Comparative mitogenomics of Hymenoptera reveals evolutionary differences in structure and composition.

The rapidly growing number of mitogenomes in Hymenoptera have mostly been used to explain higher level phylogeny, however, there are inadequate studies that focused on the shared and distinctive patterns of mitogenome evolution. Here, the complete mitogenome of Neodiprion sertifer (Symphyta: Diprionidae) was reported for the first time and it was found to be the most rearranged mitogenome in Symphyta, with five rearrangement events. The mitogenome architectures and features were also investigated in 73 hymenopteran species. The observation of positive GC skews may be related with selective forces acting on mitogenomes with the high number of transversions than transitions. The number of rearrangements exhibited negative correlation with T% and positive with C% content, indicating a tight relation between the number of rearrangements and deamination mutations. The rearrangements also displayed a significant increment from Symphyta to Aculeate and transpositions were found to be the most common type. The rrnS-nd2 was the most rearranged gene cluster, revealing the frequent occurrence of illegitimate recombination via duplications. The nucleotide bias was more important in the codon and anticodon interactions than the expected "exact-match" pattern. The conservation rate of tRNAs seems to be unrelated to that of strand location, amino acid composition, codon family degeneracy.