Mitogenomics reveals phylogenetic relationships of Patellogastropoda (Mollusca, Gastropoda) and dynamic gene rearrangements

Abstract

AbstractPatellogastropoda has been recognized as the most ‘primitive’ group of living Gastropoda and plays important role in littoral marine ecosystems. Both morphological and molecular works have attempted to resolve the phylogenetic framework of Patellogastropoda, but evolutionary relationships among major lineages remain controversial. In addition, a few mitogenomes sequenced of Patellogastropoda exhibit extensive rearrangements; however, it was unclear that which one can represent the ancestral gene arrangement. In this regard, we sequenced 10 new mitochondrial genomes and analysed them with previously published nine mitogenomes and six transcriptomic data which represent six families of Patellogastropoda. A well‐supported phylogeny was reconstructed based on the amino acid sequences of 13 protein‐coding genes, recovered Lottioidea as non‐monophyletic with two well‐supported lineages. Comprehensive taxon sampling in Lottiidae allows us to recover Lottia digitalis sister to Lottia cassis. Comparing gene order among families, genera and species showed that Nacellidae has a conserved gene arrangement which is similar to that of hypothetical ancestral Gastropoda, whereas Lottiidae exhibits extensive rearrangements even without considering the changes of tRNA genes. A chronogram dating mayor cladogenetic events within the group was also reconstructed. Our results provide new insights into the phylogenetic relationships of Patellogastropoda and detect dramatic gene rearrangements within the group.