Data from: Long-tongued insects promote disassortative pollen transfer in style-dimorphic Narcissus papyraceus (Amaryllidaceae)

1. In hermaphroditic flowers, reciprocal herkogamy e.g. heterostyly enhances pollen transfer between floral morphs (disassortative pollination) while avoiding self-interference between sexual organs. By contrast, disassortative pollination might be compromised in style-dimorphic flowers, which lack perfect reciprocity between the two floral morphs. This sub-optimal functioning has been considered to explain why stylar dimorphism is rare in nature. 2. Some style-polymorphic species receive a wide array of floral visitors, including long-tongued insects that feed on nectar and short-tongued insects that feed on pollen. Differences in the morphology and behaviour of these two insect types could be manifested as different pollination patterns in each floral morph. 3. By observing individual pollinators and pollen deposition and delivery in small field-based experimental arrays with emasculated and intact flowers, we studied pollination patterns mediated by different insect types (long- and short-tongued) in the two floral morphs (long- and short-styled) of the style-dimorphic Narcissus papyraceus. We investigated patterns of pollen transfer between and within style morphs in cross pollinations, as well as self-pollination and pollen-removal rates, for each floral morph mediated by each insect type. 4. Long-tongued insects were efficient pollinators of both floral morphs as they removed little pollen from the anthers but deposited comparatively large amounts on the stigmas. Although disassortative and assortative pollen transfer were equally high to the long-styled morph, the former prevailed in the short-styled morph. Short-tongued insects removed large amounts of pollen from the anthers but deposited only a few pollen grains on the long-styled stigmas and a negligible number of grains on short-styled stigmas regardless of the morph of the donor. 5. In this study we provide empirical support for the hypothesis that, under the action of long-tongued pollinators, pollen transfer patterns in the stylar-dimorphic Narcissus papyraceus resemble in part those of heterostylous species. In addition, we found that short-tongued insects act mostly as pollen thieves, thereby limiting the male fitness of both style morphs, besides depleting the female fitness of S-morph plants. In view of these results, we propose that the differing pollination efficiencies of floral visitors, in addition to their frequency, are key in determining the morph ratio of populations in this Narcissus.

1. 在两性花中，交互雌雄异位（reciprocal herkogamy）如花柱异型（heterostyly）可促进花型间的花粉传递（即异型传粉（disassortative pollination）），同时避免两性器官间的自交干扰。相较而言，在缺乏两种花型完美交互匹配的花柱二型花（style-dimorphic flowers）中，异型传粉可能会受到削弱。这种功能欠佳的情况被认为是解释自然界中花柱二型性较为罕见的原因。
2. 部分花柱多型物种会吸引多样的传粉者，包括以花蜜为食的长舌昆虫与以花粉为食的短舌昆虫。这两类昆虫在形态与行为上的差异，可能会在不同花型中体现为不同的传粉模式。
3. 本研究通过在小型野外实验阵列中观察单个传粉者，以及对去雄花（emasculated flowers）与完整花的花粉沉积和传递情况进行监测，针对花柱二型性的纸白水仙（Narcissus papyraceus）的两种花型（长花柱型与短花柱型），探究了不同昆虫类型（长舌昆虫与短舌昆虫）介导的传粉模式。我们针对每种传粉昆虫类型介导下的各花型，调查了异型与同型杂交授粉中的花粉传递模式，同时也分析了自花授粉情况与花粉移除速率。
4. 长舌昆虫是两种花型的高效传粉者：它们从花药（anthers）中移除的花粉量较少，但向柱头（stigmas）上沉积的花粉量相对较多。尽管向长花柱型花的异型与同型花粉传递效率相当，但异型传粉在短花柱型花中占主导地位。短舌昆虫会从花药中移除大量花粉，但仅在长花柱型柱头上沉积少量花粉，且无论花粉供体的花型如何，在短花柱型柱头上沉积的花粉粒都可忽略不计。
5. 本研究为以下假说提供了实证支持：在长舌传粉者的作用下，纸白水仙的花柱二型性花粉传递模式在一定程度上与花柱异型物种相似。此外，我们发现短舌昆虫大多充当花粉窃贼，不仅会耗尽短花柱型植株的雌性适合度（fitness），还会限制两种花柱型的雄性适合度。基于上述结果，我们提出：除传粉者的发生频率外，不同传粉者的传粉效率差异，是决定该水仙种群花型比例的关键因素。