Data from: Ginger and the beetle: Evidence of primitive pollination system in a Himalayan endemic alpine ginger (Roscoea alpina, Zingiberaceae)

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The Himalayan endemic alpine genus Roscoea, like other members of ginger family, exhibits the combination of floral traits that would fit pollination by long distant foragers such as bees, birds or flies. We studied the pollination biology of Roscoea alpina, observed potential floral visitors and determined their foraging behaviour, visitation frequency and pollination efficiency, to seek evidence in support of the pollination syndrome hypothesis. We also measured the floral spectra of R. alpina flowers to evaluate if signals fit with the currently known framework for observed floral visitors. We found that R. alpina have autonomous selfing and pollinator-mediated crossing, but lack apomixis. We observed that a beetle (Mylabris sp.), and a moth (Macroglossum nycteris) visit the flowers of R. alpina for pollen and nectar feeding respectively. Our field observations, the stigmatic pollen count and fruit set data indicated that the visit by the beetle was legitimate, while that of the moth was illegitimate. Emasculated flowers visited by beetles set as many fruits and seeds/fruit as auto-selfed and naturally pollinated flowers, while emasculated flowers excluded from beetle visits did not set fruit and seed; indicating that a single visit of a beetle to the flowers of R. alpina can facilitate pollination. We found that flower spectral signal of R. alpina does not fit typical spectra previously reported for beetle or bee-visited flowers. Our results suggest that, to ensure reproductive success in alpine habitat, R. alpina has evolved autonomous selfing as a predominant mode of reproduction, while beetle pollination would promote genetic diversity of this plant species. The visitation of beetles to the flowers of R. alpina, despite floral signal mismatch with the classically associated beetle vision, suggests that a different visual processing may operate in this plant-pollinator interaction at high altitudes.

附件文件为关联文章提供补充数据集。与姜科其他类群一致，喜马拉雅特有高山属象牙参属（Roscoea）所具备的一系列花部性状，适配于蜂类、鸟类或蝇类等远距离觅食者的传粉模式。本研究以高山象牙参（Roscoea alpina）为对象，探究其传粉生物学特性，记录潜在花部访客、测定其觅食行为、访花频率与传粉效率，旨在为传粉综合征假说提供实证支持。本研究同时测定了高山象牙参的花部光谱特征，以评估其花部信号是否契合当前已知的对应访客的视觉识别框架。研究结果显示，高山象牙参兼具自主自交与传粉者介导的异交，但无无融合生殖现象。本研究观察到，芫菁属（Mylabris sp.）甲虫与夜行长喙天蛾（Macroglossum nycteris）分别以花粉和花蜜为食，造访高山象牙参的花朵。野外观察、柱头花粉计数与坐果率数据均表明，芫菁甲虫的访花行为具有传粉有效性，而天蛾的访花则无传粉功能。去雄后被芫菁甲虫访花的花朵，其坐果率与单果种子数均与自主自交组及自然传粉组花朵无显著差异；而排除芫菁甲虫访花的去雄花朵则完全无法坐果结籽，这表明芫菁甲虫单次访花即可有效介导高山象牙参的传粉过程。本研究发现，高山象牙参的花部光谱信号并不符合此前报道的、适应甲虫或蜂类访花的典型光谱特征。研究结果表明，为保障高山生境中的繁殖成功率，高山象牙参演化出以自主自交为主的繁殖策略，而芫菁甲虫传粉则可促进该物种的遗传多样性。尽管高山象牙参的花部信号与经典认知中甲虫的视觉识别模式并不匹配，但芫菁甲虫仍会造访其花朵，这暗示在高海拔地区的植物-传粉者互作体系中，可能存在一套独特的视觉识别机制。