花寿命的进化生态学意义

REVIEW OF EVOLUTIONARY ECOLOGY OF FLORAL LONGEVITY

花寿命(Floral longevity)是指一朵花保持开放并具有功能的持续时间,它作为一种重要的繁殖策略影响着植物的繁殖,在植物繁殖策略的进化生态学研究中具有非常重要的意义。近年来,进化生态学家开始重视花寿命的研究,在传粉与非传粉因素对花寿命的影响、花展示和繁殖成功与花寿命的关系等方面取得了长足的进展。生活史进化模型表明,最优花寿命取决于开花成本和两性适合度实现速率之间的权衡。大量的实验研究支持此模型。实验研究表明:授粉可导致某些植物的花寿命显著缩短,但是,花粉移除对花寿命一般没有显著影响;部分植物的花具有最短花寿命,这可能是一种保证植物雄性适合度的机制;温度和水分等非传粉因素的变化,因改变开花成本而影响到花寿命;在花的群体水平上,植物根据传粉状况和资源状况,会调节花序上不同花的开放时间,进而改变花展示的结构和功能;长的花寿命是保障植物繁殖成功的重要机制之一,但可能要付出一定的适合度代价。该文概述了花寿命进化生态学的理论和实验研究进展,最后指出:在理论研究上,雌雄利益冲突为理解花寿命的进化提供了新的视角。在实验研究中,需要重视植物通过优化花寿命而增强雄性适合度的研究思路。对花寿命的成本-收益分析,需要考虑单花与花展示的功能关系。

Floral longevity, the length of time that a flower remains open and functional, is an important floral trait that influences plant reproductive success. Recently, there has been a large increase in research on floral longevity. Many advances have enriched our understanding of evolution and ecology of floral longevity. These studies focused on the effects of both pollination and non-pollination factors on variation of duration of flower anthesis, interactions between floral longevity and floral display, and relationships between floral longevity and reproductive assurance. However, no review has been available on these developments. We briefly summarize the development of theoretical studies on floral longevity and review the progress of empirical studies. The life history evolutionary theoretical mode suggested floral longevity was determined by costs of maintaining flowers and the fitness accrual rate, which was supported by many empirical studies. Experimental studies demonstrated that flower senescence is advanced by deposition of pollen grains on the stigma but pollen removal does not significantly affect floral duration. Some of these plants have a minimum longevity during which the flower never abscises. Environmental factors, such as temperature and water availability or humidity, can change costs of maintaining flowers and then change floral longevity. Because of the costbenefit of floral display, plants often adjust floral longevity to alter display size. Floral longevity also can adjust according to resource allocation. Long floral duration can provide reproductive assurance, but may suffer some fitness costs. Although progress has been made, many questions remain and we propose new ideas. For theoretical studies, male and female conflict provides a new perspective to understand the evolution of floral longevity. For empirical studies, we suggestthat evolutionary biologists should pay more attention to male fitness and analyze cost-benefit of floral longevity at the inflorescence level.