title: Evolution of mitochondrial gene order in Annelida.
abstract: Annelida is a highly diverse animal group with over 21,000 described species. As part of Lophotrochozoa, the vast majority of annelids are currently classified into two groups: Errantia and Sedentaria, together forming Pleistoannelida. Besides these taxa, Sipuncula, Amphinomidae, Chaetopteridae, Oweniidae and Magelonidae can be found branching at the base of the tree. Comparisons of mitochondrial genomes have been used to investigate phylogenetic relationship within animal taxa. Complete annelid mitochondrial genomes are available for some Sedentaria and Errantia and in most cases exhibit a highly conserved gene order. Only two complete genomes have been published from the basal branching lineages and these are restricted to Sipuncula. We describe the first complete mitochondrial genome sequences for all other basal branching annelid families: Owenia fusiformis (Oweniidae), Magelona mirabilis (Magelonidae), Eurythoe complanata (Amphinomidae), Chaetopterus variopedatus and Phyllochaetopterus sp. (Chaetopteridae). The mitochondrial gene order of all these taxa is substantially different from the pattern found in Pleistoannelida. Additionally, we report the first mitochondrial genomes in Annelida that encode genes on both strands. Our findings demonstrate that the supposedly highly conserved mitochondrial gene order suggested for Annelida is restricted to Pleistoannelida, representing the ground pattern of this group. All investigated basal branching annelid taxa show a completely different arrangement of genes than observed in Pleistoannelida. The gene order of protein coding and ribosomal genes in Magelona mirabilis differs only in two transposition events from a putative lophotrochozoan ground pattern and might be the closest to an ancestral annelid pattern. The mitochondrial genomes of Myzostomida show the conserved pattern of Pleistoannelida, thereby supporting their inclusion in this taxon.
authors: Molecular Evolution and Animal Systematics, University of Leipzig, Talstr. 33, 04103 Leipzig, Germany; Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany. Electronic address: anne.weigert@uni-leipzig.de.
authors: Anne
authors: A
authors: Weigert
authors: Zoological Research Museum Alexander Koenig, Adenauerallee 160, 53113 Bonn, Germany. Electronic address: A.Golombek@gmx.de.
authors: Anja
authors: A
authors: Golombek
authors: Molecular Evolution and Animal Systematics, University of Leipzig, Talstr. 33, 04103 Leipzig, Germany. Electronic address: michael.gerth@uni-leipzig.de.
authors: Michael
authors: M
authors: Gerth
authors: Molecular Evolution and Animal Systematics, University of Leipzig, Talstr. 33, 04103 Leipzig, Germany. Electronic address: francine.schwarz@yahoo.de.
authors: Francine
authors: F
authors: Schwarz
authors: Zoological Research Museum Alexander Koenig, Adenauerallee 160, 53113 Bonn, Germany. Electronic address: torsten.struck.zfmk@uni-bonn.de.
authors: Torsten H
authors: TH
authors: Struck
authors: Molecular Evolution and Animal Systematics, University of Leipzig, Talstr. 33, 04103 Leipzig, Germany; German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103 Leipzig, Germany. Electronic address: bleidorn@uni-leipzig.de.
authors: Christoph
authors: C
authors: Bleidorn
mesh_terms: D000818:Animals; D000845:Annelida / Q000145:classification* / Q000235:genetics*; D019143:Evolution, Molecular; D023061:Gene Order; D050259:Genes, Mitochondrial / Q000235:genetics*; D020459:Genes, rRNA / Q000235:genetics; D054629:Genome, Mitochondrial / Q000235:genetics; D010802:Phylogeny; D011077:Polychaeta / Q000145:classification / Q000235:genetics
keywords: Annelida; Gene order; Mitochondrial genomes; Next Generation Sequencing