Mitochondrial Genomes of Six Snakes (Lycodon) and Implications for Their Phylogeny

The mitogenomes of these six species ranged from 17,143 to 17,298 bp in length and con-sisted of 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), 2 ribosomal RNA genes (rRNAs), and 2 control regions. The nucleotide composition of the Colu-bridae mitogenomes was comparable with an A + T composition ranging from 52.1% to 58.8% except for the trnS1 and trnC. All the tRNAs could fold into a stable secondary structure. The Pi and Ka/Ks values suggested that atp8 was the fastest-evolving gene, while cox1 was the most conserved gene. Bayesian inference and maximum likelihood phylogenetic analyses yielded consistent results, with the six sequenced species clus-tering together with their congeneric species. These findings will provide valuable references for further research on the phylogeny of Colubridae.