放养蜜蜂对高寒草甸主要蜜源植物花部特征的影响

Plants have evolved many different traits for attracting pollinating animals (e.g., floral size, shape, color, number, and nectar production and olfactory cues). Likewise, pollinators have evolved morphological and behavioral adaptations to maximize their net rate of energy intake while foraging. Previous studies showed that it would be disrupt due to changes in each partner in plant-pollinator relationships. Since 1980 s, a larger number of domesticated honeybees (Apis mellifera) colonies have been introduced to the Zoige Plateau to collect nectar and pollen. Apiculture locally increases plant fitness by providing pollination service. . We hypothesize that intensive apiculture would favor plants visited by domesticated honeybees changing floral features, which would allow plants to reduce attraction of pollinators, and favor plants unvisited by domesticated honey bees changing floral features, which would allow plants to increase attraction of pollinators. In light of this perspective, we will conduct field investigation, common garden experiment and population genetic analyses in alpine meadow on the Zoige Plateau. We specifically aim (1) to clear the effect of domesticated honeybees on floral feature (focus on nectar production, floral size, floral shape, floral color, floral spur length and floral tube length) through investigating the differences of the floral features between sites close and distant to apiaries; (2) to determine the effect of domesticated honeybees on the mutual adaptation between the nectar-producing plants and flower-visiting insects and to illustrate the potential effect of apiculture on the study ecosystem.

植物的花部特征与传粉者的形态结构、行为和多度存在密切的协同进化关系。植物-传粉者组合中某一因素发生改变，都有可能打破原有的协同进化关系。大规模放养蜜蜂能显著增加其传粉植物的传粉量，提高适合度，我们推测：1）放养蜜蜂可能导致这些植物在不影响适合度的情况下，花部特征向降低传粉吸引力的方向改变。同时，放养蜜蜂能降低本土传粉者多度，减小依赖本土传粉者植物的适合度，我们推测：2）放养蜜蜂可能导致依赖本土传粉者的植物为了维持适合度，花部特征向提高传粉吸引力的方向改变。为验证这两种假说，在放养蜜蜂强度大、历史久的若尔盖高寒草甸，项目组将对放养蜜蜂区域和非放养蜜蜂区域内几种主要蜜源植物进行野外调查，结合同质园试验和分子遗传学试验，分析放养蜜蜂对蜜源植物花部特征(重点考虑花蜜量、花形态、花色、花距和花管长度等)和适合度的影响，研究结果将阐明放养蜜蜂介导的动植物相互作用，揭示放养蜜蜂的生态效应和物种适应策略。

近些年来，自然或是人为干扰对植物-传粉者相互作用的影响引起人们的普遍关注。大量的放养蜜蜂作为传粉者进入青藏高原高寒草甸，对当地的蜜源植物传粉综合性状产生强烈的选择压力。本项目重点针对蜜源植物花部特征进行研究，目的是验证不同的植物类型是否采取了不同的适应性变化模式。研究结果表明：1）长期的放养蜜蜂促使蜜蜂大量访问的植物减少花蜜和花粉产量，降低对传粉者的吸引力。另一方面，非蜜蜂传粉的植物则依靠提高花蜜和花粉产量，增加对本土传粉者的吸引力；2）蜜蜂大量访问的植物具有更高的地上部生物量和种子产量，而非蜜蜂传粉的植物趋势相反；3）放养蜜蜂的进入，植物通过平衡繁殖成本与生存成本，以维持或是获取更高植物适合度。蜜蜂大量访问的植物通过减少传粉投资，将资源重新分配到其它部位获得更高的适合度，而非蜜蜂访问的植物则需增加传粉投资，额外的投资导致其适合度的降低。同样的选择压力下，不同植物类型采取了不同的适应性变化模式，研究结果有助于深入理解植物-传粉者种间关系维持与进化。