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Abstract

Intermittent populations of cyclic parthenogens such as Daphnia magna (Crustacea: Cladocera) have a population genetic structure that is characterised by recurrent bouts of sexual mixis, which theoretically yields a wide array of genotypes, and is quite different from that found in permanent pond populations. The Daphnia magna population in an intermittent, large shallow lake in Northern Germany has two major periods of sexual reproduction during the year, usually in May and late summer before the pond is drained. Assuming random mating during sexual reproduction, one might expect numerous clones to emerge from the ephippial hatchling pool. However, the multi-locus genotype composition was not significantly different among the ephippial hatchlings in both spring 1995 and 1996, and the adult populations in summer 1994, 1995 or 1996.