Wegner, Mathias

Research

Host-parasite coevolution
Arms races between hosts and parasites can have profound effects on the genetics of both host and parasite populations. One resulting effect is the maintenance of genetic diversity, the extreme polymorphism of vertebrate Major Histocompatibility Complex (MHC) genes, illustrated, for example, by my work on the MHC of three spined sticklebacks Gasterosteus aculeatus, best captures this aspect. Selection exerted by parasites can also select for linkage disequilibrium between epistatically interacting host genes. By creating negative linkage disequilibria, parasitism will select for recombination between host defence genes, and might ultimately explain the maintenance of sexual reproduction despite its two-fold cost (Red Queen hypothesis). My current work with Camillo Berenos and Niels Kerstes on Red Flour beetles Tribolium castaneum focuses on the dynamics of linkage disequilibria and the underlying role of meiotic recombination in creating new genotypic variants with higher resistance/tolerance to infection. Here, we mainly apply experimental evolution protocols to observe rapid evolutionary responses predicted by theory. The two outcomes of parasitism, i.e. maintenance of genetic variation and selection for recombination, are also tightly connected. Islands of linkage disequilibrium with interspersed recombination hotspots, for example, characterize the human MHC. I consider the tight connection between these two processes to be a highly interesting field of research that I would like to explore with my future research.

Olfactory mate choice
MHC genes are one crucial part of the evolutionary big bang of the adaptive immune system. Due to somatic recombination of T-cell receptor and antibodies, nearly all protein motifs can be targeted by an immune response – including self tissue. To avoid autoimmunity, T cell populations have to be restricted by MHC genes. However, it is unlikely that both classes of genes originated in parallel. Hence, it is likely that the quality control by MHC genes originated earlier during evolution and served different purposes. For MHC genes, a well established function exists as a mediator of mate choice to maximize or optimize genetic diversity in offspring. Together with the technology-transfer company, basisnote AG , I further explore the mechanistic basis as well as the consequences of olfactory mate choice in humans.
see feature in ETH-life

short CV

Publications