Phylogenetic signal in mitochondrial gene order of platygastroid wasps

The insect mitochondrial genome generally consists of 13 protein-coding genes, 22 transfer RNA genes, and two ribosomal RNA genes. Among most groups, the order of these genes in the genome and the coding strand is invariant. Among the parasitoid wasps of the superfamily Platygastroidea the position of the protein-coding genes is constant, but, in contrast, the location of the tRNA genes varies significantly. Earlier workers have suggested that changes in gene order are relatively rare events, in contrast to the overall rapid evolution of DNA sequences in the mitochondrion. This supposed rarity, then, may provide a robust phylogenetic signal to infer relationships. The extreme variability in tRNA gene position in Platygastroidea has made it difficult to tease out this signal. We revisit these data on gene order among 25 genera in the superfamily, including 22 new mitochondrial genomic sequences. We analyze and interpret the data in the context of recently proposed hypotheses of relationships within the superfamily.