Phylogenomics reveals deep relationships and diversification within phylactolaemate bryozoans


Ahmed Saadi

Post doc
Unit for Integrative Zoology, Department of Evolutionary Biology, University of Vienna

Saadi AJ1, Bibermair J1, Kocot KM2., Hirose M3, Calcino A1, Baranyi C1, Chaichana R, Wood TS4, Schwaha T1
1- Department of Evolutionary Biology, Unit for Integrative Zoology, University of Vienna, Djerassiplatz 1, A-1030 Vienna, Austria.
2- Department of Biological Sciences and Alabama Museum of Natural History, University of Alabama, Tuscaloosa, Alabama, 35487, USA. 
3- Department of Natural History Sciences, Graduate School of Science, Hokkaido University, N10 W8, Kita-ku, Sapporo 060-0810, Japan.
4- Department of Biological Sciences, Wright State University, Dayton, OH 45435 USA.


Bryozoans are aquatic, mostly sessile colonial invertebrates that inhabit all kinds of aquatic ecosystems. Extant bryozoan species fall into one of three classes with Phylactolaemata being the only exclusively freshwater clade. The phylogenetic relationships within the class Phylactolaemata have long been controversial owing to the absence of obvious characteristics that reflect evolutionary relationships. Previous molecular evolutionary studies based on a single gene or a combination of few loci have failed to fully resolve the interfamilial relationships of phylactolaemates. Here, we present the first phylogenomic analysis of the Phylactolaemata using transcriptomic data combined with dense taxon sampling to better resolve the interrelationships and to estimate divergence time within this class. Our results fully resolve interrelationships among phylactolaemate families with strong support. Our results show a principal division between Stephanellidae and a clade comprising all other phylactolaemate groups followed by a subsequent division within this latter clade between Lophopodidae and the remaining phylactolaemate families. The Plumatellidae is a polyphyletic family with Plumatella fruticosa clearly falling outside Plumatellidae as previous investigations had suggested. Our preliminary results indicate that the most common ancestor of the Phylactolaemata appeared in the early Cambrian (534 Ma) and the oldest lineage of the phylactolaemate tree (Stephanellidae) appeared in the late Ordovician (443 Ma). The diversification of the largest phylactolaemate family (Plumatellidae) began at the early Permian (276 Ma) with most of the plumatellid lineages diverging in the late Cretaceous and in the Paleogene, highlighting post-extinction diversification.