Phylogenetic and functional transcriptome analyses to highlight the evolution of Cephalocarida and Branchiopoda with special focus on Cladocera (Crustacea)
Final Report Abstract
The phylogenetic relationships within Tetraconata, which comprise the paraphyletic Crustacea as well as Hexapoda, have long been debated. In particular with regards to the sister group of Hexapoda no consensus had been reached among previous studies. In this project, based on extensive phylogenomic analyses of newly generated high quality transcriptome data sets, Remipedia were identified as the most likely sister group of Hexapoda. An alternative hypothesis – Remipedia + Cephalocarida as sister group to Hexapoda – was supported in about half of the phylogenetic analyses, but could be shown to represent an artifact of long branch attraction and compositional heterogeneity. A third hypothesis, Branchiopoda + Hexapoda, which had been recovered in many previous studies, found no support. Cephalocarida and Branchiopoda together with Hexapoda and Remipedia constitute Allotriocarida, with Cephalocarida being the sister group to all other Allotriocarida. Copepoda, Malacostraca and Thecostraca form a clade (Multicrustacea) that is sister to Allotriocarida, and Ostracoda, Branchiura, Mystacocarida and (potentially) Pentastomida comprise Oligostraca. The outcome of this project provides the ideal basis for studies dealing with evolutionary transformations and the evolutionary history of tetraconatan taxa. For Branchiopoda, the most detailed phylogenomic analyses to date, recovered all main taxa as monophyletic and supported the previously proposed topology: Anostraca: (Notostraca: (Laevicaudata: (Spinicaudata: (Cyclestheria: Cladocera)))). Molecular clock analyses suggest that intercontinental dispersal, after the break-up of Gondwana, had been common and may explain the widespread distribution of several taxa, like Eocyzicus. Based on the detailed transcriptome data that is now available it will be possible to study the origin of the genomic duplications that characterize the genome of the cladoceran Daphnia.
Publications
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(2017) A Phylogenomic Solution to the Origin of Insects by Resolving Crustacean-Hexapod Relationships. Current biology : CB 27 (12) 1818-1824.e5
Schwentner, Martin; Combosch, David J.; Pakes Nelson, Joey; Giribet, Gonzalo
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2016. 'Pancrustacean phylogenomics – new insights into pancrustacean evolution from largescale transcriptome analyses' 109th Annual Meeting of the Deutschen Zoologischen Gesellschaft (DZG) in Kiel
Martin Schwentner
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2017. 'Crustraceen Phylogenie: Neue Erkenntnisse zur Evolution der Crustacea basierend auf Transkriptom Analysen', 18. Crustaceologen Tagug in Berlin
Martin Schwentner
