作 者 ：王一峰, 高宏岩, 施海燕, 王剑虹, 杜国祯
期 刊 ：植物生态学报 2008年 32卷 2期 页码：379-384
Keywords:Saussurea parviflora, sexual organ, altitude variation, Qinghai-Tibetan Plateau,
摘 要 ：小花风毛菊(Saussurea parviflora)是菊科风毛菊属的一种多年生草本植物，是该属在青藏高原东缘的一个优势种。该文研究了小花风毛菊11个居群性器官的变异与11个海拔高度(2 100～3 500 m)之间的相关性，以及花丝、花药长和花柱、花柱分枝长与花粉数之间的相关性；探讨了小花风毛菊的性器官是如何随海拔高度发生变异，如何与胁迫环境相适应，实现交配成功，提高繁殖成功率，使其成为该属植物“现代 分布中心"的优势种。结果表明：1)花丝、花药长与海拔高度呈极显著的正相关关系(p<0.01)；2)花粉数与海拔高度呈极显著的负相关关系(p<0.01)；3)花柱、花柱分枝长及花柱分枝长和雌蕊长的比与海拔高度呈极显著的正相关关系(p<0.01)；4)花柱、花柱分枝长和花丝长与花粉数呈显著的负相关关系(p<0.05)；5)种子的成熟率与海拔高度呈显著的正相关关系(p<0.05)。说明小花风毛菊种内性器官在特定的生存环境下发生了变异，特别是在花粉数随海拔的升高明显减少以及昆虫的多样性、丰富性和活动性明显降低的情况下，它能够通过花柱分枝长度的变异来提高柱头对传粉昆虫的感受性，能通过种子成熟率的提高来保证高海拔数目显著减少的种子的成功发育，进而在一定程度上导致了该物种繁殖成功率的上升，使它成为青藏高原这一胁迫环境中的优势种。
Abstract:Aims Saussurea parviflora is the dominant species on the Qinghai-Tibetan Plateau. This study addresses the following: 1) correlations between S. parviflora’s sexual organs and altitude, 2) correlations among S. parviflora’s sexual organs, and 3) reasons for S. parviflora’s adaptation to this stressful environment.
Methods During the flowering phase in August-September 2005, we collected 11 populations of S. parviflora from different altitudes. We harvested 20 individual s from each population and randomly selected 10 capitula from each individual. We randomly selected 20 flowerlets from different capitula from the same altitude and fixed them in FAA (18∶2∶2, alcohol∶formaldehyde∶glacial acetic acid). We measured the length of sexual organs in 20 fully-opened flowerlets and counted pollen in 10 mature flowerlets with undehisced anthers. At the fruiting stage in October 2005 and 2006, we harvested 10 individuals of each population and randomly selected 200 capitula to count the maturation rate. All experimental data were analyzed with the statistical analysis software SPSS11.5.
Important findings There was a strong positive correlation among filament length, anther length and altitude (p<0.01) and a strong negative correlation between pollen number and altitude (p<0.01). Moreover, there were strong positive correlations among 1) style length, length of style ramification and altitude (p< 0.01 ) and 2) style length, length of style ramification, filament length and anther number (p<0.05), and between maturation rate and altitude (p<0.05). Therefore, variation of intraspecific sexual organs under specific environmental condition made S. parviflora adapted to the Qinghai-Tibetan Plateau. With reduced pollen number and insect diversity, abundance and activity with increased altitude, the style ramification lengthened and maturation rate improved. This enhanced the sensitivity to pollinators, ensuring that the decreased pollen was sufficiently spread by them, resulting in increased success of reproduction and dominance in the stressful environment.
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