Department of Biology, University of North Carolina, Chapel Hill, North Carolina.
J Evol Biol. 2019 Jul;32(7):706-716. doi: 10.1111/jeb.13475. Epub 2019 Apr 29.
Relatively little is known about whether and how nongenetic inheritance interacts with selection to impact the evolution of phenotypic plasticity. Here, we empirically evaluated how stabilizing selection and a common form of nongenetic inheritance-maternal environmental effects-jointly influence the evolution of phenotypic plasticity in natural populations of spadefoot toads. We compared populations that previous fieldwork has shown to have evolved conspicuous plasticity in resource-use phenotypes ("resource polyphenism") with those that, owing to stabilizing selection favouring a narrower range of such phenotypes, appear to have lost this plasticity. We show that: (a) this apparent loss of plasticity in nature reflects a condition-dependent maternal effect and not a genetic loss of plasticity, that is "genetic assimilation," and (b) this plasticity is not costly. By shielding noncostly plasticity from selection, nongenetic inheritance generally, and maternal effects specifically, can preclude genetic assimilation from occurring and consequently impede adaptive (genetic) evolution.
关于非遗传继承是否以及如何与选择相互作用，从而影响表型可塑性的进化，人们知之甚少。在这里，我们通过实证评估了稳定选择和一种常见的非遗传继承形式——母体环境效应——如何共同影响蟾蜍自然种群中表型可塑性的进化。我们比较了先前的实地工作表明在资源利用表型中表现出明显可塑性的种群（“资源多态性”）与那些由于稳定选择有利于更窄范围的此类表型而似乎失去这种可塑性的种群。我们表明：(a) 这种在自然界中明显丧失可塑性的现象反映了一种条件依赖性的母体效应，而不是遗传可塑性的丧失，即“遗传同化”；(b) 这种可塑性没有代价。通过使非代价性可塑性免受选择的影响，非遗传继承一般，以及母体效应具体，可以防止遗传同化的发生，从而阻碍适应性（遗传）进化。
