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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

In English

Författare

Summary, in 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.

Publiceringsår

2007

Språk

Engelska

Sidor

509-519

Publikation/Tidskrift/Serie

American Naturalist

Volym

170

Issue

4

Dokumenttyp

Artikel i tidskrift

Förlag

University of Chicago Press

Ämne

  • Biological Sciences
  • Ecology

Nyckelord

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

Status

Published

Forskningsgrupp

  • Molecular Ecology and Evolution Lab

ISBN/ISSN/Övrigt

  • ISSN: 0003-0147