Markus Pennerstorfer
Markus Pennerstorfer Tel: ++49 (0)30 2093 6001 |
Cleavage patterns and gastrulation as complex characters for phylogenetic inferences in the Metazoa: the early development of Phoronida and Rotatoria and its relation to spiral cleavage Cleavage patterns, cell lineages, and cell fates provide us complex spatiotemporal characters that are used for phylogenetic analyses. Nonetheless in a lot of major animal taxa our knowledge on early development is still fragmentary. Further studies are necessary to gain detailed data on as broad as possible a taxon sample for use in deep metazoan phylogeny. On the other hand new phylogenetic hypotheses need us to re-evaluate our conceptualizations of early developmental characters, but also allow us to evaluate the evolution of early development under new perspectives. One central issue in this field is the so-called spiral quartet cleavage - described in several metazoan taxa, e.g. Mollusca, Annelida, Nemerteans, Plathelminthes(?) and its relation to Lophotrochozoa. This topic is addressed by studies on two animal taxa which position in the phylogeny of Metazoa is recently in question, Phoronida and Rotifera. Most common hypotheses concerning Phoronida favor either their close relationship to Deuterostomia (Radialia hypothesis) or nest them within Spiralia (Lophotrochozoa hypothesis). In a similar manner Rotifera are considered being part of either the Nemathelminthes or the Gnathifera, a clade that is placed within Lophotrochozoa. In that way the Lophotrochozoa-hypothesis brings up the questions of what is the relation of cleavage in Phoronida and Rotifera to spiral quartet cleavage, as described for several other lophotrochozoan groups, and vice versa of the evolution of cleavage in Lophotrochozoa. Since our knowledge on the early development of Phoronida and Rotifera is fragmentary, aim of the project is to gain data on their cleavage patterns, cell lineages, and cell fates. Therefore we use a variety of methods, such as histology, fluorescent staining, confocal-laser-scanning-microscopy, single cell labeling, and 4D-microscopy. Focused on the questions of homology in early development and conceptualization of early developmental characters obtained results are compared to data in other Metazoans. On this basis we hope to contribute to the discussion on the evolution of early development in Lophotrochozoa, and where to place Phoronida and Rotifera in the phylogeny of Metazoa.
|
|---|