Male Reproductive Fitness And Opportunity For Selection In Sagittaria Trifolia L.under Different Pollination Environments

Plant reproductive fitness is the core of population evolution.In natural populations,environmental factors affect the reproductive fitness of plant individuals,and cause variations in reproductive fitness within the population,which in turn leads to the occurrence of natural selection.Pollinators play an important role in the environmental factors that affect plant reproduction.Exploring the changes and evolution of plant reproductive fitness in different pollination environments is very important to understand the performance and ecological adaptation of plant populations.In this study,the hermaphroditic plant Sagittaria trifolia was used as the research material,and three pollination environments were set up,including limited pollination,half-saturated pollination,and saturated pollination by controlling the access opportunities of pollinating insects.Three clonal ramets of the same genotype were placed in the three pollination environments.Seven microsatellite loci were used for DNA amplification and analyze the paternal parents of the progeny of S.trifolia in two consecutive years.In order to explore the changes of male reproductive fitness and the opportunity for selection of male-female fitness under different environments.The main findings are as follows:1.Pollinator visits : Through observation and statistics on the visits of pollinators,I found that in the two years,there were significant differences in the number of visits and frequency of pollinator visits in the three treatment areas,which made the pollination intensity of the three treatment areas increase gradually.2.Male fitness of S.trifolia : The software Cervus was used to analyze the paternal parents of the seeds produced in the three treatment areas.I statistically analyzed the number of sired seeds of each individual plant.The results showed that the male fitness of plants in a pollination-restricted environment(limited and half-saturated)was lower than that in a pollination-saturated environment,indicating that the male fitness of plants was affected by the pollination environment.3.Opportunity for selection in male and female fitness of S.trifolia :Homogeneity of variance in male and female fitness under three pollination environments was tested,and results showed that the opportunity for selection in male fitness was higher than that in female fitness of all populations,which was in accordance with Bateman's principle.It indicated that the male reproductive success was affected to a stronger degree by the intensity of pollination.In the limited and half-saturated areas,the opportunity for selection in female fitness within the population were significantly higher than those in the saturated treatments,suggesting that the opportunity for selection in female fitness of the population was increased under limited pollination,and the plant traits would experience stronger selection in such environments.In addition,with the gradual saturation of pollination intensity in year 2015,the opportunity for selection for male fitness showed a trend of decreasing at first and then increasing.However,year 2016 showed a gradual decreasing trend.This difference between years may be caused by the change in relative weights between two stages of pollination and post-pollination in male function.In summary,this study conducted paternal analysis on the plants of S.trifolia,and found that the individual male fitness and the opportunity for selection in male and female fitness of populations are closely related to the specific pollination environment.Different pollination environments changed the reproductive fitness of individuals within the population,affected the opportunity for selection,and thus would potentially lead to differential evolutionary rates of related traits.This study also elaborated on the limiting factors of female fitness of S.trifolia under different pollination environments,and compared the reproductive differences of the male and female functions of plants.Together,the research provides us with new ideas and insights for further understanding of the roles of pollinator-mediated selection,and plant male function,and the evolutionary trajectories of plant populations.