毛地黄鼠尾草在不同授粉条件下的繁殖成功与花性状选择

开花植物的繁殖成功在自然种群普遍受到花粉限制的影响。选择理论认为，当植物种群内不同个体的花粉限制程度存在差异时，将发生传粉者介导的自然选择。通过比较毛地黄鼠尾草在不同授粉条件下的繁殖成功和花性状选择，探究了该植物花表型的适应性及其选择机理。结果表明：1）在自然授粉条件下，该植物的繁殖效率（即坐果率和结籽率）与个体的花柱头高度存在显著的负相关关系（P<0.05），而在人工补充授粉条件下，其繁殖效率与个体的花数量之间存在显著的负相关关系，同时个体的结籽率与柱头探出花冠长度也存在显著的负相关性（P=0.031）。2）在自然授粉条件下，该植物因花粉限制导致的结籽率折损与个体的花数量和柱头探出花冠长度皆存在显著的负相关关系（P=0.006，0.041）。3）在两种授粉条件下，花产量性状均受到显著的定向选择作用，且在人工补充授粉条件下的选择强度显著低于自然授粉状态。花柱头高度仅在自然授粉条件下检测到显著的定向选择，相反，柱头探出花冠长度仅在人工补充授粉条件下检测到显著的定向选择；另外，花冠口大小与柱头探出花冠长度的组合性状受到了显著的相关选择。研究表明，毛地黄鼠尾草的花性状明显受到传粉者介导选择；其中，花部结构性状为提高传粉效率表现出明显的功能整合趋向。

Reproductive success and phenotypic selection on floral traits of Salvia digitaloides under different pollination conditions

The reproduction of plants is generally pollen-limited in natural populations. The theory of phenotypic selection suggests that pollinator-mediated selection occurs when the degree of pollen limitation varies among individuals within a plant population. In this study， we explored aspects of floral adaptation and selection mechanisms in Salvia digitaloides by comparing the differences in reproductive success and selection of floral traits under different pollination conditions. The main results were as follows： 1） The reproductive efficiency of plants （i.e.， fruit set and number of seeds set per flower） was significantly negatively correlated with the height of the stigma in flowers under open pollination （P<0.05）， but significantly negatively correlated with flower production under supplementary hand pollination. The number of seeds set per flower was negatively correlated with style exsertion under supplementary hand pollination （P=0.031）. 2） The extent of the decrease in the number of seeds set per flower due to pollen limitation under open pollination was negatively correlated with both flower production and style exsertion （P=0.006， 0.041）. 3） Under both open and supplementary hand pollination， flower production was subject to significant directional selection， but the selection intensity was much lower under supplementary hand pollination than under open pollination. There was significant negative directional selection for stigma height under open pollination， and for style exsertion under supplementary hand pollination. There was positive correlational selection for the combination of corolla entrance size and style exsertion. Together， the results show that the floral traits of S. digitaloides are subject to significant pollinator-mediated selection， with the floral structural traits showing a trend of functional integration for the improvement of pollination efficiency.