Phylogeny Of The Subfamily Eristalinae Based On The DNA Barcoding

Eristalinae belongs to the family Syrphidae,which is the most abundant subfamily of the family Syrphidae and has important biological and economic significance.In the early stage,the identification of the subfamily Eristalinae mainly relied on traditional morphological classification methods.With the development of science and technology,more and more scholars began to use molecular data carry out research,mainly focused on single gene fragments and mitochondrial genomes.However,the former research method contains less genetic information,and the research results are often different based on different species selection or different gene fragments.Although the latter contains more genetic information in a single individual,it often involves a small number of species and lacks sufficient data and representativeness.The results do not fully represent the phylogenetic relationship between families,genera and species.A total of 121 individuals belonging to 118 species,38 genera and 9 tribes of Eristalinae were collected in this study.Among them,26 species belonging to 13 genera and 5 tribes were collected from the field,92 species belonging to 35 genera and 9 tribes were downloaded from Gen Bank,and 3 species belonging to 2 genera of Syrphinae were used as outgroup.Genomic DNA was extracted from the collected specimens by Easy Pure Genomic DNA Kit.The COI,18 S rRNA,28 S rRNA and Cytb gene sequences were amplified by PCR,and the sequencing results of the company were compared and analyzed to identify its accuracy.MEGA-X software was used to analyze the base bias,codon usage frequency,interspecific genetic distance and intergeneric genetic distance of the four genes.Then,MEGA-X and Phylosuite software were used to construct phylogenetic trees by ML,BI and MP methods.The experimental results are as follows:1.The base composition of COI,18 S rRNA,28 S rRNA and Cytb gene fragments all had A + T base bias,and the proportion of variation sites of COI gene and Cytb gene was higher than that of 18 S rRNA gene and 28 S rRNA gene,indicating that the Eristalinae insects were more conservative in the evolution of 18 S rRNA gene and 28 S rRNA gene.2.This study proves that the shorter the gene sequence,the lower the support of the phylogenetic tree results.At the same time,the results of multi-gene joint tree construction are more accurate and more supportive than single-gene tree construction.3.In the phylogenetic study,Callicerini,Cerioidini and Sericomyiini showed monophyly.4.Eristalini is a monophyletic group,and Lejops was the first to be differentiated,which is located at the base of the phylogenetic tree of Eristalini.Helophilus,Phytomia and Mesembrius are monophyletic groups.5.Brachyopini is a polyphyletic group,in which Chrysogaster,Lejogaster and Orthonevra are stable in the phylogenetic tree,and they are sister groups with Chrysosyrphus.Brachyopa and Hammerschmidtia are stable in the phylogenetic tree,and they are sister groups.6.Milesiini is a polyphyletic group,in which Brachypalpoides,Lejota and Xylota are stably clustered into one branch in the phylogenetic tree.Spilomyia and Syritta are stably clustered into one branch and are sister groups to each other.7.The genera Cheilosia,Rhingia,Ferdinandea,Pelecocera and Portevinia in Rhingiini are monophyletic groups.Cheilosia and Rhingia are sister groups,Ferdinandea,Pelecocera and Portevinia are clustered together..8.Merodontini is a monophyletic group,in which Eumerus and Merodon are clustered into one branch and sister groups to each other.9.The tribe Volucellini is monophyletic,and Copestylum is monophyletic.The genera Graptomyza and Volucella are polyphyletic.