The mean and variability of a floral trait have opposing effects on fitness traits
The mean and variability of a floral trait have opposing effects on fitness traits
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DOI：
10.1093/aob/mcv189
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发表时间：
2016-03-01
期刊：
影响因子：
4.2
通讯作者：
Galloway, Laura F.
中科院分区：
文献类型：
--
作者：
Dai, Can;Liang, Xijian;Galloway, Laura F.
背景与目的花性状是开花植物成功授粉和繁殖的关键。花柱和花药位置是授粉准确性和效率的关键。这些性状在个体之间的变异已经得到了很好的研究，但对花和植物内部的变异及其对授粉和繁殖成功的影响知之甚少。方法花柱偏转是西番莲雌雄杂交的主要原因，也是花粉沉积的重要原因。挠曲的程度在花内柱头之间和花间都可能不同。我们在花和植物水平上测量了花柱偏转的可变性。在自然授粉条件下，通过结构方程模型确定花柱偏度均值和变异与花粉沉积、种子产量和平均种子重的关系，评估了花柱偏度均值和变异的适应度结果。此外，在温室试验中估计了花柱弯曲与自花花粉沉积的关系。我们发现花柱偏转在花和植物内部的变异比在植物之间的变异更大。花柱偏转的变异在花和植株水平上呈显著正相关，表明花柱偏转的变异可能是白杨的一个显著特征。偏度的降低和偏度变异的减小增加了花粉沉积，从而增加了种子数量。然而，低花柱也增加了自交花粉的沉积。相反，更高的偏转和更大的偏转变异性增加了花粉沉积的变异，从而导致更重的种子。结论花柱偏转的可变性和柱头位置的可变性，独立于平均值，似乎是单个incarnata植物的特性。花柱偏转的平均值和变异率通过花粉沉积的数量和潜在质量以不同的方式影响种子数量和种子重量。这种拮抗选择通过不同的适合度成分可能保持不同的风格表型。
Background and Aims Floral traits are essential for ensuring successful pollination and reproduction in flowering plants. In particular, style and anther positions are key for pollination accuracy and efficiency. Variation in these traits among individuals has been well studied, but less is known about variation within flowers and plants and its effect on pollination and reproductive success.Methods Style deflexion is responsible for herkogamy and important for pollen deposition in Passiflora incarnata. The degree of deflexion may vary among stigmas within flowers as well as among flowers. We measured the variability of style deflexion at both the flower and the plant level. The fitness consequences of the mean and variation of style deflexion were then evaluated under natural pollination by determining their relationship to pollen deposition, seed production and average seed weight using structural equation modelling. In addition, the relationship between style deflexion and self-pollen deposition was estimated in a greenhouse experiment.Key Results We found greater variation in style deflexion within flowers and plants than among plants. Variation of style deflexion at the flower and plant level was positively correlated, suggesting that variability in style deflexion may be a distinct trait in P. incarnata. Lower deflexion and reduced variation in that deflexion increased pollen deposition, which in turn increased seed number. However, lower styles also increased self-pollen deposition. In contrast, higher deflexion and greater variability of that deflexion increased variation in pollen deposition, which resulted in heavier seeds.Conclusions Variability of style deflexion and therefore stigma placement, independent from the mean, appears to be a property of individual P. incarnata plants. The mean and variability of style deflexion in P. incarnata affected seed number and seed weight in contrasting ways, through the quantity and potentially quality of pollen deposition. This antagonistic selection via different fitness components may maintain diverse style phenotypes.