Molecular paleobiology of lithistid sponges - reconstructing patterns and timing of diversification

• Applicants: Dr. Dirk Erpenbeck; Professor Dr. Gert Wörheide
• Subject Area: Palaeontology
• Term: from 2014 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 258786575

Sponges, a group of non-bilaterian animals with assumed origins in the late Proterozoic, are important for our understanding of early animal evolution due to their early branching in the animal tree of life. However, the relatively scarce fossil record of certain key-groups (e.g., keratose sponges) and the difficulties in establishing phylogenetic relationships of fossil and extant taxa with morphology alone hampers a more complete understanding of early animal- and sponge evolution. More efforts need to be devoted to investigate patterns of diversification and timing of the separation of sponge lineages, particularly demosponges. "Lithistid" sponges are a polyphyletic group within Demospongiae with yet uncertain relationships to the other lineages. Their extensive fossil record, however, due to their rigid skeleton of interlocking siliceous skeletal elements (desmas), makes them prime targets for studies that combine molecular systematics with the fossil record. Here we propose to assess the phylogenetic relationships of lithistid demosponges using such a molecular palaeobiological approach to (1) establish a robust phylogenetic framework to position extant desma-bearing sponges within Demospongiae and (2) use unequivocally identifiable fossils as calibrations for relaxed molecular clock estimations to facilitate the reconstruction of time and radiation pattern of demosponge lineages. Results of this project will further our understanding of the evolution and phylogenetic relationships of this palaeontologically important group of animals.

• DFG Programme: Research Grants
• International Connection: Poland, Sweden
• Participating Persons: Dr. Martin Dohrmann; Professor Dr. Andrzej Pisera; Dr. Astrid Schuster