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性特异性选择或性拮抗选择而发生。与该预测相符，绝大多数性连锁基因在对应性别中与生殖功能存在关联。除了直接参与生育力与繁殖力的性状外，母性效应（maternal effects）介导因子也更易演化出性连锁特征，因其可通过影响后代表型，间接作用于雌性适合度。本研究针对卵生动物（oviparous species）中产前母性效应的关键介导因子——母源睾酮（testosterone）向卵内的传递过程——检测其性连锁遗传模式。与母系遗传（maternal inheritance）的预期一致，我们在日本鹌鹑（Coturnix japonica）中发现，雌性孙辈仅与外祖母在卵黄睾酮沉积水平上表现出相似性，而非与祖母。该相似性模式并非源于产前发育阶段睾酮暴露所引发的非遗传预编程效应，因为对卵黄睾酮水平进行实验操控后，并未影响雌性个体后续向自身卵内传递睾酮的能力。进一步分析显示，W染色体与/或线粒体的变异可能是所观测到的母系遗传模式的成因。最终，母系传递的母性效应介导因子的遗传模式，将使种群能够快速且直接地响应雌性特异性选择，进而改变由母性效应介导的演化过程的动态。