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

作者：Isaksson C^*; Magrath M J L; Groothuis T G G; Komdeur J

来源：General and Comparative Endocrinology, 2010, 165(1): 97-103.

DOI：10.1016/j.ygcen.2009.06.015

• Testosterone
• Sexual size dimorphism
• Differential allocation
• Maternal effects
• Sex ratio

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.

• 出版日期2010-1-1