Mitogenomics reveals phylogeny and repeated motifs in control regions of the deep-sea family Siboglinidae (Annelida)

• Published in: Molecular phylogenetics and evolution 2015-04, Vol.85, p.221-229
• Main Authors: Li, Yuanning, Kocot, Kevin M., Schander, Christoffer, Santos, Scott R., Thornhill, Daniel J., Halanych, Kenneth M.
• Format: Article
• Language: English
• Subjects: Animals; Biological Evolution; Control region; DNA, Mitochondrial - genetics; Ecosystem; Genome, Mitochondrial; Mitogenomic; Osedax; Phylogeny; Polychaeta - classification; Polychaeta - genetics; Sequence Analysis, DNA; Size variations; Symbiosis; Transcriptome
• ISSN: 1055-7903; 1095-9513
• DOI: 10.1016/j.ympev.2015.02.008

[Display omitted] •Phylogenetic analyses suggest Osedax is most closely related to the Vestimentifera+Sclerolinum clade, rather than Frenulata.•Results imply Osedax may have evolved from a lineage utilizing chemoautotrophic symbionts.•Significant size variation and repeated nucleotide motifs were found in control regions of these mt genomes.•10 complete and 2 partial mitochondrial genomes and one transcriptome were newly sequenced. Deep-sea tubeworms in the annelid family Siboglinidae have drawn considerable interest regarding their ecology and evolutionary biology. As adults, they lack a digestive tract and rely on endosymbionts for nutrition. Moreover, they are important members of chemosynthetic environments including hydrothermal vents, cold seeps, muddy sediments, and whale bones. Evolution and diversification of siboglinids has been associated with host-symbiont relationships and reducing habitats. Despite their importance, the taxonomy and phylogenetics of this clade are debated due to conflicting results. In this study, 10 complete and 2 partial mitochondrial genomes and one transcriptome were sequenced and analyzed to address siboglinid evolution. Notably, repeated nucleotide motifs were found in control regions of these mt genomes, which may explain previous challenges of sequencing siboglinid mt genomes. Phylogenetic analyses of amino acid and nucleotide datasets were conducted in order to infer evolutionary history. Both analyses generally had strong nodal support and suggest Osedax is most closely related to the Vestimentifera+Sclerolinum clade, rather than Frenulata, as recently reported. These results imply Osedax, the only siboglinid lineage with heterotrophic endosymbionts, evolved from a lineage utilizing chemoautotrophic symbionts.