No evidence for sex-specific effects of the maternal social environment on offspring development in Japanese quail (Coturnix japonica)

Abstract

The social environment of reproducing females can cause physiological changes, with consequences for reproductive investment and offspring development. These prenatal maternal effects are often found to be sex-specific and may have evolved as adaptations, maximizing fitness of male and female offspring for their future environment. Female hormone levels during reproduction are considered a potential mechanism regulating sex allocation in vertebrates: high maternal androgens have repeatedly been linked to increased investment in sons, whereas high glucocorticoid levels are usually related to increased investment in daughters. However, results are not consistent across studies and therefore still inconclusive. In Japanese quail (Coturnix japonica), we previously found that pair-housed females had higher plasma androgen levels and tended to have higher plasma corticosterone levels than group-housed females. In the current study we investigate whether these differences in maternal social environment and physiology affect offspring sex allocation and physiology. Counter to our expectations, we find no effects of the maternal social environment on offspring sex ratio, sex-specific mortality, growth, circulating androgen or corticosterone levels. Also, maternal corticosterone or androgen levels do not correlate with offspring sex ratio or mortality. The social environment during reproduction therefore does not necessarily modify sex allocation and offspring physiology, even if it causes differences in maternal physiology. We propose that maternal effects of the social environment strongly depend upon the type of social stimuli and the timing of changes in the social environment and hormones with respect to the reproductive cycle and meiosis.

Effects of the maternal and current social environment on female body mass and reproductive traits in Japanese quail (Coturnix japonica)

“…This suggests that group-housed offspring of pair-housed females increased body mass at an earlier age than offspring of grouphoused females that caught up later. There was no effect of the P0 social environment on F1 body mass before the F1 social treatment started (see also Langen et al, 2018). The positive effect on offspring body mass in the mismatched environment, at least for offspring of pair-housed females, contradicts the expectation of an adaptive maternal effect, as it does not suggest that offspring perform better in the environment matching the maternal one.…”

“…P0 females were housed in pairs (one female with one male) or in groups (three females with one male), whereas F1 females were housed in pairs (two females, one offspring from each of the P0 treatments) or in groups (four females, two offspring from each of the P0 treatments). All experiments and testing described for P0 generation females (Langen et al 2017), and for F1 generation females from hatching to the beginning of the experimental social conditions (Langen et al 2018) have been published previously. The birds were placed in the experimental social conditions at the age of 29 days in the P0 generation (see Langen et al, 2017) and 24 days in the F1 generation ( Fig.…”

“…On a weekly basis, the standard diet was supplemented with mealworms and shell grit. Langen et al, 2017Langen et al, , 2018. Scale symbols indicate when animals were weighed.…”

Density dependence of clutch size and offspring sex ratio in starling colonies

“…Despite decades of research, empirical studies addressing the Thrivers and Willard's prediction yield mixed results (Nager et al 1999, Langen et al 2018, Merkling et al 2018, Rubalcaba and Polo 2018, Geffroy and Douhard 2019, Schacht et al 2019). We propose that sex allocation strategies strongly depend on indirect social and environmental variables operating on both proximate and ultimate mechanisms of sex ratio adjustments.…”