Webbläsaren som du använder stöds inte av denna webbplats. Alla versioner av Internet Explorer stöds inte längre, av oss eller Microsoft (läs mer här: * https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Var god och använd en modern webbläsare för att ta del av denna webbplats, som t.ex. nyaste versioner av Edge, Chrome, Firefox eller Safari osv.

Porträtt av Henrik Smith. Foto.

Henrik Smith

Professor

Porträtt av Henrik Smith. Foto.

Interfemale variation in egg yolk androgen allocation in the European starling: do high-quality females invest more?

Författare

  • KM Pilz
  • Henrik Smith
  • Maria Sandell
  • H Schwabl

Summary, in English

Androgenic hormones occur naturally in bird egg yolk and are known to enhance growth in canary and gull chicks. Gil et al. (1999, Science, 286, 126-128) have recently proposed that female allocation of androgens to eggs represents a form of costly maternal investment. This hypothesis predicts that females of high quality or high reproductive potential should invest more yolk androgens in their eggs than females of low quality or low reproductive potential. We tested these predictions by examining interfemale variation in allocation of the androgenic steroids testosterone and androstenedione to eggs in a wild population of European starlings, Sturnus vulgaris. We collected 30 full clutches of eggs and captured 22 of the females that laid these clutches for phenotypic measurements. In agreement with the hypothesis, we found that there was significant interfemale variation in yolk androgen concentrations. Furthermore, older females deposited more androstenedione and testosterone in eggs than 1-year-old females, and females laying early or large clutches deposited more testosterone in eggs than females laying late or small clutches. However, females in good body condition did not deposit more androgens in eggs than females in poor body condition. Large-yolked eggs had a higher total yolk androgen content than small-yolked eggs, but larger eggs did not have higher concentrations of yolk androgens. The results in general support the investment hypothesis of yolk androgen allocation. However, further data are needed regarding the costs of yolk androgen allocation and the effects of yolk androgens on offspring to substantiate the assumptions of the hypothesis.

Avdelning/ar

  • Biodiversity
  • Biologiska institutionen
  • Biodiversitet och bevarandevetenskap

Publiceringsår

2003

Språk

Engelska

Sidor

841-850

Publikation/Tidskrift/Serie

Animal Behaviour

Volym

65

Issue

4

Dokumenttyp

Artikel i tidskrift

Förlag

Elsevier

Ämne

  • Ecology

Aktiv

Published

Forskningsgrupp

  • Biodiversity and Conservation Science

ISBN/ISSN/Övrigt

  • ISSN: 1095-8282