Rapid and collective determination of the complete “hot-spring frog” mitochondrial genome containing long repeat regions using Nanopore sequencing

The mitochondrial genome (mt-genome) is one of the promising molecular markers for phylogenetics and population genetics. Recently, various mt-genomes have been determined rapidly by using massively parallel sequencers. However, the control region (CR, also called D-loop) in mt-genomes remain difficult to precisely determine due to the presence of repeat regions. Here, using Nanopore sequencing, we succeeded in rapid and collective determination of complete mt-genome of the hot-spring frog, Buergeria japonica , and found that its mt-genome size was 22,274 bp including CR (6,929 bp) with two types of tandem repeat motifs forming repeat regions. Comparison of assemble strategies revealed that the long- and short-read data combined together enabled efficient determination of the CR, but the short-read data alone did not. The B. japonica CR was longer than that of a congenic species inhabiting cooler climate areas, Buergeria buergeri , because of the long repeat regions in the former. During the thermal adaptation of B. japonica , the longer repeat regions in its CR may have accumulated within a short period after divergence from B. buergeri . ### Competing Interest Statement The authors have declared no competing interest.