title: Relationships within Cladobranchia (Gastropoda: Nudibranchia) based on RNA-Seq data: an initial investigation.
abstract: Cladobranchia (Gastropoda: Nudibranchia) is a diverse (approx. 1000 species) but understudied group of sea slug molluscs. In order to fully comprehend the diversity of nudibranchs and the evolution of character traits within Cladobranchia, a solid understanding of evolutionary relationships is necessary. To date, only two direct attempts have been made to understand the evolutionary relationships within Cladobranchia, neither of which resulted in well-supported phylogenetic hypotheses. In addition to these studies, several others have addressed some of the relationships within this clade while investigating the evolutionary history of more inclusive groups (Nudibranchia and Euthyneura). However, all of the resulting phylogenetic hypotheses contain conflicting topologies within Cladobranchia. In this study, we address some of these long-standing issues regarding the evolutionary history of Cladobranchia using RNA-Seq data (transcriptomes). We sequenced 16 transcriptomes and combined these with four transcriptomes from the NCBI Sequence Read Archive. Transcript assembly using Trinity and orthology determination using HaMStR yielded 839 orthologous groups for analysis. These data provide a well-supported and almost fully resolved phylogenetic hypothesis for Cladobranchia. Our results support the monophyly of Cladobranchia and the sub-clade Aeolidida, but reject the monophyly of Dendronotida.
authors.affiliation: Laboratory of Molecular Evolution, Center for Bioinformatics and Computational Biology , University of Maryland, College Park , MD 20742, USA ; NMFS, National Systematics Laboratory , National Museum of Natural History, Smithsonian Institution , MRC-153, PO Box 37012, Washington, DC 20013, USA.
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Goodheart
authors.affiliation: Laboratory of Molecular Evolution, Center for Bioinformatics and Computational Biology , University of Maryland, College Park , MD 20742, USA.
authors.forename: Adam L
authors.initials: AL
authors.lastname: Bazinet
authors.affiliation: NMFS, National Systematics Laboratory , National Museum of Natural History, Smithsonian Institution , MRC-153, PO Box 37012, Washington, DC 20013, USA.
authors.forename: Allen G
authors.initials: AG
authors.lastname: Collins
authors.affiliation: Laboratory of Molecular Evolution, Center for Bioinformatics and Computational Biology , University of Maryland, College Park , MD 20742, USA.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Cummings
keywords: Mollusca; RNA-Seq; nudibranchs; phylogenomics; phylotranscriptomics; sea slugs