Continuous variation in herkogamy enhances the reproductive response of Lonicera implexa to spatial variation in pollinator assemblages
Continuous variation in herkogamy enhances the reproductive response of Lonicera implexa to spatial variation in pollinator assemblages
复制标题
两性受精的连续变化增强了忍冬对传粉者组合空间变化的生殖反应
作者：
A. Lázaro;J. Seguí;L. Santamaría
摘要 雌雄同体植物中性器官的空间分离，已被认为是减少自花授粉以及相关的近交和配子浪费过程的机制。纵向雌花受精是最常见的类型，有两种亚型：接近雌花受精（柱头下方的花药）与不同的传粉昆虫阵列相关，以及反向雌花受精（柱头上方的花药）与专门的长舌传粉昆虫相关。通过使用从负值（反向雌雄配体）到正值（接近雌雄配体）连续变化的雌雄受精指数，我们研究了雌雄同性的连续变化对长舌传粉者与短舌传粉者相对丰度不同的三个金银花群体的传粉者吸引力、自交能力和植物适应性的影响。在长舌传粉媒介占主导地位的种群中，反向雌雄受精的发生率明显高于其他两个种群。与此一致的是，具有小和大雌雄受精指数的 L. implexa 个体的主要花香访客分别是长舌和短舌传粉者。自发自交较低，并且随着雌雄受精指数的增加（即接近雌雄受精）而增加，尽管大多数发生在花药和柱头之间距离较近时。在长舌传粉媒介的种群中，果实产量与受精指数无关，但在其他两个种群中，果实产量随着接近受精指数（较高的受精指数）而增加。相比之下，具有反向雌雄配体（雌雄配体指数较小）的个体的种子发芽得更好。在这个物种中，两性受精的持续变异可能起到一种繁殖策略的作用，因为不同的形态类型可能受到不同传粉者组合的青睐。
Abstract Herkogamy, the spatial separation of sex organs in hermaphroditic plants, has been proposed as a mechanism to reduce self-pollination and the associated processes of inbreeding and gamete wastage. Longitudinal herkogamy is the most frequent type, with two subtypes: approach herkogamy (anthers below the stigma), which is associated with diverse pollinator arrays, and reverse herkogamy (anthers above the stigma), associated with specialized, long-tongued pollinators. By using a herkogamy index that varied continuously from negative (reverse herkogamy) to positive (approach herkogamy) values, we studied the effect of continuous variation in herkogamy on pollinator attraction, selfing capability and plant fitness across three populations of Lonicera implexa differing in the relative abundance of long-tongued vs. short-tongued pollinators. Reverse herkogamy was significantly more frequent in the population where long-tongued pollinators were dominant than in the other two populations. Agreeing with this, the main floral visitors of L. implexa individuals with small and large herkogamy index were, respectively, long-tongued and short-tongued pollinators. Spontaneous selfing was low and increased with increasing herkogamy index (i.e. with approach herkogamy), although most of it occurred when there was close distance between anthers and stigma. Fruit production was unrelated to the herkogamy index in the population with long-tongued pollinators, but it increased with approach herkogamy (higher herkogamy index) in the other two populations. In contrast, seeds of individuals with reverse herkogamy (smaller herkogamy indices) germinated better. In this species, continuous variation in herkogamy might function as a reproductive strategy, as different morphotypes might be favoured by different pollinator assemblages.