青藏高原东缘星状风毛菊生殖分配对海拔的响应

Variation of reproductive allocation along elevations in Saussurea stella on East Qinghai-Xizang Plateau

通过采样调查法和烘干称量法,检测了青藏高原东缘不同海拔20个居群星状风毛菊(Saussurea stella)的花部特征,研究其花部特征对海拔及个体大小的响应。结果表明:1)繁殖分配是依赖个体大小的,个体越大,繁殖分配越小;2)花期繁殖器官和营养器官的生物量、头状花序的数量及大小、雌雄功能以及雄性内部花丝与花粉之间均存在资源分配上的权衡;3)星状风毛菊通过花部特征的变异响应海拔的变化。研究发现,星状风毛菊通过花部特征的变异,特别是花柱和花丝的伸长及投入更多资源于吸引结构花瓣,以此来补偿该种在高海拔地区因传粉者减少、活动频率降低和花粉数减少等因素对传粉带来的影响,使其能够在高海拔的胁迫环境下有效地传粉,完成有性繁殖。

Aims Our objective is to study the variation in floral traits of Saussurea stella in 20 populations in response to elevation and mean plant size on the East Qinghai-Xizang Plateau. Methods We used population means to evaluate sources of variation in reproductive allocation within species. In addition, we used the sample investigation method and dry weight to evaluate biomass. Important findings Reproductive allocation is negatively correlated with mean plant size. There are trade-offs of resource allocation in reproductive biomass and vegetative biomass, capitulum number and its weight, male and female as well as filament and pollen. Additionally, there is a relationship between variation in floral traits of S. stella and elevation. Consequently, the variation of floral traits ensures that S. stella pollinates effectively and completes sexual reproduction.