Jana Jarczak

Research Project B2: Life history responses to changes in food quality within Daphnia populations

Changes in trophic state can impose major challenges on aquatic organisms and thus are expected to drive micro-evolutionary processes. Cyanobacterial mass developments, frequently observed during eutrophication, represent one important challenge aquatic consumers have to cope with. Cyanobacteria are of poor food quality for aquatic consumers due to morphological properties that hamper ingestion, the production of harmful secondary metabolites, and/or a deficiency in essential lipids, i.e. polyunsaturated fatty acids (PUFA) and especially sterols. Many Daphnia populations experienced long-term changes in food quantity and quality during the last decades due to eutrophication and re-oligotrophication.

I am interested in exploring micro-evolutionary changes in the adaptation to cyanobacteria food within Daphnia populations in Lake Constance. By hatching resting eggs from sediments deposited during different time periods, I will recover genotypes from past populations. The isolated Daphnia clones are used to conduct comparative life history experiments in which genotype-specific changes in the ability to cope with cyanobacteria food are investigated. The focus in these experiments is on differences in essential lipid requirements among clones.