青藏高原高寒草甸植物花寿命对传粉环境的响应

Responses of floral longevity to pollination environments in 11 species from two alpine meadows

花寿命是指花保持开放且具有功能的时间长度。不同物种的花寿命具有显著的差异,但一定程度上的可塑性反映了植物对传粉环境变化的适应性。本研究以青藏高原高寒草甸不同海拔(2,900 m和3,600 m)的11种开花植物为研究对象,通过套袋、补充授粉以及自然授粉处理分别测量了植物的潜在花寿命、最短花寿命以及实际花寿命。分析了不同海拔植物花寿命的变异,以及对套袋处理(潜在花寿命与实际花寿命之差)和补充授粉处理(实际花寿命与最短花寿命之差)的响应及其可塑性(潜在花寿命与最短花寿命之差)的变异。结果表明:无论是高海拔还是低海拔,套袋显著延长了花寿命,而补充授粉显著缩短了花寿命,即,潜在花寿命>实际花寿命>最短花寿命。高海拔群落中植物的实际花寿命和潜在花寿命均显著延长,而最短花寿命在海拔间差异不显著。相对于低海拔群落,高海拔植物的花寿命对补充授粉处理更敏感,花寿命的可塑性更大。本研究说明传粉者稀少的高寒环境中,植物通过提高花寿命及其可塑性来增加授粉机会,获得更高的适合度。

Floral longevity, the length of time that a flower remains open and functional, varies greatly among species. The high plasticity of floral longevity can reflect an adaptation to variable pollination envi- ronments. In the alpine meadows of Qinghai-Tibetan Plateau （2,900 m vs. 3,600 m）, we assessed how potential floral longevity, the shortest floral longevity and the actual floral longevity of 11 species varied under treatments of different pollination contexts. We modeled the response of floral longevity to pollinator exclu- sion （potential floral longevity minus actual floral longevity） and supplemental pollination （actual longevity minus shortest longevity）, and the plasticity of floral longevity （potential longevity minus shortest longevity） at high and low altitude habitats. We found that the plants at the high-altitude community had longer potential floral longevity compared to the low-altitude community, while the shortest floral longevity was not signifi- cantly different. Furthermore, pollinator exclusion significantly increased flower longevity, while supple- mental pollination significantly decreased floral longevity （i.e. the potential floral longevity 〉 the actual floral longevity 〉 the shortest floral longevity） in both high and low-altitude habitats. In comparison with the low-altitude community, high-altitude plants exhibited higher plasticity of floral longevity. Overall, our results suggest that greater plasticity of floral longevity may increase the opportunity for pollination and thus aid fitness at higher altitudes where pollinators are scarce and unpredictable.