Elevated spring testosterone increases parasite intensity in male red grouse

Research output: Contribution to journalArticle

53 Citations (Scopus)

Abstract

The expression of testosterone-dependent sexual traits might signal the ability of their bearers to cope with parasite infections. According to the immunocompetence handicap hypothesis (IHH), such signals would be honest because physiological costs of testosterone, such as a reduced ability to control parasite infections, would prevent cheating. We tested whether testosterone would affect the outcome of a standardized parasite challenge in red grouse, using a main parasite of the species, the nematode Trichostrongylus tenuis. We caught males in spring, removed their nematode parasites, and implanted them with testosterone or empty implants, as controls. After 1 month, they were reinfected with a standard dose of infective T. tenuis parasites. When challenged, testosterone males had relatively less globulin relative to albumin plasma proteins than control males, an indication that they had experienced increased physiological stress. Testosterone-treated males had significantly more T. tenuis parasites than controls in the next autumn and also had more coccidia and lost more weight than controls. Testosterone-treated males nevertheless benefited from their elevated spring testosterone: they had bigger sexual ornaments than controls both in spring and autumn, and they tended to have a higher pairing and breeding success than controls. Our results supported the IHH in showing that elevated testosterone impaired the ability of males to cope with a standardized challenge by a dominant parasite. Testosterone thus plays a key role in mediating trade-offs between reproductive activities and parasite defense, and testosterone-dependent comb size might honestly signal the ability of red grouse to control T. tenuis infection.

Original languageEnglish
Pages (from-to)117-125
Number of pages9
JournalBehavioral Ecology
Volume17
DOIs
Publication statusPublished - 2006

Keywords

  • coccidia
  • immunocompetence
  • parasite
  • red grouse
  • sexual selection
  • testosterone
  • trade-off
  • Trichostrongylus tenuis
  • LAGOPUS-LAGOPUS-SCOTICUS
  • IMMUNOCOMPETENCE-HANDICAP HYPOTHESIS
  • THREADWORMS TRICHOSTRONGYLUS-TENUIS
  • AUTUMN TERRITORIAL BEHAVIOR
  • MALE ROCK PTARMIGAN
  • SEXUAL-SELECTION
  • IMMUNE FUNCTION
  • POPULATION-DYNAMICS
  • PASSER-DOMESTICUS
  • GONADAL-STEROIDS

Cite this

Elevated spring testosterone increases parasite intensity in male red grouse. / Mougeot, F ; Redpath, S M ; Piertney, S B .

In: Behavioral Ecology, Vol. 17, 2006, p. 117-125.

Research output: Contribution to journalArticle

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T1 - Elevated spring testosterone increases parasite intensity in male red grouse

AU - Mougeot, F

AU - Redpath, S M

AU - Piertney, S B

PY - 2006

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N2 - The expression of testosterone-dependent sexual traits might signal the ability of their bearers to cope with parasite infections. According to the immunocompetence handicap hypothesis (IHH), such signals would be honest because physiological costs of testosterone, such as a reduced ability to control parasite infections, would prevent cheating. We tested whether testosterone would affect the outcome of a standardized parasite challenge in red grouse, using a main parasite of the species, the nematode Trichostrongylus tenuis. We caught males in spring, removed their nematode parasites, and implanted them with testosterone or empty implants, as controls. After 1 month, they were reinfected with a standard dose of infective T. tenuis parasites. When challenged, testosterone males had relatively less globulin relative to albumin plasma proteins than control males, an indication that they had experienced increased physiological stress. Testosterone-treated males had significantly more T. tenuis parasites than controls in the next autumn and also had more coccidia and lost more weight than controls. Testosterone-treated males nevertheless benefited from their elevated spring testosterone: they had bigger sexual ornaments than controls both in spring and autumn, and they tended to have a higher pairing and breeding success than controls. Our results supported the IHH in showing that elevated testosterone impaired the ability of males to cope with a standardized challenge by a dominant parasite. Testosterone thus plays a key role in mediating trade-offs between reproductive activities and parasite defense, and testosterone-dependent comb size might honestly signal the ability of red grouse to control T. tenuis infection.

AB - The expression of testosterone-dependent sexual traits might signal the ability of their bearers to cope with parasite infections. According to the immunocompetence handicap hypothesis (IHH), such signals would be honest because physiological costs of testosterone, such as a reduced ability to control parasite infections, would prevent cheating. We tested whether testosterone would affect the outcome of a standardized parasite challenge in red grouse, using a main parasite of the species, the nematode Trichostrongylus tenuis. We caught males in spring, removed their nematode parasites, and implanted them with testosterone or empty implants, as controls. After 1 month, they were reinfected with a standard dose of infective T. tenuis parasites. When challenged, testosterone males had relatively less globulin relative to albumin plasma proteins than control males, an indication that they had experienced increased physiological stress. Testosterone-treated males had significantly more T. tenuis parasites than controls in the next autumn and also had more coccidia and lost more weight than controls. Testosterone-treated males nevertheless benefited from their elevated spring testosterone: they had bigger sexual ornaments than controls both in spring and autumn, and they tended to have a higher pairing and breeding success than controls. Our results supported the IHH in showing that elevated testosterone impaired the ability of males to cope with a standardized challenge by a dominant parasite. Testosterone thus plays a key role in mediating trade-offs between reproductive activities and parasite defense, and testosterone-dependent comb size might honestly signal the ability of red grouse to control T. tenuis infection.

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KW - immunocompetence

KW - parasite

KW - red grouse

KW - sexual selection

KW - testosterone

KW - trade-off

KW - Trichostrongylus tenuis

KW - LAGOPUS-LAGOPUS-SCOTICUS

KW - IMMUNOCOMPETENCE-HANDICAP HYPOTHESIS

KW - THREADWORMS TRICHOSTRONGYLUS-TENUIS

KW - AUTUMN TERRITORIAL BEHAVIOR

KW - MALE ROCK PTARMIGAN

KW - SEXUAL-SELECTION

KW - IMMUNE FUNCTION

KW - POPULATION-DYNAMICS

KW - PASSER-DOMESTICUS

KW - GONADAL-STEROIDS

U2 - 10.1093/beheco/arj005

DO - 10.1093/beheco/arj005

M3 - Article

VL - 17

SP - 117

EP - 125

JO - Behavioral Ecology

JF - Behavioral Ecology

SN - 1045-2249

ER -