Sex and testosterone effects on growth, immunity and melanin coloration of nestling Eurasian kestrels: é

Juan A. Fargallo, Jesus Martinez-Padilla, Adolfo Toledano-Díaz, Julián Santiago-Moreno, José A. Dávila

Research output: Contribution to journalArticle

66 Citations (Scopus)

Abstract

Sex differences in testosterone levels and sex-biased sensitivity to testosterone are the basis of some ideas postulated to account for sex-linked environmental vulnerability during early life. However, sex variation in circulating testosterone levels has been scarcely explored and never manipulated at post-natal stages of birds in the wild.

We measured and experimentally increased circulating testosterone levels in nestling Eurasian kestrels Falco tinnunculus. We investigated, possible sexual differences in testosterone levels and the effect of this hormone on growth (body mass and tarsus length) and cell-mediated immunity in males and females. We also explored testosterone effects on rump coloration, a highly variable melanin-based trait in male nestlings. We analysed data on circulating testosterone levels of nestlings in 15 additional bird species.

Increased levels of testosterone tended to negatively affect body condition, reduced cell-mediated immune responses in male and female nestlings and also diminished the expression of grey rump coloration in male nestlings. No sex differences were observed in testosterone levels in either control or increased testosterone group nestlings, and no interactions were found between sex and treatment. However, male nestlings showed a lower cell-mediated immune response than females in both groups.

Our results indicate first, that a high level of testosterone in all nestlings in a brood entails costs, at least in terms of immunity, coloration and probably growth. Secondly, sex differences in post-natal cell-mediated immunity, and consequently in the capacity to prevent diseases, cannot be explained by sex differences in circulating testosterone levels. Finally, by comparing published data at an interspecific level, contradictory sex patterns in circulating testosterone levels have been found, supporting the idea that circulating testosterone might not be a proximate factor causing sex-dependent vulnerability in bird species.

Original languageEnglish
Pages (from-to)201-209
Number of pages9
JournalJournal of Animal Ecology
Volume76
Issue number1
Early online date11 Dec 2006
DOIs
Publication statusPublished - Jan 2007

Keywords

  • androgen
  • immunocompetence
  • rump
  • sex allocation
  • cell-mediated-immunity
  • headed gull chicks
  • great tit nestlings
  • sparrows passer-domesticus
  • yolk testosterone
  • challenge hypothesis
  • plumage coloration
  • begging behavior
  • singing behavior
  • gonadal-steroids

Cite this

Fargallo, J. A., Martinez-Padilla, J., Toledano-Díaz, A., Santiago-Moreno, J., & Dávila, J. A. (2007). Sex and testosterone effects on growth, immunity and melanin coloration of nestling Eurasian kestrels: é. Journal of Animal Ecology, 76(1), 201-209. https://doi.org/10.1111/j.1365-2656.2006.01193.x

Sex and testosterone effects on growth, immunity and melanin coloration of nestling Eurasian kestrels : é. / Fargallo, Juan A.; Martinez-Padilla, Jesus; Toledano-Díaz, Adolfo; Santiago-Moreno, Julián; Dávila, José A.

In: Journal of Animal Ecology, Vol. 76, No. 1, 01.2007, p. 201-209.

Research output: Contribution to journalArticle

Fargallo, JA, Martinez-Padilla, J, Toledano-Díaz, A, Santiago-Moreno, J & Dávila, JA 2007, 'Sex and testosterone effects on growth, immunity and melanin coloration of nestling Eurasian kestrels: é' Journal of Animal Ecology, vol. 76, no. 1, pp. 201-209. https://doi.org/10.1111/j.1365-2656.2006.01193.x
Fargallo, Juan A. ; Martinez-Padilla, Jesus ; Toledano-Díaz, Adolfo ; Santiago-Moreno, Julián ; Dávila, José A. / Sex and testosterone effects on growth, immunity and melanin coloration of nestling Eurasian kestrels : é. In: Journal of Animal Ecology. 2007 ; Vol. 76, No. 1. pp. 201-209.
@article{7b72d3f047314c088e56385f965ba921,
title = "Sex and testosterone effects on growth, immunity and melanin coloration of nestling Eurasian kestrels: {\'e}",
abstract = "Sex differences in testosterone levels and sex-biased sensitivity to testosterone are the basis of some ideas postulated to account for sex-linked environmental vulnerability during early life. However, sex variation in circulating testosterone levels has been scarcely explored and never manipulated at post-natal stages of birds in the wild.We measured and experimentally increased circulating testosterone levels in nestling Eurasian kestrels Falco tinnunculus. We investigated, possible sexual differences in testosterone levels and the effect of this hormone on growth (body mass and tarsus length) and cell-mediated immunity in males and females. We also explored testosterone effects on rump coloration, a highly variable melanin-based trait in male nestlings. We analysed data on circulating testosterone levels of nestlings in 15 additional bird species.Increased levels of testosterone tended to negatively affect body condition, reduced cell-mediated immune responses in male and female nestlings and also diminished the expression of grey rump coloration in male nestlings. No sex differences were observed in testosterone levels in either control or increased testosterone group nestlings, and no interactions were found between sex and treatment. However, male nestlings showed a lower cell-mediated immune response than females in both groups.Our results indicate first, that a high level of testosterone in all nestlings in a brood entails costs, at least in terms of immunity, coloration and probably growth. Secondly, sex differences in post-natal cell-mediated immunity, and consequently in the capacity to prevent diseases, cannot be explained by sex differences in circulating testosterone levels. Finally, by comparing published data at an interspecific level, contradictory sex patterns in circulating testosterone levels have been found, supporting the idea that circulating testosterone might not be a proximate factor causing sex-dependent vulnerability in bird species.",
keywords = "androgen, immunocompetence, rump, sex allocation, cell-mediated-immunity, headed gull chicks, great tit nestlings, sparrows passer-domesticus, yolk testosterone, challenge hypothesis, plumage coloration, begging behavior, singing behavior, gonadal-steroids",
author = "Fargallo, {Juan A.} and Jesus Martinez-Padilla and Adolfo Toledano-D{\'i}az and Juli{\'a}n Santiago-Moreno and D{\'a}vila, {Jos{\'e} A.}",
year = "2007",
month = "1",
doi = "10.1111/j.1365-2656.2006.01193.x",
language = "English",
volume = "76",
pages = "201--209",
journal = "Journal of Animal Ecology",
issn = "0021-8790",
publisher = "BLACKWELL PUBLISHING LTD",
number = "1",

}

TY - JOUR

T1 - Sex and testosterone effects on growth, immunity and melanin coloration of nestling Eurasian kestrels

T2 - é

AU - Fargallo, Juan A.

AU - Martinez-Padilla, Jesus

AU - Toledano-Díaz, Adolfo

AU - Santiago-Moreno, Julián

AU - Dávila, José A.

PY - 2007/1

Y1 - 2007/1

N2 - Sex differences in testosterone levels and sex-biased sensitivity to testosterone are the basis of some ideas postulated to account for sex-linked environmental vulnerability during early life. However, sex variation in circulating testosterone levels has been scarcely explored and never manipulated at post-natal stages of birds in the wild.We measured and experimentally increased circulating testosterone levels in nestling Eurasian kestrels Falco tinnunculus. We investigated, possible sexual differences in testosterone levels and the effect of this hormone on growth (body mass and tarsus length) and cell-mediated immunity in males and females. We also explored testosterone effects on rump coloration, a highly variable melanin-based trait in male nestlings. We analysed data on circulating testosterone levels of nestlings in 15 additional bird species.Increased levels of testosterone tended to negatively affect body condition, reduced cell-mediated immune responses in male and female nestlings and also diminished the expression of grey rump coloration in male nestlings. No sex differences were observed in testosterone levels in either control or increased testosterone group nestlings, and no interactions were found between sex and treatment. However, male nestlings showed a lower cell-mediated immune response than females in both groups.Our results indicate first, that a high level of testosterone in all nestlings in a brood entails costs, at least in terms of immunity, coloration and probably growth. Secondly, sex differences in post-natal cell-mediated immunity, and consequently in the capacity to prevent diseases, cannot be explained by sex differences in circulating testosterone levels. Finally, by comparing published data at an interspecific level, contradictory sex patterns in circulating testosterone levels have been found, supporting the idea that circulating testosterone might not be a proximate factor causing sex-dependent vulnerability in bird species.

AB - Sex differences in testosterone levels and sex-biased sensitivity to testosterone are the basis of some ideas postulated to account for sex-linked environmental vulnerability during early life. However, sex variation in circulating testosterone levels has been scarcely explored and never manipulated at post-natal stages of birds in the wild.We measured and experimentally increased circulating testosterone levels in nestling Eurasian kestrels Falco tinnunculus. We investigated, possible sexual differences in testosterone levels and the effect of this hormone on growth (body mass and tarsus length) and cell-mediated immunity in males and females. We also explored testosterone effects on rump coloration, a highly variable melanin-based trait in male nestlings. We analysed data on circulating testosterone levels of nestlings in 15 additional bird species.Increased levels of testosterone tended to negatively affect body condition, reduced cell-mediated immune responses in male and female nestlings and also diminished the expression of grey rump coloration in male nestlings. No sex differences were observed in testosterone levels in either control or increased testosterone group nestlings, and no interactions were found between sex and treatment. However, male nestlings showed a lower cell-mediated immune response than females in both groups.Our results indicate first, that a high level of testosterone in all nestlings in a brood entails costs, at least in terms of immunity, coloration and probably growth. Secondly, sex differences in post-natal cell-mediated immunity, and consequently in the capacity to prevent diseases, cannot be explained by sex differences in circulating testosterone levels. Finally, by comparing published data at an interspecific level, contradictory sex patterns in circulating testosterone levels have been found, supporting the idea that circulating testosterone might not be a proximate factor causing sex-dependent vulnerability in bird species.

KW - androgen

KW - immunocompetence

KW - rump

KW - sex allocation

KW - cell-mediated-immunity

KW - headed gull chicks

KW - great tit nestlings

KW - sparrows passer-domesticus

KW - yolk testosterone

KW - challenge hypothesis

KW - plumage coloration

KW - begging behavior

KW - singing behavior

KW - gonadal-steroids

U2 - 10.1111/j.1365-2656.2006.01193.x

DO - 10.1111/j.1365-2656.2006.01193.x

M3 - Article

VL - 76

SP - 201

EP - 209

JO - Journal of Animal Ecology

JF - Journal of Animal Ecology

SN - 0021-8790

IS - 1

ER -