以风媒传粉类群禾本科为例探究花粉粒大小的演化

风媒传粉植物花粉粒大小在种间存在差异，但风媒传粉的物种经历相同的选择压力——风力，那么其花粉大小差异是如何形成的呢？为探索这一科学问题，本项目计划以云南香格里拉高山草甸中广泛分布的风媒传粉类群禾本科植物为实验系统，验证花粉粒大小演化的零假说（生殖结构同步增长假说）和传粉后假说（花粉粒大小受到在柱头上萌发及受精成功的选择）。通过研究禾本科植物的花序及花部特征，进行系统发育独立对比分析以及设计室内花粉散布模拟实验等内容，以期：明确花粉大小是否与花大小、花柱长度及柱头深度呈正相关，解析风媒传粉植物花粉大小与花粉散布距离及柱头捕获的关系，揭示风媒植物花粉粒大小演化的动力因素。本研究结果不仅为阐释风媒植物花粉的进化提供了实验证据，还可为全面揭示植物雄性生殖策略和花部特征的演化提供重要理论依据。

Pollen grain size of wind-pollinated plants varies greatly among species, although all these species rely on wind to pollinate, so, what is the evolutionary driving force of interspecific variation in pollen grain size? To explore this question, wind-pollinated grasses (Poaceae) are studied as a model system to test the null hypothesis (allometry growth of reproductive structures) and the post-pollination hypothesis (pollen germination on stigma and fertilization success). With the studies of inflorescence and floral traits, phylogenetically independent contrast analyses and artificial pollen dispersal experiments, we aim to test the positive correlation between pollen grain size and flower size, style length and stigma depth, and to test the associations between pollen size and pollen dispersal distance/ capture capacity of stigma on pollen. Our results will not only provide empirical evidences for the adaptative significances of pollen size in wind-pollinated species, but also enhance our understanding on the reproductive strategy of male function and on the evolution of flower traits.