Research
We study rapid adaptation in the waterflea Daphnia. We are following the adaptive process over different organisational levels from the genome over molecular mechanisms to the phenotype, and from the individual animal to populations and ecosystems. We have a particular focus on tracking evolution over time, in natural populations as well as in the laboratory using experimental evolution.
Our current projects address specific questions within the following research themes:
Adaptation to toxic cyanobacteria in the Daphnia longispina species complex
Toxic cyanobacteria, especially when they occur in large abundances during the so-called "algal bloom", pose a threat to aquatic ecosystems and human health. Daphnia are known to rapidly adapt to toxic cyanobacteria. This even has practical applications, as these tolerant Daphnia lines provide a means of containment of such cyanobacteria mass developments.
Here, we investigate the genomic and molecular basis of cyanobacterial tolerance in Daphnia over time and space. We analyse genomic time series and study local adaptation in organisms from habitats with different cyanobacterial loads.
Seasonal changes in a Natural Daphnia population and implications for beneficial phenotypes
We aim to establish a link between beneficial phenotypes and abundant genotypes by leveraging the knowledge about seasonal changes of abiotic and biotic factors in the lake ecosystem. In this context, the sometimes drastic seasonal changes in water temperature, oxygen and nutrient content and the resulting succession of various plankton groups are precisely characterized. It is unclear whether these changes are also reflected in rapid microevolutionary changes in population structure and/or can be intercepted by plastic responses and lead to the occurrence of so-called superclones. We address this question using the example of a natural Daphnia population in a 20-year-old gravel pit lake in the Lower Rhine region. This lake is part of the Long Term Ecological Research (LTER) Projekts REES, in which I cooperate with colleagues from the University of Cologne. In the framework of the project biotic and abiotic data for different lakes in the region will be collected regularly since 2021. Based on these data from the lake and time series of the local Daphnia population, we will characterize the genomic changes in the population over the season and match them with the corresponding environmental factors, we will analyse if specific genotypes correlate with specific environmental factors or whether the same genotypes as generalists are the most abundant fraction throughout the year.
The effect of global warming on a Daphnia population
We use experimental evolution to analyze the effect of 3°C warming on population structure and adaptation processes in experimental Daphnia populations. In contrast to studies in natural populations, this approach allows us to study the environmental changes under strictly controlled conditions and with the help of replicates. The evolution experiment is based on a natural population and maintained in replicates at two different temperature conditions (20°C and 23°C). We will study genomic time series to detect prominent genotypes and determine their phenotypic characteristics. In addition, the replicated design of the experiment to test different hypotheses related to temperature adaptation. For example, we will analyze whether parallel evolutionary processes occur at the genomic level or whether polygenic nature of temperature adaptation leads to the dominance of different genotypes in each population replicate, but with a similar level of fitness.