Details

Autor(en) / Beteiligte

• Isaksson, C
• Magrath, M.J.L
• Groothuis, T.G.G
• Komdeur, J

Titel

Androgens during development in a bird species with extremely sexually dimorphic growth, the brown songlark, Cinclorhamphus cruralis

Ist Teil von

• General and comparative endocrinology, 2010-01, Vol.165 (1), p.97-103

Ort / Verlag

United States: Elsevier Inc

Erscheinungsjahr

2010

Quelle

MEDLINE

Beschreibungen/Notizen

• Abstract In birds, early exposure to androgens has been shown to influence offspring growth and begging behaviour, and has been proposed as a mechanism for the development of sexual size dimorphism (SSD). Sex specific effects during development can occur due to sex-specific allocation of maternal androgens, sensitivity to, or synthesis of, androgens. In addition, maternal hormones have been suggested as a mechanism to skew brood sex ratio. This study uses one of the world’s most extreme SSD species, the brown songlark Cinclorhamphus cruralis, to investigate (1) sex-specific differences of androgens in yolk and chick plasma and (2) the relationship between androgens and sex ratio bias. The study reveals no indication of sex-specific maternal allocation, but a modest sex effect during the later stages of incubation when the embryo starts to produce its own androgens. Moreover, there was a strong seasonal sex ratio bias: female-biased early and male-biased later in the season, but yolk testosterone (T) did not show a seasonal trend. Taken together these results suggest that if androgens, from any source, have a significant role in development of SSD in this species it is most likely via sex-specific sensitivity or synthesis rather than differential maternal transfer to the egg.