高山物种栗色鼠尾草(Salvia castanea Diels)访花昆虫多样性与传粉行为变化

唇形科鼠尾草属是世界性分布、物种多样性丰富的大类群，具有独特的传粉模式和多样化的生态类型及繁殖策略，以往对鼠尾草属的花结构和雄蕊杠杆的生态功能、雄蕊杠杆机制对传粉者空间变异的进化响应和表型选择等方面已有较深入的研究，但至今对分布于不同区系代表性物种的传粉者组成、访花行为和繁育系统特征仍知之甚少。对分布于喜马拉雅东段至横断山高海拔地区栗色鼠尾草的传粉生态、交配系统和繁殖特性进行了研究，分析了2014年至2016年的年际间、2014年晴天和阴雨天的传粉者组成和传粉行为变化，探讨了这些变化对繁殖成功的影响。研究结果表明：3年共发现栗色鼠尾草有9种访花昆虫，传粉者组成及其行为变化较为明显。2014年有桔尾熊蜂Bombus friseanus、灰熊蜂B.grahami、圣熊蜂B.religiosus和中华蜜蜂Apis cerana 4种有效传昆虫，2015年仅有桔尾熊蜂是有效传粉者，而2016年的有效传粉昆虫改变为灰熊蜂和圣熊蜂。栗色鼠尾草的盗蜜现象较为普遍，主要盗蜜昆虫为灰熊蜂和桔尾熊蜂。桔尾熊蜂访花行为的年际变化较大，受天气条件的影响明显，同时其有效传粉行为可能显著影响了灰熊蜂的盗蜜行为。栗色鼠尾草的繁育系统为专性异交，主要依靠传粉者进行授粉，缺少传粉者时低程度的主动自花授粉可为其提供繁殖保障，且没有花粉限制和近交衰退。研究揭示了在高海拔地区，多变的天气条件可能显著影响着鼠尾草属植物的传粉者种类组成、访花行为和传粉效率，进而影响植物的繁殖成效和种群稳定。有效传粉频率是保证栗色鼠尾草较高自然结实率的主要因素，在一定程度上，盗蜜强度对繁殖成功具有中性的影响。本研究结果为阐明高山鼠尾草物种的繁殖如何受气候环境变化的影响，以及保证繁殖成功的可能策略奠定基础。

Diversity of visiting insects and changes of pollinator behavior in alpine species Salvia castanea Diels (Lamiaceae)

Salvia L. (Lamiaceae) is a worldwide genus with rich species diversity, a variety of habitat types and unique pollination mode. Previous studies have focused on flower structure and ecological function of stamen lever mechanism, the evolutionary response of stamen lever mechanism to spatial variation in pollinators and phenotypic selection of Salvia. However, the pollinator''s compositions, behavior and reproductive success of representative Salvia species distributed in different flora have been rarely studied. We studied the pollination ecology, breeding system and reproductive characteristics of Salvia castanea, which is widely distributed from the eastern Himalayas to the Hengduan Mountains, we analyzed the composition of pollinators and the interannual changes of pollinator behavior from 2014 to 2016, the daily changes between sunny and rainy days in 2014, and discussed their effects on the reproduction. The results showed that a total of 9 species of visiting insects were found in Salvia castanea during three years and the change of pollinator''s composition and their behavior was obvious. In 2014, S. castanea was legitimately visited by four species including Bombus friseanus, B. grahami, B. religiosus, and Apis cerana. In 2015, the pollinators were reduced to only one species, B. friseanus, however, in 2016, there were two legitimate pollinators, B. grahami and B. religiosus. The nectar robbery is common in S. castanea, and the main robbers are B. grahami and B. friseanus. We found that visiting behavior of B. friseanus showed inter-annual variation and was largely affected by climate, while the nectar robbery of B. grahami probably was affected by activities of B. friseanus. The breeding system for S. castanea was obligate outcrossing, which mainly depended on pollinators for seed set. In the absence of pollinators, low degree of autonomous selfing can provide reproductive assurance for S. castanea, and there was no pollen-limitation and inbreeding depression. Our results revealed that in alpine regions, climate was changeable and weather conditions significantly affected composition of pollinators visit behavior and pollination efficiency, which might, in turn affect reproductive success and population stability of plants. Legitimately, visitation rate is the main factor for ensuring high seed set of S. castanea in open pollination condition, and nectar robbery could maintain a neutral effect on reproductive success at a certain level. Our results of this study provide valuable insights for illustrating how the reproduction of alpine Salvia species is affected by climate and environmental changes and reproductive strategies to ensure reproductive success.