Andreas Hejnol

Understanding the evolution of animal biodiversity is one of the major goals in biology. How animals explored new habitats from only being confined to the marine environment and how the body plans diversified is still one of the most tremendous questions to be answered. My group studies a broad range of animal taxa using morphological and molecular tools to unravel the evolution and development of animal organ systems and the evolution of novel cell types. In the “post-genomic age” with its novel and advanced molecular tools we are able to study the connection between the genotype and the phenotype and how the interaction of genes and cells lead to the formation of a fertile adult. The “translation” of the genomic information into a living individual is realised during the process of development. Studying the development of an organism in which a single fertilised cell gives rise to a complex animal is not only fascinating, but is also one of the key processes to study to finally understand the evolution of animal diversity. Furthermore we study how developmental stages adapt to their environment. I investigate the genomic, molecular and cellular foundations of the development of diverse animal groups such as priapulids, acoels, bryozoans, brachiopods, nematomorphs, platyhelminthes, rotifers and nemerteans using the comparative evolutionary approach. My research team combines wet-lab approaches and bioinformatics to a unique ‘hybrid’ approach to gain information from a broad range of animal taxa using species that can be kept in the laboratory and some that are collected from the aquatic environment. My approach using broad taxon sampling instead of being limited to a model system adds to my unique profile and to my visibility in the field. I use advanced microscopical methods such as live 3D-timelapse microscopy (4D-microscopy) and light-sheet microscopy to study developmental processes in detail. I combine this approach with comparative genomics (de novo genome sequencing) and single-cell transcriptomics to identify evolutionary changes in the genes, their regulatory regions and their expression. We follow up on the discoveries with experimentally testing the role of genes with genome editing technologies (CRISPr-Cas9) in the organism. The molecular approaches allow to unravel the genetic framework underlying the formation of cell type diversity and different organ systems, such as the CNS (Marine Neurobiology), the alimentary canal and other mesodermal organs and finally the diversification of animals. Because taxon sampling is essential to understand evolution we implement these technologies into previously not investigated but highly informative species. Furthermore, we use the sequencing information to resolve important evolutionary relationships in the animal tree of life. Albeit 20 years of successful research has led to the higher resolution in animal relationships, several nodes have not yet been resolved. I use comparative genomics, e.g. to identify syntenies and rare genomic changes to contribute to solve the last mysteries of the placement of several animal taxa (position of Ctenophora, and Xenacoelomorpha, internal branching of Trochozoa).