Ecology & Evolution

Evolutionary rescue (together with François Blanquart, Hildegard Uecker and Florence Débarre)
In a spatially structured environment consisting of patches (all connected to each other), we computed the probability of establishment of a mutant in a heterogeneous environment. Dependent on the patch type (good or bad) the mutant is either disadvantageous (good patches) or advantageous (bad patches) when compared to the wild type. Based on this establishment probability we subsequently approximated the probability for evolutionary rescue in the situation where one patch after another deteriorate, i.e. turn from a good state to a bad state.
Publications:
The effect of habitat choice on evolutionary rescue in subdivided populations, (preprint)

Demographic noise (together with Arne Traulsen and Chaitanya Gokhale)
We studied a system with two traits with intra- and interspecific competition (stochastic competitive Lotka-Volterra) under fluctuations in population size. We were mostly interested in the impact of the four competition parameters which we interpreted in terms of an evolutionary game. We found that in order to disentangle the ecological (population size fluctuations) from the evolutionary (trait frequency dynamics) scale in this system the two traits need to be very similar, i.e. we are in the context of nearly neutral mutations.
Publications:
Fixation probabilities in populations under demographic fluctuations, Journal of Mathematical Biology (2018), 77(4), 1233-1277 (view online)
Disentangling eco-evolutionary effects on trait fixation, Theoretical Population Biology (2018), 124, 93-107 (preprint) (TPB link)

Spatial models (together with Peter Pfaffelhuber)
We studied the impact of space on a typical cooperator-defector interaction, i.e. defectors have a larger basal birth rate than cooperators and cooperators boost the birth rate (e.g. through providing a public good) of their neighbor. We found phase transitions in all dimensions and an explicit boundary in one dimension, thus showing that nearest neighbor interactions support the emergence and maintenance of cooperation.
Publication: A spatial model for selection and cooperation, Journal of Applied Probability (2017) 54 (2), 522-539. (view online)
See also my Dissertation: Phenotypic heterogeneity in bacterial populations – a mathematical study (view online)