Arroyo Juan, Dafni Amots
Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, 41080 Sevilla, Spain.
Institute of Evolution, University of Haifa, Haifa 31905, Israel.
New Phytol. 1995 Jan;129(1):135-145. doi: 10.1111/j.1469-8137.1995.tb03017.x.
Narcissus tazetta shows a genetically-based discrete polymorphism for style length similar to that well known in heterostylous plants. Plants are either short- (S) or long-styled (1). In Israel, marsh populations are dominated by S plants and hill populations by L plants. Populations differ in size, flowering time and duration, flower orientation, inflorescence display, vegetative reproduction, and pollinators. The main visitors to flowers in marshes are hawkmoths, whereas in the hills they are visited by short-tongued insects: solitary bees and hoverflies. The pollination efficiency of these insects was investigated by studying foraging behaviour, visit rate, and pollen deposition on stigmas. Our findings are consistent with the hypothesis of lower efficiency of pollination of S flowers by short-tongued insects, resulting in the exclusion of this morph from the hills. Additionally, we considered the possibility that there might be pollination ecotypes corresponding to the two habitats (marsh and hill) and examined variation in a set of continuous flower traits related to pollination biology. Flower tube length was the only trait showing a distinct difference between the two habitat types. Although the concentration of nectar was not different between habitats, L flowers presented more concentrated nectar than S flowers. Such a difference in nectar concentration may he of adaptive value for the pollination of the L flowers by short-tongued pollinators in the hills.
水仙呈现出一种基于遗传的花柱长度离散多态性，类似于在异型花柱植物中广为人知的那种。植株要么是短花柱（S）型，要么是长花柱（L）型。在以色列，沼泽种群以S型植株为主，而山地种群以L型植株为主。不同种群在大小、开花时间和持续时间、花朵朝向、花序展示、营养繁殖以及传粉者等方面存在差异。沼泽中花朵的主要访客是天蛾，而在山地，花朵则由短舌昆虫光顾：独居蜂和食蚜蝇。通过研究这些昆虫的觅食行为、访花率以及花粉在柱头上的沉积情况，对它们的传粉效率进行了调查。我们的研究结果与短舌昆虫对S型花朵传粉效率较低的假设一致，这导致这种形态在山地被排除。此外，我们考虑了可能存在与两种栖息地（沼泽和山地）相对应的传粉生态型，并研究了一组与传粉生物学相关的连续花朵性状的变异情况。花管长度是唯一在两种栖息地类型之间表现出明显差异的性状。虽然不同栖息地之间花蜜浓度没有差异，但L型花朵的花蜜比S型花朵的花蜜更浓缩。这种花蜜浓度的差异可能对山地中短舌传粉者对L型花朵的传粉具有适应性价值。
