Department Evolutionary Ecology
The department has three main research areas:
(1) The evolution of sex and mate choice. The widespread occurrence of sexual reproduction is still an unresolved problem in evolutionary biology. Both sexual reproduction and mate choice may be strategies in the co-evolutionary arms race between hosts and parasites. With the model organism three-spined stickleback we study with methods from immunology, immuno-genetics, molecular biology, parasitology, behavioural ecology and population/field ecology whether mate choice continuously optimises the resistance of the offspring against ever changing natural parasites in lab and field experiments. We further study whether this process can maintain the enormous polymorphism of the MHC-immunogenes of vertebrates through a process called negative-frequency-dependent selection. With its pleiotropic role in parasite resistance and mate choice the MHC provides an exceptional tool to study host-parasite co-evolution and ultimately understand the maintenance of sexual reproduction. Based on field surveys and lab experiments, we investigate the evolution of MHC genes under parasite-mediated selection. Furthermore, because they occur in rivers, lakes and the Baltic sea, sticklebacks offer an intriguing opportunity to investigate immuno-genetic local adaptation and the role of MHC in speciation.
(2) The evolution of complex parasite life-cycles. Many parasites, including some of medical and veterinary importance, use several hosts within their life cycle. This life style is an evolutionary paradox, because the likelihood of completing a life cycle presumably decreases as it becomes more complex. Why then do some parasites use multiple hosts when a direct, one-host life cycle would be easier to complete? Moreover, once parasites have adopted a complex life cycle, how do they maximize their fitness? These and related questions are being addressed using the tapeworm Schistocephalus solidus as a model system.
(3) The evolution of cooperation. The problem of sustaining a public resource that everybody is free to overuse emerges in many social dilemmas. We obviously overuse public goods, e.g., by over fishing oceans, driving pension and health insurance systems to bankrupt or risking the collapse of the global climate through unlimited use of fossil energy. These are showpieces of the ‘tragedy of the commons’, for which Hardin envisaged only inevitable breakdown. Public goods experiments, i.e. the experimental paradigm to study such problems, usually confirm that the collective benefit will not be produced. Because individuals and countries often participate in several social games simultaneously, the interaction of these games may provide a sophisticated way by which to maintain the public resource. In collaboration with the MPI for Meteorology we applied this approach to test whether humans are willing to invest in sustaining the global climate and found surprising results.