Studies On The Comparative Mitochondrial Genomics And Phylogeny Of Dorcus S.l.(Coleoptera:Lucanidae)

The systematics of Dorcus s.l.has long been one of the most serious problems in Lucanidae.Many generic taxa are involved in this braod sense genus due to their complex,variable and transitional external characters,which caused a greal deal of taxonomic changes.lt is necessary to carried out the molecular phylogeny for exploring the generic and species relationship within this problematic genus.However,there are less work was focus on this issue.The mitochondrial genome has a faster evolution rate,more stable gene arrangement and composition and more abundant and deeper genetic information than gene fragments.lt has been widely used in the phylogenetic research of various groups of insects.So we sequenced the mitochondrial genomes of representative species of the Dorcus s.l.-through high-throughput sequencing,comparing their mitochondrial genome characteristics and reconstruct phylogenetic trees.The main contributions of this work are as follows:(1)A total of 24 mitochondrial genome sequences were obtained from 4 genera of Dorcus s.l.These sequences ranged in length from 15.785-20,052 bp and the order was conservative,no gene rearrangement occurred,which was consistent with the mitochondrial genome structure of classical insects.The mitochondrial genome of each species has a high AT content,and the AT-skew and GC-skew of the control region have large differences.ATT.TTA.TTT.and ATA are the four most commonly used codons in protein-coding genes.Among the protein-coding genes,the ND4 gene has the fastest evolution rate and the COI gene has the slowest evolution rate.(2)The large intergenic spacer was found only in 7 species,and the large gene interval of 5 species appeared in the form of a discontinuous repeat(TACTAAATT)between the trnAser(UCN)-ND1 gene;the other 2 large intergenic spacer is between ND2-trnAtyr or trnaAAla-trnAArg,there is no repeat sequence.The phylogenetic analysis also shows whether the large intergenic spacer has a mosaic structure.It is speculated that this feature is more in the evolution of the mitochondrial genome of the Lucanidae.(3)Phylogenetic analysis supports the Dorcus s.l.is monophyletic within the family Lucanidae.Among them,the monophyly of Serrognathus,Hemisodorcus,and Falcicornis were supported.But the Dorcus s.str.is a polyphyly:the species of Dorcus macleayii,Dorcus donckieri and Hemisodorcus are clustered together;Dorcus tanakai.Dorcus linwenhsini,Dorcus hirticornis,Dorcus cervulus,Dorcus striatipennis davidi are clustered into a clade:D.tenuihirsutus.D.ursulus and D.velutinus also clustered into another clade.In the present study,we study used mitochondrial genomic data to investigate the phylogenetic problems of the Dorcus s.l.first time.Providing a reference for the phylogenetics of the Dorcus s.l.and accumulating mitochondrial genomic data for the Lucanidae.