to foliage. These findings indicate that components of flower color and pattern influence pollen receipt, independent of other plant attributes that may covary with floral traits. We discuss these results in the context of hypotheses that have been proposed to explain sex-specific floral attraction traits, and we suggest future research that could improve our understanding of sexual dimorphism in sequentially hermaphroditic species and the evolution of features that promote outcrossing.
●许多被子植物是雌雄同体的，会产生两性花，其中雄性（花粉输出）和雌性（柱头可接受性）功能在时间上是分开的。这种顺序性雌雄同体可能与花的大小、颜色或图案的变化有关，所有这些都可能影响传粉者的吸引力。在本研究中，我们描述了在225株温室种植的柳叶菜科月见草属植物个体内部和之间，这些性状在不同的功能性性别阶段的变化。此外，为了确定该物种花表型对传粉者吸引力的影响，我们在一个实验性田间阵列中，研究了这些花性状对约180个个体花粉接收的影响。●月见草属植物的花瓣面积、吸收紫外线（UV）的花蜜引导区以及蓝色和绿色花瓣平均反射率在不同的功能性性别阶段存在显著差异。雄性阶段和雌性阶段的花表现出显著不同的传粉者吸引性状。随着花从雄性阶段发展到雌性阶段，花瓣和UV花蜜引导区会增大，而蓝色反射率和绿色反射率在花药成熟时达到峰值。●在月见草属植物的田间阵列中，具有大的UV花蜜引导区的雌性阶段花比具有小花蜜引导区的花接收更多花粉，并且具有高平均蓝色反射率值的雌性阶段花比具有低蓝色反射率的花更有可能接收花粉。与背景叶子颜色差异最大的具有绿色平均反射率值的雌性阶段花也比那些与叶子更相似的花接收更多花粉。这些发现表明，花的颜色和图案成分会影响花粉接收，独立于可能与花性状相关的其他植物属性。我们在已提出的解释性别特异性花吸引性状的假设背景下讨论这些结果，并建议未来的研究可以增进我们对顺序性雌雄同体物种中性别二态性以及促进异交特征进化的理解。
