Institut Mediterrani d'Estudis Avançats, IMEDEA (CSIC-UIB), Miquel Marqués 21, Esporles, 07190 Mallorca, Balearic Islands, Spain.
J Plant Res. 2011 Mar;124(2):277-87. doi: 10.1007/s10265-010-0373-y. Epub 2010 Sep 4.
Taxonomically related species can differ in a number of reproductive traits, which may translate into a differential mating system and pollination success. Here we compare two hermaphroditic insect-pollinated Daphne species (D. rodriguezii and D. gnidium) which differ in distribution (island endemic vs. mediterranean) and floral traits (long- vs. short-tube corolla). We investigated their mating system and pollen limitation by means of hand-pollination experiments and quantified the diversity and abundance of flower visitors by direct observations. Plant size and five reproductive traits (flower production, proportion of viable anthers, pollen production, flower tube length and tepal area) were studied to assess how they contribute to reproductive success, measured as proportion of pollen grains germinated per stigma and fruit set. Selfing was very low and pollen limitation existed in both species, though was higher in D. rodriguezii probably due to the scarcity of flower visitors. The low fruit set in both species suggests that most of the pollen grains found on stigmas are self-pollen. Pollinators appeared to favour some floral traits (specifically, flower tube length or tepal area) in both species, although flower crop in D. rodriguezii was the only reproductive trait influencing fruit set. In both species, the highest variability in reproductive traits and pollination success was within individuals. Our findings suggest that despite both species showed similar mating system, dependency on outcrossing pollen and selection of floral traits, pollen limitation was higher in D. rodriguezii, probably as a higher proportion of self-pollen arrives to its stigmas.
分类上相关的物种在许多繁殖特征上可能存在差异，这些差异可能导致不同的交配系统和授粉成功率。在这里，我们比较了两种雌雄同体的昆虫授粉的瑞香属植物（D. rodriguezii 和 D. gnidium），它们在分布（岛屿特有种与地中海种）和花部特征（长筒花冠与短筒花冠）上存在差异。我们通过人工授粉实验比较了它们的交配系统和花粉限制，并通过直接观察量化了访花者的多样性和丰度。我们研究了植株大小和五个繁殖特征（花产量、可育花药比例、花粉产量、花管长度和花瓣面积），以评估它们对生殖成功的贡献，生殖成功以每个柱头的花粉粒萌发率和结实率来衡量。自交率非常低，两种植物都存在花粉限制，但 D. rodriguezii 中的花粉限制更高，可能是由于访花者稀少。两种植物的结实率都较低，这表明大多数落在柱头上的花粉粒都是自花粉。传粉者似乎偏爱某些花部特征（特别是花管长度或花瓣面积），尽管在 D. rodriguezii 中花产量是唯一影响结实率的繁殖特征。在两种植物中，个体内繁殖特征和授粉成功率的变异性最大。我们的研究结果表明，尽管两种植物的交配系统相似，依赖异交花粉和选择花部特征，但 D. rodriguezii 中的花粉限制更高，可能是因为更多的自花粉到达它的柱头。
