Clonal erosion in overwintering populations of Daphnia pulex

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Daphnia have a dual reproduction mode including parthenogenetic reproduction during favourable environmental conditions as well as sexual reproduction when environmental conditions deteriorate e.g. in the fall. Two different overwintering strategies exist in Daphnia: Daphnia can invest in survival and overwinter as parthenogenetic adults and/or they can invest in reproduction and overwinter as sexually produced, diapause eggs (ephippia). Both strategies co-exist in Daphnia pulex populations from lakes that provide suitable conditions for survival during winter (= do not freeze all the way to the bottom). In this project I want to investigate the seasonal fluctuations of the clonal composition over 24 months in such a Daphnia pulex field population. I am interested in whether there is clonal erosion due to selection or random drift during the winter months and if the genotypic variability is restored during spring from the resting egg bank. I want to investigate whether different clones of Daphnia invest differently in survival and reproduction and may be selected for either strategy. This project focuses on the analyses of genotypic diversity, but from combining the population genetic results with ecophysiological data I expect synergisms and a deeper insight into the evolution of alternative survival- and reproductive strategies.