Castilla Antonio R, Alonso Conchita, Herrera Carlos M
Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas (CSIC), Avenida Américo Vespucio s/n 41092 Sevilla, Spain
Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas (CSIC), Avenida Américo Vespucio s/n 41092 Sevilla, Spain.
Am J Bot. 2016 Mar;103(3):388-95. doi: 10.3732/ajb.1500167. Epub 2016 Feb 29.
Changes in the pollinator communities of marginal plant populations can affect their pollination quantity or quality. Geographic variation in pollination success can alter the reproductive advantage that female plants require to persist within gynodioecious populations. Particularly valuable is determining the pollination success at the prezygotic stage in self-compatible gynodioecious species whose females do not exhibit enhanced seed production.
In core and marginal populations of Daphne laureola, we analyzed the differences between hermaphrodites and females in the proportion of flowers visited, the stigma pollen loads, and the quantity of pollen tubes in styles. We also examined the relationship between the number of pollen tubes in styles vs. the number of pollen grains on stigmas using piecewise regression and binomial generalized linear mixed models.
Pollinators deposited larger pollen loads on flowers in marginal populations. In marginal populations, female flowers received more pollinator visits and more pollen grains on their stigmas, and they had more pollen tubes in their styles than did female flowers in core populations. Both piecewise regression and binomial GLMM analyses showed that females in marginal populations had a lower proportion of grains that developed tubes than females in the core populations, which suggests decreased pollination quality.
More efficient pollination services in marginal populations decreased the overall differences in the prezygotic pollination success between the sex morphs. Our results also suggest that pollination quality is lower in females of marginal populations, which could be counteracting the increased pollination in females in marginal populations.
边缘植物种群传粉者群落的变化会影响其传粉数量或质量。传粉成功率的地理变异会改变雌株在雌雄异株种群中维持生存所需的繁殖优势。对于确定自交亲和的雌雄异株物种在合子前阶段的传粉成功率尤其有价值，这些物种的雌株并未表现出种子产量的增加。
在月桂瑞香的核心种群和边缘种群中，我们分析了雌雄同株和雌株在花朵被访比例、柱头花粉载量以及花柱中花粉管数量方面的差异。我们还使用分段回归和二项广义线性混合模型研究了花柱中花粉管数量与柱头上花粉粒数量之间的关系。
传粉者在边缘种群的花朵上沉积了更多的花粉载量。在边缘种群中，雌花接受传粉者的访问更多，柱头上的花粉粒更多，并且花柱中的花粉管比核心种群中的雌花更多。分段回归和二项广义线性混合模型分析均表明，边缘种群中的雌株发育出花粉管的花粉粒比例低于核心种群中的雌株，这表明传粉质量下降。
边缘种群中更高效的传粉服务减少了性别形态在合子前传粉成功率上的总体差异。我们的结果还表明，边缘种群中雌株的传粉质量较低，这可能抵消了边缘种群中雌株传粉增加的影响。
