Mitochondrial genome rearrangement in a hydrothermal vent-endemic lineage of provannid gastropods provides a new DNA marker for phylogeographical studies

The nucleotide sequences of mitochondrial DNA fragments containing genes for cytochrome c oxidase subunits I and II, ATPase subunits 6 and 8, large and small subunits of rRNA, and 9 tRNAs were determined using 2 genetically distinct representative specimens of the hydrothermal vent-endemic genus, Alviniconcha, and for the hydrothermal vent-endemic species, Ifremeria nautilei (Provannidae: Caenogastropoda: Mollusca). All 3 specimens showed tRNATrp gene translocation. To determine the time point at which this translocation occurred, we determined the nucleotide sequences of fragments containing 7 tRNA genes for another 3 Alviniconcha and 2 Ifremeria specimens, as well as for 7 related species. Our findings indicated that the translocation occurred in a common ancestor of the Alviniconcha and Ifremeria genera. Relatively long non-coding regions were observed on both sides of the tRNATrp gene and at the original position of this gene in all the Alviniconcha and Ifremeria gastropod specimens. Overall, the mitochondrial non-coding regions appear to provide much more information about genetic structure than the mitochondrial COI gene does and could therefore be a valuable marker for future studies.