Data from: Flexible parents: joint effects of handicapping and brood size manipulation on female parental care in Nicrophorus vespilloides

Parental care is highly variable, reflecting that parents make flexible decisions in response to variation in the cost of care to themselves and the benefit to their offspring. Much of the evidence that parents respond to such variation derives from handicapping and brood size manipulations, the separate effects of which are well understood. However, little is known about their joint effects. Here we fill this gap by conducting a joint handicapping and brood size manipulation in the burying beetle Nicrophorus vespilloides. We handicapped half of the females by attaching a lead weight to their pronotum, leaving the remaining females as controls. We also manipulated brood size by providing each female with 5, 20 or 40 larvae. In contrast to what we predicted, handicapped females spent more time provisioning food than controls. We also found that handicapped females spent more time consuming carrion. Furthermore, handicapped females spent a similar amount of time consuming carrion regardless of brood size, while controls spent more time consuming carrion as brood increased. Females spent more time provisioning food towards larger broods, and females were more likely to engage in carrion consumption when caring for larger brood. We conclude that females respond to both handicapping and brood size manipulations, but these responses are largely independent of each other. Overall, our results suggest that handicapping might lead to a higher investment into current reproduction, and that it might be associated with compensatory responses that negate the detrimental impact of higher cost of care in handicapped parents.

亲代抚育（parental care）具有高度的变异性，这反映出双亲会根据自身抚育成本以及对后代的收益变化做出灵活决策。当前支持双亲会响应此类变化的大量证据，均来自负重操控（handicapping）与育雏规模操控（brood size manipulation）两类实验，且二者各自的效应已得到充分阐明。然而，学界对二者的联合效应却知之甚少。本研究以埋葬甲虫（Nicrophorus vespilloides）为研究对象，通过同时开展负重操控与育雏规模操控，填补了这一研究空白。我们为半数雌性个体的前胸背板附着铅块以实施负重处理，剩余雌性作为对照组；同时通过为每只雌性提供5、20或40只幼虫，完成育雏规模的操控。与我们的预测相悖的是，负重处理组雌性的食物投喂时长显著长于对照组。此外，负重处理组雌性的腐肉取食时长也更长。进一步分析显示，负重处理组雌性的腐肉取食时长不受育雏规模影响，而对照组雌性的腐肉取食时长则随育雏规模增大而增加。雌性个体对更大育雏群的食物投喂时长更长，且在抚育更大育雏群时更倾向于进行腐肉取食。我们据此得出结论：雌性甲虫会同时响应负重操控与育雏规模操控，但这两类响应在很大程度上相互独立。总体而言，本研究结果表明，负重处理可能会促使双亲提升当前繁殖投入，且可能伴随补偿性响应，以抵消负重处理组双亲因抚育成本升高带来的不利影响。