Experimental evidence for genetic heritability of maternal hormone transfer to offspring

In many animal species, embryos are exposed to maternal hormones that affect their development. Maternal hormone transfer varies with environmental conditions of the mother and is often interpreted as being shaped by natural selection to adjust the offspring to prevailing environmental conditions. Such hormone transfer requires genetic variability which has not yet been experimentally demonstrated. Our study reports direct evidence for additive genetic variance of maternal androgens through a bi-directional selection on yolk testosterone (T) levels in Japanese quail. Lines selected for high (HET) and low (LET) egg T concentration differed in yolk levels of this androgen resulting in high realised heritability (h2 = 0.42). Correlated responses to selection on other gonadal hormones indicate that selection specifically targeted biological active androgens. Eggs of HET quail contained higher androstenedione and lower estradiol concentrations than those of LET quail, with no line difference...

在诸多动物物种中，胚胎会暴露于母体激素之中，此类激素会对胚胎发育产生影响。母体激素传递会随母体所处的环境条件发生变化，该过程通常被认为是自然选择塑造的结果，旨在让后代适配当下的环境条件。这类激素传递需要遗传变异作为基础，但此前尚未有实验证据证实这一点。本研究通过对日本鹌鹑卵黄睾酮（testosterone, T）水平开展双向选择实验，为母体雄激素的加性遗传方差（additive genetic variance）提供了直接证据。针对卵睾酮浓度高低分别选育的高睾酮选择系（HET）与低睾酮选择系（LET），其卵黄中该雄激素的水平存在显著差异，且现实遗传力较高（h² = 0.42）。对其他性腺激素的选择相关响应表明，本次选择实验精准靶向了具有生物活性的雄激素。日本鹌鹑HET系所产卵的雄烯二酮（androstenedione）浓度更高，雌二醇（estradiol）浓度更低，而两选择系之间并无其他显著差异……