Projekte der Theoretischen Biologie
Density dependent polymorphisms
Population density influences many aspects of an individual's life cycle. For example, at high densities, competition for resources can be higher, but finding a mate may be easier. My research tries to reveal how individuals can be adapted to different population densities. I am especially interested in understanding the circumstances under which both high and low-density specialists can co-exist. In order to research this, I use theoretical models that describe phenotypic plasticity and genetic processes. This work is embedded in the CRC'NC^3 within which I will collaborate to apply the theoretical models to empirical data on fur seals (in collaboration with Joe Hofman) and fruit flies (in collaboration with Claudia Fricke and Laura Japke).
Interactions between bottleneck-effects and mating systems
In my project I want to look at the interaction between population bottlenecks or founder effects and mating systems. On the one hand the mating system can greatly affect a population's recovery after a bottleneck, on the other hand frequently occurring bottlenecks might shape the populations mating strategies. These processes are very important for extinction or survival of small or threatened populations. The first part of this project is in cooperation with Steven Ramm from the Department of Evolutionary Biology. We model the mating system of hermaphroditic animals. Specifically, we consider flatworms that can mate with other individuals or self-fertilize. So called 'selfing' grants reproductive assurance in case no mating partners are available, but comes at the cost of losing offspring due to inbreeding depression. Can recurrent bottlenecks lead to a system where both strategies are present with individual variation in selfing propensity? Further I want to look into mating systems with polygamy and skewed sex ratios due to temperature dependent sex determination
Eco-evolutionary feedback between genetic diversity and population sizes in variable environments
Small populations are often strongly affected by genetic drift, demographic stochasticity and often also by changing environmental conditions. My main objective is to understand: (a) how genetic variation can be maintained in populations living in temporally variable environments, (b) how much genetic variation is needed for small populations to escape extinction, and (c) what eco-evolutionary feedback can be obtained between population sizes and genetic variation. Mathematical models with fluctuations in both selection pressures and population sizes will be constructed. The model results will then be applied to suitable empirical data.
Influence of linear features on the wolf-caribou predator-prey interactions
In Canada, boreal caribou (Rangifer tarandus caribou) are threatened. A major driver of this problem appears to be wolf predation. It is already known that wolves move faster and farther on so called linear features such as roads and trails. But the effect of linear feature densities on wolf-caribou encounter rates is still unclear. I use the R package moveHMM to estimate wolf movement parameters like step length and directions. With these parameters, I then build spatial models for encounters of wolves and caribou. In that way I assess the influence of linear features on encounter rates, as well as on population dynamics.