Comparative mitogenomic analyses unveil conserved and variable mitogenomic features and phylogeny of Chedrinae fish

Chedrinae  fish,  which  belong  to  Danionidae,  have  important
ornamental,  economic,  and  scientific  value.  At  present,
however,  their  mitogenomic  features  are  unclear  and  their
phylogenetic relationships remain controversial. In this study,
we  presented  five  new  Chedrinae  mitochondrial  genomes
(mitogenomes)  and  analyzed  the  conserved  and  variable
mitogenomic  characteristics  of  17  Chedrinae  fish.  The  gene
composition  and  arrangement  and  secondary  structure  of
transfer  RNAs  (tRNAs)  were  highly  conserved  among  the
Chedrinae  mitogenomes.  However,  the  length  of  the  control
region and base composition were variable. Interestingly, the
mitogenome  of Barilius barila was  unusual,  with  lower  A+T
content  in  the  first  codon  of  protein-coding  genes  (PCGs)
(47.32%  versus  average  of  54.47%)  and  distinct  pattern  of
codons per thousand codons (CDspT). Three Chedrinae fish
had  a  long  tandem  repeat  (>291  bp)  in  the  5'-end  of  the
control  region,  which  may  increase  their  adaptability.  In
addition, tRNALys had notably larger DHU and TΨC loops than
other  tRNAs.  The  phylogenetic  trees  of  the  Chedrinae  fish
suggested  that  the Barilius genus  was  not  a  monophyletic
group  but  could  be  divided  into  two  main  groups  based  on
significant  differences  in  A+T  content.  This  study  provides
insights  into  the  mitogenomic  features  and  phylogenetic
implications  of  Chedrinae  fish,  which  should  benefit  their
systematics and conservation.