The Ecology Maintaining Mechanism In A Gynodioecious Sexual System Plant Cyananthus Delavayi

Cyananthus delavayi(Campanulaceae)belong to gynodioecious sexual system species.There have a stable survival phenomenon between female and hermaphrodite.In theory,female must keep advantage of seeds between quantity and quality in gynodioecious.Our field study site is located in the Shangri-la Alpine Botanical Garden(Shangri-la County,northwest of Yunnan province).We studied many aspects in the population of Cyananthus delavayi,including floral traits,sex ratio,ovules number,floral longevity,floral display,visit frequency and pollination efficiency,etc.We try to explain the doubted that how to get higher female fitness advantage in Cyananthus delavayi preliminary,and provide more convincing evidence for the ecology maintaining mechanism of gynodioecious sexual system,and Enrich our understanding about gynodioecious.The results show as follows:1.In floral traits aspect,petal length,petals width,corolla tube length and corolla diameter hermaphrodite flowers were greater than female flowers(P<0.05).2.There were significant differences in the visit frequency of bumble bee,halictid bee and hoverfly between female and hermaphrodite,hoverfly and halictid pollinators have a higher visited frequency to hermaphrodite(P<0.05),however,bumble bee are contrary.At the same time,On the one hand,through the analysis of pollens number deposited on the stigma and seeds number of single-visited,bumble bee and hoverfly carried more pollen to the hermaphrodite(P<0.05),On the contrary,halicitd do not have differences;on the other hand,the seeds number were higher in female by halictid and bumble bee visited.So we concluded that:bumble bee and halictid were main pollinators of Cyananthus delavayi.3.Through the analysis of correlation relationship between single-visited pollens number deposited on the stigma and seeds number,we concluded that the seed number as the indicator is more reliable to measure pollination efficiency.4.The ovule numbers no difference between female and hermaphrodite(P =0.146),by control the number of pollens removed in the hermaphrodite flower,along with the female phase maintain time prolonged,the seeds number also increased(P>0.05).The result indicated that the longer female phase maintain time maybe is an important factors to affect female fitness advantage.5.In the natural,relative to hermaphrodite,female individual have a bigger floral display.Therefore,under the condition of manual control the floral display size,single flower will produce more seeds along with the floral increased.The result indicated that a relatively large floral display will produce positive role to female fitness advantage.In conclusion,for the female individual in gynodioecious sexual system,the following three aspects is very important for female fitness advantage:the longer female phase maintain time,a relatively large floral display,more effectively pollinators visited.