Genotype-dependant daytime vertical distribution of Daphnia magna in a shallow pond.

The daytime vertical distribution of Daphnia magna STRAus genotypes, characterized by differences at two enzyme loci (Got and Pgi), was analysed in a shallow pond. Though all genotypes tended to occur predominantly in the lower half of the water column, we observed significant differences in the vertical distribution of genotypes marked by differences at the Got locus. Our results indicate that, in shallow water bodies too, the vertical distribution of zooplankton is not merely random, and that vertical distribution and migration patterns may be genotype-dependent in such small-scale systems.