Cleavage Patterns and Gastrulation As Complex Characters for Phylogenetic Inferences in the Metazoa: The Early Development of Rotifera (II) and Kinorhyncha

The analysis of early ontogenetic stages can contribute to the resolution of metazoan phylogenetic relationships. Here we address two questions. One is whether the Rotifera show spiral cleavage or traces thereof as is suggested by the Lophotrochozoa/Spiralia hypothesis or whether they show a cleavage type which is more related to that of Cycloneuralia. The second question deals with the early development of Kinorhyncha and its contribution to the reconstruction of the ancestral ecdysozoan cleavage pattern. Our knowledge about the cleavage pattern and the gastrulation of both groups is still fragmentary. To fill these gaps we want to study the early cleavage patterns, the cell lineages, the cell fates, and the gastrulation modes of representatives of Rotifera and Kinorhyncha in great detail with a variety of methods ranging from histology to 4D-microscopy. Our results will be compared with available data from the literature. In collaboration with the Deep Metazoan Phylogeny network, the developmental characters will be defined, conceptualised, fed into a comprehensive morphological data matrix, and eventually used to analyse metazoan phylogenetics.