Chapter

Cladocera: the Biology of Model Organisms

Volume 126 of the series Developments in Hydrobiology pp 177-185

Differential behaviour and shifts in genotype composition during the beginning of a seasonal period of diel vertical migration

  • Piet SpaakAffiliated withDepartment of Limnology, EAWAG/ETH
  • , Joop RingelbergAffiliated withNetherlands Institute of Ecology, Centre for Limnology and University of Amsterdam

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Abstract

During the first few weeks of a recurring seasonal period of diel vertical migration in Lake Maarsseveen (The Netherlands), part of the hybrid Daphnia galeata × hyalina population migrated, while another part remained in the epilimnion. In the epilimnion, 0+ perch prey upon daphnids during daytime. Gradually, the number of adult Daphnia in the epilimnion decrease until the epilimnion is nearly devoid of daphnids. The population as a whole may decrease, as in 1991, or may increase as in 1992. Genotype composition, as determined by allozyme analysis, changed substantially within a fortnight in 1992, and one genotype became dominant. Our data are in agreement with the hypothesis that predation on different genotypes (clones) occurs during the beginning of a seasonal period of diel vertical migration, though our data do not allow to exclude alternative explanations.

Key words

Daphnia 0+ perch genotypes selective predation allozyme analysis