Maternal effects obscure condition-dependent sex allocation in changing environments

Climate change increases environmental fluctuations which thereby impact population demography. Species with temperature-dependent sex determination may experience more extreme sex ratio skews, but this has not been considered in species with chromosomally-determined sex. However, anticipatory maternal effects cause lifelong physiological changes impacting sex ratios. Here we show, in mice, that more sons were born to mothers in good condition when their breeding environment matched their gestational environment, consistent with theoretical predictions, but mothers in mismatched environments have no condition sex-ratio relationship. Thus, the predicted effect of condition on sex ratio was obscured by maternal effects when the environment changed. This may explain extreme or unexpected sex ratio skews in reintroduced or translocated populations, and sex ratio skews may become more common and less predictable with accelerating environmental change.气候变化加剧环境波动，进而影响种群统计学（population demography）特征。具有温度依赖型性别决定（temperature-dependent sex determination）的物种可能会出现更极端的性别比例偏移，但这一点尚未在染色体决定性别（chromosomally-determined sex）的物种中得到考量。然而，预见性母体效应（anticipatory maternal effects）会引发终生的生理变化，进而影响性别比例。本研究在小鼠中证实：当繁殖环境与妊娠环境一致时，身体状况良好的母鼠会产下更多雄性后代，这与理论预测相符；但当环境不匹配时，母鼠身体状况与性别比例之间并无关联。因此，当环境发生改变时，母体效应会掩盖身体状况对性别比例的预期影响。这一发现或可解释重新引入或易地种群中出现的极端或异常性别比例偏移现象；随着环境变化加速，性别比例偏移现象或将愈发普遍，且更难预测。