Figure 1.

Parthenogenetic Daphnia. Individuals of Daphnia pulex derived from a parthenogenetic line kept in a flow-through system that generates constant environmental conditions. The animals are highly synchronized, both with respect to size and the number of eggs they produce. This demonstrates the excellent experimental accessibility of Daphnia as a fresh water ecological model system (Reproduced by kind permission of Winfried Lampert, taken from 'Daphnia: Development of a Model Organism in Ecology and Evolution' [13]).