Linking social environment, endocrinology and behaviour across generations: maternal effects in Japanese quail (#48)
The social environment of breeding birds affects circulating hormone levels and deposition of hormones to the yolk. In turn, yolk hormones influence offspring development. By studying the effects of the social environment on hormones and development across four generations of Japanese quail (Coturnix japonica), we aim to understand in which way the social environment induces maternal effects, potentially preparing the offspring for their future environment.
We investigated whether pair vs. group living affects body mass, plasma hormone levels and the physiological response to challenges (corticosterone after restraint, GnRH stimulation of testosterone production) in breeding females. Additionally, we measured the effects on egg mass and yolk testosterone concentrations as mediators of maternal effects, chick development, and their behavioural responses in a tonic immobility and emergence test. As adults, F1 females were placed in social conditions either matched or mismatched to that of their mothers, to investigate the potentially adaptive consequences of socially induced maternal effects. We also studied F2 and F3 offspring, all group-housed, enabling us to see whether maternal effects persist across generations.
We show that social conditions affected females’ testosterone levels, but not their body mass or plasma corticosterone concentrations. Average yolk testosterone concentrations were not influenced by the social environment. However, social treatment modified the relationship between egg mass and yolk testosterone concentration, and chick growth in relation to egg mass. Maternal social conditions did not influence offspring tonic immobility response, nor boldness and exploration behaviour in the emergence test, which is in line with the finding that maternal plasma corticosterone and average yolk testosterone concentrations were not affected. Surprisingly though, maternal treatment modulated the F1 offspring’s stress response as adults, irrespective of their own social conditions. In conclusion, our study demonstrates that the social environment induces maternal effects, the consequences of which seem to be dependent of the offspring’s life stage.