Tschirren Barbara, Ziegler Ann-Kathrin, Pick Joel L, Okuliarová Monika, Zeman Michal, Giraudeau Mathieu
Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
Proc Biol Sci. 2016 Sep 14;283(1838). doi: 10.1098/rspb.2016.1676.
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.
性连锁预计会因性别特异性或性拮抗选择而进化。与这一预测相符的是，大多数性连锁基因都与相应性别的繁殖相关。除了直接参与生育力和繁殖力的性状外，母体效应的介导因子可能易于进化为性连锁，因为它们通过对后代表型的影响间接影响雌性的适应性。在这里，我们测试了卵生动物产前母体效应的一个关键介导因子——母体来源的睾酮向卵中的转移——的性连锁遗传。与母系遗传一致，我们发现，在日本鹌鹑（Coturnix japonica）中，孙女在卵黄睾酮沉积方面与其外祖母（而非其祖父）相似。这种相似模式并非由于产前发育期间睾酮暴露的非遗传启动效应，因为对卵黄睾酮水平的实验操作并未影响雌性在其生命后期向自己的卵中转移睾酮。相反，W染色体和/或线粒体变异可能是观察到的母系遗传模式的基础。最终，母体效应介导因子沿母系的遗传将允许对雌性特异性选择做出快速而直接的反应，从而影响由母体效应介导的进化过程的动态。
