Characterization of the complete mitochondrial genome of Cryptotermes domesticus (Blattodea: Kalotermitidae): Genome description and phylogenetic implications

Abstract

The complete mitochondrial genome of Cryptotermes domesticus (Haviland) was sequenced and annotated to study its characteristics and the phylogenetic relationship of C. domesticus to other termite species. The mitogenome of C. domesticus is a circular, close, and double-stranded molecule with a length of 15,655 bp. The sequenced mitogenome contains 37 typical genes, which are highly conserved in gene size, organization, and codon usage. Transfer RNA genes (tRNAs) also have typical secondary structures. All of the 13 protein-coding genes (PCGs) start with an ATN codon, except for nad4, which starts with GTG and terminates with the terminal codon TAA and TAG or the incomplete form T-- (cox2 and nad5). Most tRNAs have a typical cloverleaf structure, except for trnS1, in which this form is replaced by a simple loop and lacks the dihydrouridine (DHU) arm. The nucleotide diversity (Pi) and nonsynonymous (Ka)/synonymous (Ks) mutation rate ratios indicate that nad1, cox1, and cox3 are the most conserved genes, and that cox1 has the lowest rate of evolution. In addition, an 89 bp repeated sequence was found in the A + T-rich region. Phylogenetic analysis was performed using Bayesian inference (BI) and maximum likelihood (ML) methods based on 13 PCGs, and the monophyly of Kalotermitidae was supported.

Keywords: Cryptotermes; Kalotermitidae; mitochondrial genome; phylogenetic analysis.

Figure 1

Circular map of the complete mitogenome of Cryptotermes domesticus. Different colors indicate different types of genes and regions. Genes in the outer circle are located on the J‐strand, and genes in the inner circle are located on the N‐strand.

Figure 2

(a) Relative synonymous codon usage (RSCU) of six species of Kalotermitidae; (b) amino acid composition of six species of Kalotermitidae (the ordinate unit is percentage).

Figure 3

Nucleotide diversity (Pi) and nonsynonymous (Ka)/synonymous (Ks) mutation rate ratios of 13 protein‐coding genes (PCGs) of Kalotermitidae species (the Pi and Ka/Ks values of each PCG are shown under the gene name).

Figure 4

The secondary structures of the transfer RNA genes (tRNAs) in Cryptotermes domesticus mitogenome.

Figure 5

BI and ML analyses of the 13 protein‐coding genes (PCGs) produced similar tree topologies. The ML tree has the same topology as the BI tree, and their support values are reported above and below the nodes, respectively. The phylogram was constructed using the maximum likelihood method by 10,000 bootstrap pseudoreplicates with a standard bootstrap of 1000 replicates. BI, Bayesian inference; ML, maximum likelihood.