How Do Co-flowering Plants Shared Pollination Avoid Heterospecific Pollen Deposition ?

When multiple plants are simultaneously flowering in natural communities,flower visitors usually forage rewards not only from one plant species.Pollinator interspecific movement may transfer heterospecific pollen to stigmas.How do co-flowering plants avoid heterospecific pollen deposition?What factors mainly contribute to pollinator interspecific foraging behaviors?To address these questions,we studied pollinator foraging behaviors and heterospecific pollen receipt,pollen placement on insect bodies and floral morphologies for two years in an alpine meadow at the Shangri-La Alpine Botanical Garden,Yunnan Province,China.To develop a network and its structure between plants and pollinators in the alpine meadow,the interactions between 18 co-flowering plant species and pollinators were investigated.Opening flowers per day were counted in the experimental plot to estimate floral abundance of coexisting species.Conspecific and heterospecific pollen deposited on stigmas were counted to estimate heterospecific pollen receipt.The pollinator behavior between plants establishes a connection between plants and plants.It is easy to drop pollen on the next plant stigma during pollination.We conducted a visit to the fixed sample and observed the number and type of pollen on the stigma.The results showed that the proportion of heterospecific pollen on stigmas of the plant was 0%to 15%,which indicated that although pollinators frequently visited each other between different plants,frequent mixed visits did not bring more heterospecific pollen.In the community.The five species of Pedicularis densispica,Astragalus polycladusvar,Trifolium repens,Potentilla lancinata,Euphrasia regelii are at the core of the pollination network.After guess speculation,recording video repeatedly observation,statistics pollinator body part of the pollen species and other series of experiments,the results show that the pollinator in the mixed visit between different plants,the body parts and stigma contact parts,and plant pollen deposit on the body of the pollinator are matched within the species and are different between species.In our two-year study,we further explored the factors that play a key role in the network of visits by measuring community richness and coexistence experiments.The results showed that the community richness was positively correlated with the mixed network(P=0.001).In the environment with high community richness,pollinators are more likely to have mixed visit behaviors.At the same time,the mixed network is positively correlated with the number of coexistence(P=0.001).The more coexistence,the more frequent pollinators mixed visit behavior.However,there was no significant correlation between the pollination network and the hetero specific pollen.Although the pollinators frequently exchanged between several species,the increase in visits did not bring more heterospecific pollen.