多齿马先蒿与刺齿马先蒿花部形态、昆虫访花频率及种子产量比较研究

Comparative Study on Flower Trait,Pollinator Visitation Rate and Seed Production of Two Pedicularis Species

若尔盖高原的马先蒿属植物花部形态多样化,为探讨花冠差异是否与不同的繁殖对策相联系,在该区四川红原县分别对短管无喙的多齿马先蒿(Pedicularis polyodonta)和长管具喙的刺齿马先蒿(P.armata)的花部形态、昆虫访花频率和种子产出进行了比较研究.多齿马先蒿的花冠呈"鸟头"状,多个花的集合与鸟群相似,因此特别检测了这种拟态是否具有规避鸟类和蝗虫或吸引蜂类传粉的功能.研究发现,与刺齿马先蒿相比,多齿马先蒿的花冠较小、数量较少,但花蜜含量较高,因此蜂类访问频率较高,结实率高.两种马先蒿的单花种子产量没有显著差异;多齿马先蒿单个个体的种子数量较多,但种子较小.研究表明,为提高繁殖成功率,多齿马先蒿倾向于依赖花质量(如花蜜含量所指示)和种子数量,而刺齿马先蒿倾向于依赖花数量.蝗虫对两种马先蒿的危害没有显著差异,说明多齿马先蒿的"鸟头"拟态不具有规避蝗虫的功能;在具有"鸟头"花冠的多齿马先蒿的样地,鸟类的拜访频率较刺齿马先蒿显著较少,但蜂类的访问频率显著较高,说明"鸟头"拟态可能与规避鸟类、保护传粉者有关,其拟态功能需要进一步实验验证.

Pedicularis species display high variation in their flower sizes and shapes on alpine meadows. In order to explore whether the flower morphologies are associated with their reproductive strategies among the species, and to test whether the mimicry functioned to avoid birds and/or herbivore visit and attract insect pollinators, flower trait, nectar volume, pollinator visitation rate, and seed output were investigated for a short-tubed, toothed species （Pedicularis polyodonta） and a long-tube, beaked species （P. armata） on Zoige Plateau, Sichuan, China. In particular, flowers of the former species have bird head-like corollas, making the plants look like a flock of birds foraging on ground, and appearing to be a type of mimicry. It was found that P. polyodonta had fewer and smaller flowers with a larger volume of nectar, and its flowers were more frequently visited by bees and with more fruit set. P. polyodonta had more and smaller seeds than did P. armata. However, the two Pedicularis species did not differ in seed output per flower, suggesting that the reproductive successes of P. polyodonta and P. armata are primarily dependent upon flower quality （as indicated by nectar volume） and quantity （as indicated by flower number per individual）, respectively. In addition, there was no significant difference in locusts＇ feeding preference between P. polyodonta populations with or without the bird head-like corollars, suggesting that the mimicry did not prevent insect herbivores. Bird visitation rate was higher, but bee visitation rate was lower in P. armata than P. polyodonta stands, suggesting that the mimicry might be helpful to attracting bees but preventing birds visit. Fig 2, Tab 1, Ref37