The lepidopteran mitochondrial control region: structure and evolution

For several species of lepidoptera, most of the approximately 350-bpmitochondrial control-region sequences were determined. Six of thesespecies are in one genus, Jalmenus; are closely related; and are believedto have undergone recent rapid speciation. Recent speciation was supportedby the observation of low interspecific sequence divergence. Thus, nouseful phylogeny could be constructed for the genus. Despite a surprisingconservation of control-region length, there was little conservation ofprimary sequences either among the three lepidopteran genera or betweenlepidoptera and Drosophila. Analysis of secondary structure indicated onlyone possible feature in common--inferred stem loops with higher-than-randomfolding energies-- although the positions of the structures in differentspecies were unrelated to regions of primary sequence similarity. Wesuggest that the conserved, short length of control regions is related tothe observed lack of heteroplasmy in lepidopteran mitochondrial genomes. Inaddition, determination of flanking sequences for one Jalmenus speciesindicated (i) only weak support for the available model of insect 12S rRNAstructure and (ii) that tRNA translocation is a frequent event in theevolution of insect mitochondrial genomes.