Hausen Group

Animals are composed of multifarious types of cells, which serve highly specific functions and may form part of tissues and organs or may occur singly. In our group we are interested in the evolution of this complexity. Which cell types and organs correspond to each other in phylogenetic distinct animals? How changed the function over time and how arose novel features? Which insights can we get in the organization of ancestral forms?
 

To fulfil their specialized tasks cells show various molecular and structural adaptions and type specific sets of genes pattern their development. To trace evolution we collect integrative data from several marine invertebrates. We combine gene expression analysis with light and electron microscopic, developmental and functional studies. With this approach we obtain insights not only in the course of evolution, but also in the biology of the organisms studied.

Currently we mainly focus on the evolution and function of photoreceptor cells and eyes in marine invertebrates. The debate how animal light sensing organs emerged is nearly as old as the debate about the principle of evolution. Integrative molecular and structural work offers now the chance to decipher eye evolution on the cellular level. It became clear that most organisms have a large set of different light sensitive cells not only in eyes. Studies on their molecular physiology, their neural connectivity and the impact on animal behaviour provide new insights into the sensory biology of marine invertebrates and the relevance of light in the marine environment. Several kinds of photoreceptors can be traced back to ancient times giving insights into the evolutionary roots of animal light sensations. Obviously, some of those photoreceptors and eyes remained similar during the later course of the evolution, while others became considerably reorganized, or changed their functional context.