Molecular Phylogeny And Biogeography Of Chloropidae From China(Diptera)

Chloropidae is one of the most diverse families of Carnoidea(Diptera)in the terms of the number of species.It contains 203 genera and more than 3,000 species in the world and distributes in all zoogeographic regions,with diversitified feeding habits.The short evolutionary history made them an ideal model group for the study of insect diversity and evolutionary radiation.Therefore,studying the species diversity pattern and the determined ecological factors of grass flies,resolving the phylogenietic relationship will be helpful for understanding the evolutionary history of Chloropidae and even Diptera,and providing useful evidence for the conservation and utilization of biodiversity of Chloropid flies.In this study,we reconstructed phylogenetic framework of Chloropidae using molecular data(mitochondrial genomes,multi-genes combine)from a comprehensive sampling collected in China,revealed the mitochondrial genome structural characteristics of Chloropidae,and analysed the biogeography of Chloropidae combined with Geographic Information System(GIS)analysis,ecological niche modeling,divergence time estimates and ancestral distribution reconstruction.The main results of this study are listed as below:(1)11 mitochondrial genomes of Chloropidae were sequenced and annotated.Basic structure and features of mitochondrial genomes were also compared.These mitochondrial genomes are consistent with the typical Dipteran mitochondrial genomes,consisting of 37 genes and a variable-length control region.In addition,gene arrangement structure and base composition of Chloropide mitochondrial genome are high conservation.The value of nucleotide diversity and genetic distances of Chloropinae are higher than other three subfamilies.(2)The phylogenetic relationship of Chloropidae was reconstructed by using the perspective of molecular data for the first time.The monophyly of Chloropidae and validity of Rhodesiellinae were proved based on phylogeny analyses of mitochondrial genomes data.The phylogenetic relationship of 81 species in 43 genera of Chloropid flies was reconstructed based on multiple genes data(four mitochondrial gene fragments: COI,CytB,12S rRNA,16S rRNA and two nuclear gene fragments: 28S rRNA,CAD)by increasing the size of samples.The results showed that the Oscinellinae,Chloropinae,Rhodesiellinae,Siphonellopsinae were all monophyletic groups and the phylogenetic relationship of four subfamilies was(Siphonellopsinae+(Oscinellinae +(Chloropinae + Rhodesiellinae))).(3)According to the general data of the geograpgical distribition,the distribution pattern of species diversity and the evolutionary history of Chloropidae in China were revealed for the first time.The results showed that high species richness and areas of endemism were mainly lacated on islands and mountains in China,four endemic areas of Chloropidae,Linzhi of Tibet,Huairou of Beijing and Xiaowutai Mountain,were identified.Temperature and precipitation are the main factors that affect the distribution of Chloropidae and Western of Sichuan,southern of China,Beijing and its surrounding areas are highly suitable distribution areas of grass flies.During LIG to LGM,the suitable areas of Chloropidae expanded obviously.Under the future climatic conditions,the suitable area range of Chloropidae will have a tendency to migrate to the north and southwest.The results of historical biogeographic analysis suggested that Chloropidae might originate in the southwest of China in Eocene about 44.69 Ma,dispersal and long-distance migration were the main factors in shaping the current geographic distribution.In its evolutionary history,Poaceae divergence and dispersal,climate changes during the glacial period may have played an important role in the evolutionary history of Chloropidae.