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An experimental test of the immunocompetence handicap hypothesis in a teleost fish: 11-ketotestosterone suppresses innate immunity in three-spined sticklebacks

  • Joachim Kurtz
  • Martin Kalbe
  • Åsa Langefors
  • Dennis Hasselquist
Publishing year: 2007
Language: English
Pages: 509-519
Publication/Series: American Naturalist
Volume: 170
Issue: 4
Document type: Journal article
Publisher: University of Chicago Press

Abstract english

The immunocompetence handicap hypothesis (ICHH) provides a functional explanation for how sexual ornaments can provide honest signals of male quality. A key aspect of this hypothesis is that testosterone (T) has a bimodal effect: a higher T level enhances the expression of ornaments (increasing mating success and, ultimately, fitness); however, at the same time, it suppresses immune function. Tests of the latter assumption, which have focused mainly on aspects of adaptive immunity in birds, led to equivocal results. We performed a hormone‐implant experiment in male three‐spined sticklebacks (Gasterosteus aculeatus) to test the key assumptions of the ICHH in a fish, where the dominant circulating androgen is 11‐ketotestosterone (11kT) rather than T. Males were implanted with 11‐ketoandrostenedione, which is a natural precursor of 11kT. Each individual's circulating 11kT level, ornamentation, and immunocompetence were measured 2 weeks later. In addition, we quantified oxidative tissue damage because the ICHH has been hypothesized to work via oxidative stress. We found that the males' 11kT levels correlated positively with ornamentation but negatively with immunocompetence, in particular, measures of innate immunity. Moreover, there was a trend for fish with high 11kT levels to suffer more from oxidative stress. Thus, our data provide support for the ICHH.


  • Biological Sciences
  • Ecology
  • oxidative stress
  • innate immunity
  • immunocompetence handicap
  • 11‐ketotestosterone
  • sexual selection
  • teleost fish.


  • Molecular Ecology and Evolution Lab
  • ISSN: 0003-0147
Dennis Hasselquist
E-mail: dennis [dot] hasselquist [at] biol [dot] lu [dot] se



+46 46 222 37 08



Research group


Doctoral students and postdocs

Research fellows


Jacob Roved

PhD Students, main supervisor

PhD Students, assistant supervisor


Interview about my research in the Swedish podcast "Forskarn & jag"