Mitochondrial genomes of Clymenella torquata (Maldanidae) and Riftia pachyptila (Siboglinidae) : evidence for conserved gene order in Annelida

Author Posting. © The Authors, 2004. This is the author's version of the work. It is posted here by permission of Society for Molecular Biology and Evolution for personal use, not for redistribution. The definitive version was published in Molecular Biology and Evolution 22 (2005): 210-222, doi:10.1093/molbev/msi008.Mitochondrial genomes are useful tools for inferring evolutionary history. However, many taxa are poorly represented by available data. Thus, to further understand the phylogenetic potential of complete mitochondrial genome sequence data in Annelida (segmented worms), we examined the complete mitochondrial sequence for Clymenella torquata (Maldanidae) and an estimated 80% of the sequence of Riftia pachyptila (Siboglinidae). These genomes have remarkably similar gene orders to previously published annelid genomes, suggesting that gene order is conserved across annelids. This result is interesting given the high variation seen in the closely related Mollusca and Brachiopoda. Phylogenetic analyses of DNA sequence, amino acid sequence and gene order all support the recent hypothesis that Sipuncula and Annelida are closely related. Our findings suggest that gene order data is of limited utility in annelids but that sequence data holds promise. Additionally, these genomes show AT bias (~66%) and codon usage biases, but have a typical gene complement for bilaterian mitochondrial genomes.Support by CICOR to RJM is gratefully acknowledged. This work was support by the National Science Foundation grants (DEB-0075618 and EAR-0120646) to KMH