Complete Mitochondrial Genomes And Phylogeny Of Three Hipposideridae Bats

Order Chiroptera is a unique group of mammals whose members have attained selfpowered flight as their main mode of locomotion.Chiroptera is rich in species and closely related to humans,which also has a wide geographic distribution.So far,many controversies about the evolution of Chiroptera still exist,especially on higher order element classification problems.At present,molecular biology is still weak in the study of Chiroptera families and related genera,and there are differences between the results of traditional morphology and molecular evidence.However,lack of sufficient molecular data hampers evolutionary and conservation studies.The taxonomy and phylogenetic studies of the Hipposideridae are mostly based on traditional morphology and echolocation calls.Due to the lack of support and validation of molecular data,the taxonomic relationship between the Hipposideridae and its closely related family Rhinolophidae has been controversial.As an extranuclear genetic system,mitochondrial genome has simple structure,easy isolation,stable genome composition and independent replication ability.With the development of molecular biology and sequencing technology,the acquisition of complete mitochondrial genome sequence is more convenient,so it is widely used in population genetics and phylogeny.In this research,the mitochondrial genome sequencing,annotation and analysis of three Hipposideridae species were completed.The mitochondrial genome sequences of these three species were compared with those of other Chiroptera species to explore the evolution characteristics of mitochondrial genome and interspecific variations,which further enriched the mitochondrial genome database of Chiroptera and provided basic data for the study of comparative genomics.In addition,the phylogenetic relationship of taxa with complete mitochondrial genomes of Chiroptera was reconstructed by concatenated DNA and amino acid sequences of mitochondrial protein-coding genes downloaded from GenBank.1.The mitochondrial genomes of Hipposideros pomona,Hipposideros larvatus and Aselliscus stoliczkanus were sequenced by next-generation sequencing and the mitochondrial genome sequence of each species was annotated by bioinformatics.for the first time.The size of mitochondrial genome,base composition,genome composition and sequence,codon usage and secondary structure of tRNA were analyzed.Mitochondrial genomes of H.pomona,H.larvatus and A.stoliczkanus are identical in structure,which all contain 13 protein-coding genes,22 tRNA genes,2 rRNA genes and a non-coding control region.2.The method of comparative mitogenomic approach were used to analyze the genome structure,intraspecific and interspecific similarities and differences.The sequence and transcriptional direction of protein-coding genes in H.pomona and H.larvatus were consistent with those reported in other species.However,compared with the former two,the A.stoliczkanus contained a redundant copy of tRNA-Gln between 12 S rRNA and tRNA-Val,and the deletion of tRNA-Gly was detected between COIII and ND3.Repetition and deletion did not significantly affect codon preference,which may be related to the time limit of mutation accumulation and the compactness of mtDNA.3.The A + T contents of the three species were all above 55%,and the length of AT enrichment zone was different.The strong A + T bias existed in the base composition of each component of the mitochondrial genome of the three species,indicating that the mitochondrial genome had a strong evolutionary selection pressure of CG ? AT in the evolutionary process.Most of protein-coding genes in the mitochondrial genome of three species use typical ATN as the starting codon and complete TAA or TAG as the terminating codon.However,COIII and ND4 of H.pomona use incomplete TA and T as termination codons,respectively.Among the protein coding genes,codons and amino acids are highly biased,and the four most frequently used amino acids are Leu,Phe,ILe and Ser.4.Comparing the complete mitochondrial genome sequences of the three species by bioinformatics method,it was found that there were slight differences among the three species in the base composition,gene homology,gene overlap region and spacer region of the mitochondrial genome.Based on the mitochondrial genome data of other species in Chiroptera,the genetic distances of mtDNA sequences between different species were calculated.Based on PCGs sequences in the mitochondrial genome,phylogenetic trees were constructed using BI and ML analysis methods.The topological structures of phylogenetic trees were similar.The results supported the classification systems of Yinpterochiroptera and Yangochiroptera.