Studies On The Comparative Mitochondrial Genomics And Phylogeny Of Insecta

Insect mitochondrial genome has been generally applied in the study of phylogenetic relationships,population structure and phylogeography due to its stable gene content,uniparental inheritance,lack of extensive recombination and high evolve rate.Until now,there has been comparatively limited mt phylogenomics studies on interordinal relationships within the Polyneoptera and Holometabola.Thus,sequencing and analyzing of polyneopteran and holometabolan mitochondrial genomes are important to get better understanding of the evolution of mitochondrial genomes and complex phylogenetic relationships in these two key groups of Insecta.In this study,we conducted a large scale sequencing of polyneopteran and holometabolan mitochondrial genomes,and determined the mitochondrial genomes of 17 insects in the Polyneoptera and 5 insects in the Holometabola.Mitochondrial genomes of many key groups were enriched,such as Embioptera,Trichoptera,Dermaptera.Based on these datasets,the structural traits and evolution of polyneopteran and holometabolan mitochondrial genomes were analyzed,by using comparative genomic and bioinformatics methods.Additionally,we reconstructed the phylogeny of Polyneoptera and Holometabola using complete mitochondrial genome sequences.Conclusions were drawn as following:(1)A high degree of compositional heterogeneity was observed among polyneopteran and holometabolan mitochondrial genomes in both nucleotide and amino acid level.(2)Our findings demonstrate the lineage-specific substitution rate and contrasting rate of mitochondrial genome evolution both across and within polyneopteran and holometabolan orders.(3)The inclusion of rRNA genes and removal of fast evolving sites with the observed variability sorting(OV)method for identifying sites deviating from the mean rates improved the phylogenetic inferences under a site-heterogeneous model.(4)We obtained the tree topology of deep relationships of Holometabola:(Hymenoptera+((Coleopterida+Neuropterida)+(Amphiesmenoptera+Antliophora)))and the tree topology of deep relationships of Polyneoptera:(Dermaptera+(Plecoptera+(Orthoptera+((Grylloblattodea+(Mantophasmatodea+((Zoraptera+Embioptera)+Phasmatodea)))+(Mantodea+Blattodea))))),with the assesse of through data deletion strategies(e.g.,OV-sorting method),and the using site-heterogeneous mixture models.