Biparental care is more than the sum of its parts: experimental evidence for synergistic effects on offspring fitness

Despite an extensive body of theoretical and empirical literature on biparental cooperation, it is still unclear whether offspring fare equally, better, or worse when receiving care by two parents versus a single parent. Some models predict that parents should withhold the amount of care they provide due to sexual conflict, thereby shifting as much of the workload as possible to their partner. This conflict should lead to offspring faring worse with two parents. Yet, other models predict that when parents care for their offspring together, their individual contributions can have synergistic (more than additive) effects on offspring fitness. Under this scenario, biparental cooperation should lead to offspring faring better with two parents. We address this fundamental question using a unique experimental design where we compared offspring fitness when the two parents worked together (biparental treatment) and when the two parents worked separately (uniparental treatment), while keeping c...尽管关于双亲合作（biparental cooperation）的理论与实证研究文献已颇为丰富，但目前仍未明确：后代在获得双亲照料与单亲照料时，其生存状况究竟是相当、更优，还是更劣。部分模型预测，受性冲突（sexual conflict）影响，亲本将缩减自身提供的照料投入，尽可能将抚育负荷转移给配偶。此类冲突会导致后代在双亲照料下的生存状况更差。然而，另有模型提出，当双亲共同照料后代时，二者的个体贡献可对后代适合度（offspring fitness）产生协同效应（超出累加效应）。在此情境下，双亲合作应会使后代在双亲照料下的生存状况更优。本研究采用独特的实验设计探讨这一核心科学问题：我们比较了双亲共同抚育（biparental treatment）与双亲分别抚育的单亲处理组（uniparental treatment）下的后代适合度，同时保持……