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性二态是性别分离植物的常见性状,对植物的雌性和雄性功能可能产生不同的影响.本文以青藏高原特有植物银露梅(Dasiphora glabra)为研究对象,利用银露梅同时存在两性、雌性和雄性植株的种群,探讨银露梅与传粉相关的花特征性二态现象及其对传粉者访问、花粉流和结实的影响.另外,本文还利用流式细胞仪检查了两性植株、雄性植株和雌性植株之间基因组大小的差异.研究结果表明:银露梅雌性植株和雄性植株数量约占种群中植株总数量的40％,表明银露梅两性植株数量多于雄性和雌性的植株数量.两性植株的花数量显著多于雄性和雌性植株的花数量.雄花的花大小显著大于雌花和两性花的花大小.雄花的花粉数量与两性花的花粉数量没有差异,但是雌花的胚珠数量显著高于两性花的胚珠数量.双翅目的蝇类是银露梅最主要的访花者,尽管访花者偏好访问更大的花,但是在花间连续访问对大花没有表现出偏好.模拟花粉流实验表明,两性植株和雄性植株的有效花粉转移都很低,从而导致较低的结实率.雌性植株和雄性植株的DNA含量约为两性植株的4倍,并且单性植株和两性植株之间相互授粉不能结实.以上结果表明,与两性花相比,雌花和雄花在与传粉相关的花特征二态性上分别在雌性和雄性功能上表现出优势,但这种优势在很大程度上被低效的花粉转移所掩盖.银露梅的雌性植株和雄性植株经历了多倍化事件,导致与两性植株之间存在繁殖隔离,从而维持了3种性别植株的共存.“,”Aims Sexual dimorphism is a common trait in plants with sex separation,which could influence female and male functions differently.In a subdioecious population of Dasiphora glabra on the Qinghai-Tibet Plateau,we investigated sexual dimorphism of floral traits and their effects on pollinator visitation,pollen flow and seed production.We also examined differences in genome size of hermaphroditic and dioecious plants.Methods We examined sexual dimorphism in flower number,flower size,and pollen and ovule production in a subdioecious population of D.glabra.We compared pollinator visitation,pollen dispersal and seed production between sexes.We also examined the genome size of three sex morphs using flow cytometry.Important Findings The number of hermaphroditic plants was significantly more than that of male and female plants,and dioecious plants accounted for ca.40％in the study population.Hermaphroditic plants produced significantly more flowers than male and female plants.Flower size of male flowers was significantly larger than that of female and hermaphroditic flowers.Male flowers did not produce more pollen grains than hermaphroditic flowers,but female flowers produced more ovules than hermaphroditic flowers.Flies were the most frequent flower visitors and preferred large flowers,but their movements between flowers did not show any preference to large flowers.Simulated pollen flows suggested that effective pollen transfer was generally low for both hermaphroditic and male flowers,corresponding to the low seed set of naturally pollinated flowers.DNA contents of male and female plants were ca.four times than those of hermaphroditic plants.These results suggest male and female individuals have undergone polyploidy events and thus are not compatible with hermaphroditic individuals.Sexual dimorphism in floral traits in relation to pollination of dioecious plants might show an advantage in female and male functions,but this advantage is masked largely by low effectiveness of pollen transfer.