Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Australia.
Biol Lett. 2021 Jul;17(7):20210213. doi: 10.1098/rsbl.2021.0213. Epub 2021 Jul 7.
There has been an explosion of recent evidence that environments experienced by fathers or their ejaculates can influence offspring phenotypes (paternal effects). However, little is known about whether such effects are adaptive, which would have far-reaching implications for the many species facing rapidly changing environments. For example, some arguments suggest paternal effects might be a source of cross-generational plasticity, preparing offspring to face similar conditions to their father (anticipatory hypothesis). Alternatively, ejaculate-mediated effects on offspring may be non-adaptive by-products of stress. Here, we conduct an experiment to distinguish between these predictions, exposing ejaculates of the externally fertilizing mussel to ambient (19°C) and high (24°C) temperatures, then rearing offspring groups in temperatures that match and mismatch those of sperm. We find that, overall, high temperature-treated sperm induced higher rates of normal offspring development and higher success in transitioning to second-stage larvae, which may represent adaptive epigenetic changes or selection on sperm haplotypes. However, the progeny of high temperature-treated sperm did not perform better than those of ambient temperature-treated sperm when rearing temperatures were high. Overall, these findings offer little support for the anticipatory hypothesis and suggest instead that beneficial paternal effects may be eroded when offspring develop under stressful conditions.
最近有大量证据表明，父亲或其精液经历的环境可以影响后代的表型（父系效应）。然而，人们对这些影响是否具有适应性知之甚少，这对许多面临快速环境变化的物种将产生深远的影响。例如，一些观点认为，父系效应可能是跨代可塑性的一个来源，使后代能够适应与其父亲相似的环境（预期假说）。或者，精液对后代的影响可能是非适应性应激的副产品。在这里，我们进行了一项实验，以区分这些预测，将外部受精贻贝的精液暴露在环境（19°C）和高温（24°C）下，然后在与精子温度相匹配和不匹配的温度下饲养后代群体。我们发现，总的来说，高温处理的精子诱导了更高比例的正常后代发育和更高比例的成功过渡到第二阶段幼虫，这可能代表了适应性的表观遗传变化或对精子单倍型的选择。然而，当饲养温度较高时，高温处理的精子的后代表现并不优于常温处理的精子的后代。总的来说，这些发现几乎没有支持预期假说的证据，反而表明，当后代在压力条件下发育时，有益的父系效应可能会被削弱。
