Marianne C. Imhof, Ph.D.


I studied Biology (Zoology/Animal Behaviour, Anthropology) at the University of Vienna. My Masters was done at the Konrad Lorenz Forschungsstelle in Grünau, which is a field station of the Viennese Department of Animal Behaviour. Since 1996 I am working in Christian Schlötterer`s Lab at the Institute for Animal Breeding and Genetics, University of Veterinary Medicine, Vienna.

Masters Thesis:    Faces of Greylag Geese, morphometry and behaviour

PhD Thesis:         Factors influencing microsatellite instability

Current Research


Adaptive mutations in E. coli

Advantageous mutations lead to a higher fitness and hence per definition to more offspring of their bearer. Because of their pivotal role in adaptation processes there has been a long-standing interest to study the nature of beneficial mutations. Unfortunately, these positive mutations are rare and thus difficult to study. We have developed a new marker system, which allows us to systematically study beneficial mutations in E. coli.
Long-term experiments demonstrated that several beneficial mutations occur during the propagation of E. coli. Our highly polymorphic, microsatellite based marker system allows the discrimination of different allelic lineages in a growing bacterial culture. The microsatellite marker mutates during the propagation of the culture leading to high allelic diversity in the E. coli population. Once a beneficial mutation arises, it will spread through the population. This spread results in a simultaneous spread of a given microsatellite allele associated to the cell carrying the advantageous mutation. Hence, the occurrence of a beneficial mutation can be detected by a temporary fixation of one microsatellite allele. The advantage of the use of our marker system is that we can identify the cell bearing the beneficial mutation as well as the time point when the beneficial mutation spreads through the population.

Sperm Competition

Multiple paternity and sperm competition in Drosophila melanogaster has been of continuous interest in evolutionary biology. Recently, it has been shown that seminal fluid transferred to the female significantly reduces female viability. Hence, females are expected to keep the number of matings to a minimum. However, if multiple matings represent a potential benefit for females, multiple mating may be beneficial under certain circumstances. Therefore, we used highly polymorphic microsatellite markers to determine the minimum number of mates of females collected in the wild. Our results showed that the females had mated more often than expected. The costs of multiple copulations for the female should be lower than the advantages of multiple paternity for the progeny of one female idividual. These results may be interpreted as a form of coevolution of the sexes.


Imhof M, Harr B, Brem G, Schlötterer C (1998): Multiple mating in wild Drosophilamelanogasterrevisited by microsatellite analysis. Molecular Ecology 7:915-917

Bachtrog D, Imhof M, Agis M & Schlötterer C (2000): Microsatellite Variability Differs Between Dinucleotide Repeat Motifs-Evidence from Drosophila melanogaster.Molecular Biological Evolution 17(9):1277-1285

M. Imhof & C. Schlötterer (2001): Fitness effects of advantageous mutations in evolving E. colipopulations. PNAS 98/3, 1113-17

M. Imhof & C. Schlötterer: Fertility (F) factor induced genomic instability in dividing E. coli cells, submitted


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