Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Crawley WA 6009, Australia.
Proc Biol Sci. 2020 Dec 9;287(1940):20202538. doi: 10.1098/rspb.2020.2538.
The capacity for parents to influence offspring phenotypes via nongenetic inheritance is currently a major area of focus in evolutionary biology. Intriguing recent evidence suggests that sexual interactions among males and females, both before and during mating, are important mediators of such effects. Sexual interactions typically extend beyond gamete release, involving both sperm and eggs, and their associated fluids. However, the potential for gamete-level interactions to induce nongenetic parental effects remains under-investigated. Here, we test for such effects using an emerging model system for studying gamete interactions, the external fertilizer . We employed a split-ejaculate design to test whether exposing sperm to egg-derived chemicals (ECs) from a female would affect fertilization rate and offspring viability when those sperm were used to fertilize a different female's eggs. We found separate, significant effects of ECs from non-fertilizing females on both fertilization rate and offspring viability. The offspring viability effect indicates that EC-driven interactions can have nongenetic implications for offspring fitness independent of the genotypes inherited by those offspring. These findings provide a rare test of indirect parental effects driven exclusively by gamete-level interactions, and to our knowledge the first evidence that such effects occur via the gametic fluids of females.
父母通过非遗传继承影响后代表型的能力是进化生物学的一个主要研究领域。最近引人关注的证据表明，雌雄两性在交配前和交配期间的性相互作用是这种影响的重要介导因素。性相互作用通常不仅仅涉及配子（精子和卵子）的释放，还包括它们相关的液体。然而，配子水平相互作用诱导非遗传亲本效应的潜力仍未得到充分研究。在这里，我们使用外部受精剂这一新兴的配子相互作用研究模型系统来检验这种效应。我们采用分裂精液设计来测试当这些精子用于受精另一个雌性的卵子时，雄性的精子暴露于雌性来源的卵子化学物质（ECs）是否会影响受精率和后代活力。我们发现非受精雌性的 ECs 对受精率和后代活力有单独的、显著的影响。后代活力的影响表明，EC 驱动的相互作用可能对后代的适应性产生非遗传影响，而与后代遗传的基因型无关。这些发现为纯粹由配子水平相互作用驱动的间接亲本效应提供了一个罕见的测试，并且据我们所知，这是首次证明这种效应通过雌性的配子液发生。
