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.

在双亲抚育的物种中，存在性冲突：双亲均受选择压力驱动，通过尽可能将繁殖工作量转移给另一方，以减少自身的抚育投入。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协商等策略。然而，由于雌性负责产生卵子，这或许赋予雌性通过母体效应（maternal effects）调控雄性行为的能力，进而改变后代表型。为验证该假说，我们以埋葬甲（Nicrophorus vespilloides）为研究对象，操控产前环境（即雄性是否存在），开展交叉抚育实验，并追踪产前环境对后代及双亲抚育表现的后续影响。研究发现，当雌性在雄性存在的环境中产卵时，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，会减少对卵子的投入。此外，在雄性存在环境中产下的育幼群，在双亲抚育期间体重增长更多，且这一增长是以雄性自身的体重损失为代价。与我们的预期相反，雄性对在其存在环境中产下的育幼群的照料投入更少。本研究结果提供了实验证据，表明雌性可通过根据产前环境调整母体效应，在繁殖过程中调控雄性行为。但雌性并未提升雄性的抚育投入，反而抑制了雄性的食物摄取，从而为育幼群留存了更多食物。