Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Sevilla, Spain.
Ann Bot. 2013 Feb;111(2):317-28. doi: 10.1093/aob/mcs261. Epub 2012 Dec 5.
Heterostyly and related style polymorphisms are suitable model systems to evaluate the importance of functional pollinators in the maintenance of population variability. In Narcissus papyraceus different functional pollinators, incompatibility system and flower morphology have been proposed to influence the maintenance of polymorphism through their effect on disassortative mating. Here a test is done to find out if the visitation rate of long- versus short-tongued pollinators correlates with the morph ratio and if the latter is related to other flower traits of the species across its main geographic range.
Floral traits from 34 populations in the south-west of the Iberian Peninsula and in north-west Africa were measured, perianth variation was described and a comparison was made of allometric relationships between sex organs and floral tube. Correlations between pollinator guilds, stigma-anther separation of reciprocal morphs (our proxy for disassortative mating) and morph-ratio variation were analysed. Finally, the incompatibility system of the species in the northern and southern borders of its distribution are described.
Flowers from southern populations were significantly larger than flowers from centre and northern populations. The abundance of short-styled plants decreased gradually with increasing distance from the core region (the Strait of Gibraltar), with these disappearing only in the northern range. Although there was a significant difference in stigma-anther separation among populations, morph ratio was not associated with reciprocity or floral tube length. Long-style morph frequency increased with short-tongued pollinator visitation rate. Populations from both edges of the distribution range were self-incompatible and within- and between-morph compatible.
The style morph ratio changed gradually, whereas perianth trait variation showed abrupt changes with two morphotypes across the range. The positive relationship between the visitation rate of short-tongued pollinators and the decrease of the short-style morph supports our initial hypothesis. The results highlight the importance of different pollinators in determining the presence of style polymorphism.
异型花柱和相关的柱头形态多态性是评估功能传粉者在维持种群变异性中的重要性的合适模型系统。在多花水仙中，不同的功能传粉者、不亲和系统和花形态被认为通过其对异质交配的影响来影响多态性的维持。在这里，我们进行了一项测试，以确定长舌和短舌传粉者的访问率是否与形态比相关，以及后者是否与物种在其主要地理分布范围内的其他花特征相关。
在伊比利亚半岛西南部和北非的 34 个种群中测量了花的特征，描述了花被片的变化，并比较了雌雄器官和花管之间的异速关系。分析了传粉者群体、互交异型柱头-花药分离（我们异质交配的替代指标）和形态比变化之间的相关性。最后，描述了该物种在分布区北部和南部边界的不亲和系统。
来自南部种群的花明显大于来自中心和北部种群的花。短花柱植物的丰度随着与核心区域（直布罗陀海峡）的距离的增加而逐渐减少，在北部范围消失。尽管种群之间的柱头-花药分离存在显著差异，但形态比与互交或花管长度无关。长花柱形态的频率随着短舌传粉者访问率的增加而增加。分布范围边缘的种群均为自交不亲和，同种异型之间和异型之间均为亲和。
花柱形态比逐渐变化，而花被片特征的变化在整个范围内突然出现两种形态类型。短舌传粉者访问率与短花柱形态减少之间的正相关关系支持了我们的初始假设。研究结果强调了不同传粉者在决定花柱多态性存在方面的重要性。
