Data from: Matrilineal inheritance of a key mediator of prenatal maternal effects

Sex-linkage is predicted to evolve in response to sex-specific or sexually antagonistic selection. In line with this prediction, most sex-linked genes are associated with reproduction in the respective sex. In addition to traits directly involved in fertility and fecundity, mediators of maternal effects may be predisposed to evolve sex-linkage, because they indirectly affect female fitness through their effect on offspring phenotype. Here, we test for sex-linked inheritance of a key mediator of prenatal maternal effects in oviparous species, the transfer of maternally derived testosterone to the eggs. Consistent with maternal inheritance, we found that in Japanese quail (Coturnix japonica) granddaughters resemble their maternal (but not their paternal) grandmother in yolk testosterone deposition. This pattern of resemblance was not due to non-genetic priming effects of testosterone exposure during prenatal development, as an experimental manipulation of yolk testosterone levels did not affect the females' testosterone transfer to their own eggs later in life. Instead, W chromosome and/or mitochondrial variation may underlie the observed matrilineal inheritance pattern. Ultimately, the inheritance of mediators of maternal effects along the maternal line will allow for a fast and direct response to female-specific selection, thereby affecting the dynamics of evolutionary processes mediated by maternal effects.性连锁（sex-linkage）的演化被预测会响应于性别特异性选择或性拮抗选择而发生。与该预测相符的是，绝大多数性连锁基因均与对应性别的生殖功能相关。除了直接参与生育力与繁殖力的性状外，母源效应（maternal effects）的介导因子也可能易于演化出性连锁特征，因为它们通过影响后代表型间接作用于雌性适合度。本研究针对卵生动物（oviparous species）中一类关键的产前母源效应介导因子——母体来源睾酮（testosterone）向卵内的转运——开展了性连锁遗传的检验。研究结果与母系遗传的预期一致：在日本鹌鹑（Coturnix japonica）中，其孙女的卵黄睾酮沉积水平与其外祖母（而非祖母）相似。该相似性并非源于产前发育阶段睾酮暴露所产生的非遗传预激效应，因为对卵黄睾酮水平的实验操控并未影响雌性个体后续向自身卵内转运睾酮的能力。取而代之的是，W染色体（W chromosome）和/或线粒体变异（mitochondrial variation）可能是本次观测到的母系遗传（matrilineal inheritance）模式的遗传基础。归根结底，母源效应介导因子沿母系的遗传方式，将使种群能够快速且直接地响应雌性特异性选择，进而改变由母源效应介导的进化过程的动态。