Data from: Females manipulate behavior of caring males via prenatal maternal effects

In species with biparental care, there is sexual conflict as each parent is under selection to minimize its personal effort by shifting as much as possible of the workload over to the other parent. Most theoretical and empirical work on the resolution of this conflict has focused on strategies used by both parents, such as negotiation. However, because females produce the eggs, this might afford females with an ability to manipulate male behavior via maternal effects that alter offspring phenotypes. To test this hypothesis, we manipulated the prenatal conditions (i.e., presence or absence of the male), performed a cross-fostering experiment, and monitored the subsequent effects of prenatal conditions on offspring and parental performance in the burying beetle Nicrophorus vespilloides. We found that offspring were smaller at hatching when females laid eggs in presence of a male, suggesting that females invest less in eggs when expecting male assistance. Furthermore, broods laid in the presence of a male gained more weight during parental care, and they did so at the expense of male weight gain. Contrary to our expectations, males cared less for broods laid in the presence of a male. Our results provide experimental evidence that females can alter male behavior during breeding by adjusting maternal effects according to prenatal conditions. However, rather than increasing the male’s parental effort, females appeared to suppress the male’s food consumption, thereby leaving more food for their brood.

在存在双亲育幼（biparental care）的物种中，存在性冲突：自然选择会促使双亲尽可能将抚育工作量转移给对方，以减少自身的投入成本。目前针对该冲突解决机制的多数理论与实证研究，均聚焦于双亲所采用的诸如协商之类的策略。然而，由于雌性负责产卵，这可能赋予雌性通过母体效应（maternal effects）改变后代表型（phenotypes）来操控雄性行为的能力。为验证这一假说，我们以埋葬甲（Nicrophorus vespilloides）为研究对象，操控其产前环境（即雄性是否在场），开展了交叉抚育实验，并监测了产前环境对后代及双亲抚育表现的后续影响。我们发现，当雌性在雄性在场的环境下产卵时，孵化后的后代体型更小，这表明雌性在预期能获得雄性协助时，会减少对卵的投入。此外，在雄性在场环境下产下的卵簇，在抚育期间的体重增长更多，而这一增长是以雄性自身的体重增长为代价的。与我们的预期相反，雄性对在雄性在场环境下产下的卵簇的抚育投入更少。我们的研究结果提供了实验证据，证明雌性可以通过根据产前环境调整母体效应，在繁殖过程中改变雄性的行为。但值得注意的是，雌性并未提升雄性的抚育投入，反而似乎抑制了雄性的食物摄取，从而为后代留下了更多食物。