, Volume 442, Issue 1, pp 145–156

Intersex and male development in Daphnia magna

  • Suzanne E. Mitchell

DOI: 10.1023/A:1017564105942

Cite this article as:
Mitchell, S.E. Hydrobiologia (2001) 442: 145. doi:10.1023/A:1017564105942


Sex induction is environmentally stimulated in Daphnia and involves a cue-dependent response for sex determination. Somatic growth was shown to be similar in males and females during juvenile instars, but divergent due to a reduction in male somatic growth, at about the time that females produce ovaries. At this time, males appeared morphologically adult with respect to secondary sex characteristics. Intersex was rare and is unlikely to be important in natural populations. Intersex could be induced in both sexes, and observed more frequently after longer exposure to high temperature, or in the second generation following a temperature change. This indicates an impact on the ability of mothers to determine the sex of the offspring. It may be possible to use intersex characteristics for manipulative investigation of sex-determination mechanisms in Daphnia. Although sex-determination is initiated before birth, intersex occurrence suggests that development of male characters requires an additional process, probably involving hormone activity, during juvenile development and maturation.

sex-determinationDaphniasex intergrades

Copyright information

© Kluwer Academic Publishers 2001

Authors and Affiliations

  • Suzanne E. Mitchell
    • 1
  1. 1.Max Planck Institute for LimnologyPlönGermany
  2. 2.Institute for Cell, Animal and Population BiologyUniversity of EdinburghEdinburghScotland