Mitogenome of the small abalone Haliotis diversicolor Reeve and phylogenetic analysis within Gastropoda

The complete mitochondrial coding regions of three small abalones Haliotis diversicolor Reeve, two collected from Vietnam and one from southern China, were successfully sequenced. The molecular feature of the mitochondrial genome is identical with the general description of the family Haliotidae mtDNAs that have been sequenced so far. The sequenced nucleotides are 16,186-16,266bp in length. The mitogenome encodes 13 protein-coding genes, 2 ribosomal RNA genes, and 22 transfer RNA genes. Between adjacent genes trnH and nad5 there is an overlapping region. Comparison of the ratios of Ka and Ks among four species of Haliotis (H. diversicolor, H. discus hannai, H. rubra and H. tuberculata tuberculata) reveals that values of Ka/Ks in some NADH dehydrogenase and ATPase genes such as nad2, nad6 and atp8 are higher than those in other mitochondrial genes. Genome-wide gene arrangement among four species of Haliotis has been compared. Although all gene arrangement is the same in H. diversicolor, H. discus hannai and H. rubra, the location of trnS₂ and trnF in H. tuberculata tuberculata are inter-exchanged. Both gene arrangement and phylogenetic analysis support that the family Haliotidae is at a relatively primordial phylogenetic position in Gastropoda. Through alignment between Vietnam and southern China individuals, 111 SNPs are detected, most SNPs are synonymous mutations, and 7, 94 and 10 SNPs are observed at NCR, protein-coding region and RNA region, respectively. The result of SNP analysis also demonstrates that the difference is mainly in some NADH dehydrogenase genes between the Vietnam and southern China individuals.