The mitogenome of Gammarus duebeni (Crustacea Amphipoda): A new gene order and non-neutral sequence evolution of tandem repeats in the control region.

We determined the complete mitogenome sequence of Gammarus duebeni (Peracarida, Amphipoda). The mitogenome is circular and has a length of 15,651bp. The content corresponds to typical mitogenomes of metazoans. The gene order and transcriptional polarity of the protein-coding genes is identical to the pancrustacean ground pattern. Six tRNA genes are rearranged, making the gene order unique. Thus it will bring forward the understanding of mitogenome evolution within the Peracarida, for which much more derived gene orders are known. We postulate that the gene string trnA-trnS1 (AGN)-trnN-trnE-trnR constitutes an apomorphic character for the Amphipoda. In contrast to the relatively large genome size, we found two extremely truncated rRNA genes. The rrnL gene is the shortest (986bp) reported up until now for crustaceans. A six-time imperfect tandem repeat was observed within the control region. The inferred deterministic pattern of variation between the repeat units makes it likely, that functional constraints play an important role in the evolutionary dynamics and extant appearance of the repeat array.