Maternal testosterone affects the primary sex ratio and offspring survival in zebra finches

Sex-ratio adjustment in response to local mate competition is achieved through an alteration of egg size in a haplodiploid spider mite

“…The precise mechanisms by which such control is achieved remain unclear, but studies in both mammals and birds (e.g. in macaques [15] and in zebra finches [16]) suggest that it could be mediated by the level of hormones, such as testosterone, circulating in the breeding female around the time of sex determination. In some mammalian species in which males are the heterogametic sex, testosterone concentration in females is assumed to affect the probability of egg fertilization by Y-chromosome-bearing spermatozoa [15].…”

“…In some mammalian species in which males are the heterogametic sex, testosterone concentration in females is assumed to affect the probability of egg fertilization by Y-chromosome-bearing spermatozoa [15]. In birds, in which females are the heterogametic sex, maternal concentration of testosterone is rather hypothesized to act on chromosome segregation during meiosis [16]. Some studies suggest that variations in maternal hormones are likely to be related to the social and environmental variables that have commonly been associated with offspring sex adjustments (e.g.…”

The variances of the distributions of the combinations of the sexes within mammalian litters: Notes to mark the centenary of the problem

“…Comparable results have been reported in the field vole (Helle et al 2008); rat (Nunez & Juraska 1998) and the ibex (Shargal et al 2008). Lastly a similar phenomenon has been described in birds (Alonso-Alvarez 2006) including peafowl (Pike & Petrie 2005); Zebra finch (Rutkowska & Cichon 2006) and the spotless starling (Veiga et al 2004). Sociologists of science may decide what caused the delay between the finding in Russia and its re-discovery and acceptance elsewhere (misjudged A c c e p t e d m a n u s c r i p t scepticism about Russian reports at a time not long after the fall of Lysenko?).…”

Manipulation of primary sex-ratio: an updated review

“…Meanwhile, Veiga et al (2004) showed that female spotless starlings (Sturnus unicolor), which received testosterone implants during egg formation, produced higher proportion of sons in their clutches. Similarly, female zebra finches injected with testosterone during egg laying tended to produce clutches with sex ratios skewed towards males (Rutkowska and Cichón, 2006). By contrast, von Engelhardt et al (2004) showed no effect of 17-b oestradiol injections on primary sex ratio in the same species.…”