| 1991-1992 | Consultant, Dynamics of Computation Group, Xerox Palo Alto Research Center, CA |
| 1992-1994 | Research Assistant, Theoretical Ecology Group, Research Center Jülich |
| 1994-1995 | Research Scholar, Neurodynamics Group, Research Center Jülich, Germany |
| 1995 | Research Scholar, Institute of Evolutionary and Ecological Sciences, Leiden University |
| 1996 | Research Fellow, Institute for Advanced Study, Wissenschaftskolleg zu Berlin, Germany |
| 1996-2001 | Project Coordinator, Adaptive Dynamics Network, International Institute for Applied Systems Analysis, Laxenburg |
| 2001-2004 | Project Leader, Adaptive Dynamics Network, International Institute for Applied Systems Analysis, Laxenburg |
| 2004-2005 | Program Leader, Adaptive Dynamics Network, International Institute for Applied Systems Analysis, Laxenburg |
| 2006-2013 | Program Leader, Evolution and Ecology Program, International Institute for Applied Systems Analysis, Laxenburg |
| since 2014 | Program Director, Evolution and Ecology Program, International Institute for Applied Systems Analysis, Laxenburg |
