This study aims at a reconstruction of the micro-evolution of the Daphnia population residing in Lake Ringe, Denmark. This lake has a well-documented history of habitat degradation and recovery. Through population genetic analyses directly on diapausing eggs combined with a quantitative genetic analysis on animals that hatch from diapauzing eggs recovered from different sediment depths, we will reconstruct the genetic changes that occurred through time. One of the specific hypotheses that we want to test is that diel vertical migration and diel horizontal migration are traded off against each other, in relation to the equilibrium condition of the lake (clearwater or turbid phase).