展毛翠雀的花性状表型选择

传粉者的选择作用是花表型性状进化的重要驱动力, 解析选择作用的强度是理解花进化的关键。通过表型操控实验和表型选择研究能够分析花性状与其适合度的关系, 探究花性状的表型选择作用。为揭示花性状变化对雌性适合度的影响, 本研究处理展毛翠雀(Delphinium kamaonense var. glabrescens)花萼片大小, 并进行表型选择分析。结果表明: 人为减小展毛翠雀花萼片显著降低了传粉者的访花频率, 但是并没有影响种子产量(种子数和结籽率), 说明展毛翠雀花萼片的大小不影响种子产量, 可能主要吸引传粉昆虫输出花粉。通过雌性适合度(种子数量)估计表型选择梯度, 发现花萼片大小(长和宽)没有受到显著的直接选择梯度。但是, 花距长受到显著的线性选差和选择梯度, 表明花距的延长能够增加种子产量。本研究表明展毛翠雀花性状受到选择的作用, 但萼片和花距有不同的功能, 分别影响传粉者访问频率和种子产量。

Phenotypic selection analysis of flower traits in Delphinium kamaonense var. glabrescens (Ranunculaceae)

It has been widely accepted that pollinator-mediated selection is responsible for the evolution of flower traits. To date, two distinct methods of phenotypic manipulation and phenotypic selection analyses have been used to demonstrate flower function and potential selection. However, empirical studies combining both methods are rare in wild plants. Through manipulating sepal size of Delphinium kamaonense var. glabrescens (Ranunculaceae) and performing phenotypic selection analysis, this study examined functions of two flower traits and the potential selection on them. Sepals manipulated to be smaller significantly decreased visitation rate of pollinators, but did not affect seed number per flower or seed set. Sepal size mainly affected pollen export mediated by pollinator attraction rather seed production. Phenotypic selection estimated through female fitness showed no significant gradient with varying sepal width and length. However, significant linear selection differential and selection gradient on the spur length were observed, showing higher seed production in individuals with longer floral spurs. This study suggests different function and potential fitness consequences of floral traits that were subject to natural selection.