Phylogenetic Conservatism Of The Pollination Network In An Alpine Meadow Of Hongyuan,Northeastern Sichuan Province,China

The evolutionary change of the species group on one side servers as a selective force on the species group of the other side of ecological networks including both mutualistic and antagonistic ones.Such a coevolution may strengthen or weaken the phylogenetic association between the species groups,i.e.closely related species are not necessarily associated with closely related partner species in the networks.Similarly,closely related species on one side do not necessarily interact with compositionally similar partner species,and vice versa for the other side in the network.Studying phylogenetic conservatism is helpful to understanding the ecological mechanism underlying the coadaptation and coevolution between interacting species.Studies have suggested that closely related pollinators tend to interact more with closely related plants and are more likely interact with compositionally similar plants,but closely related plants do not necessarily interact more with compositionally similar pollinators.However,empirical evidence is still largely lacking particularly for the pollinator networks with a high species richness of both plants and pollinators.This study aims to identify pollinator insects and determine the phylogenetic conservatism of a pollination network based on previous field surveys on pollinator insects and the pollination network in an alpine meadow on eastern Tibetan Plateau.The insect identification was conducted using combined morphology and COI barcoding technology.The phylogenetic conservatism was determined by ParaFit test to address whether closely related insects visited closely related plants and by Mantel test to address whether closely related insect visited compositionally similar plants and vice versa.Identified pollinator insects belonged to 189 species of 126 genera and 57 families and 5 orders including Hymenoptera,Lepidoptera,Diptera,Coleoptera and Hemiptera.The pollinator species richness was higher compared with many other types of grasslands.In the pollination network including 53 plant species and 76 pollinator species,closely related insects were found to more frequently visit closely related plants.This indicates that species phylogeny affects network structure.Moreover,closely related insect visited compositionally similar plants but closely related plants were not pollinated by compositionally similar insects,indicating an asymmetry of phylogenetic conservatism.This asymmetry might result from the strong plant-plant competition for pollinators.In summary,there is a high species richness of pollinator insects in the alpine meadow and the pollination network is of asymmetric phylogenetic conservatism.It can be suggested that the plant-plant competition is the original selection force for the plant-pollinator coevolution despite a significant phylogenic association between the plants and insects.