Lophotrochozoan mitochondrial genomes.

Progress in both molecular techniques and phylogenetic methods has challenged many of the interpretations of traditional taxonomy. One example is in the recognition of the animal superphylum Lophotrochozoa (annelids, mollusks, echiurans, platyhelminthes, brachiopods, and other phyla), although the relationships within this group and the inclusion of some phyla remain uncertain. While much of this progress in phylogenetic reconstruction has been based on comparing single gene sequences, there are also higher order features of genomes, such as the relative order of genes, that have contributed, and this seems likely to be even more fruitful in the future. Even though tremendous progress is being made on the sequence determination of whole nuclear genomes, the dataset of choice for genome-level characters for many animals across a broad taxonomic range remains mitochondrial genomes. We review here what is known about mitochondrial genomes of the lophotrochozoans and how comparisons of some of these features may be useful in discerning the phylogeny of this group.