Sibling cooperation in earwig families provides insights into the early evolution of social life

The evolutionary transition from solitary to social life is driven by direct and indirect fitness benefits of social interactions. Understanding the conditions promoting the early evolution of social life therefore requires identification of these benefits in nonderived social systems, such as animal families where offspring are mobile and able to disperse and will survive independently. Family life is well known to provide benefits to offspring through parental care, but research on sibling interactions generally focused on fitness costs to offspring due to competitive behaviors. Here we show experimentally that sibling interactions also reflect cooperative behaviors in the form of food sharing in nonderived families of the European earwig, Forficula auricularia. Food ingested by individual offspring was transferred to their siblings through mouth-to-anus contacts and active allo-coprophagy. These transfers occurred in both the presence and the absence of the tending mothers, even thou...

从独居到社群生活的演化过渡，由社会互动带来的直接与间接适合度收益所驱动。因此，要厘清促进社群生活早期演化的条件，需在非衍生社会系统中识别这类收益——例如后代具备移动能力、可扩散并能独立存活的动物家庭类社会体系。众所周知，家庭生活可通过亲代抚育为后代提供收益，但既往针对同胞互动的研究，多聚焦于竞争行为给后代带来的适合度成本。本研究通过实验证实，在欧洲球螋（Forficula auricularia）的非衍生家庭中，同胞互动亦体现出以食物共享为形式的合作行为。单个后代摄入的食物，可通过口-肛接触与主动的异体食粪行为（allo-coprophagy）传递给其同胞兄弟姐妹。这类食物传递在抚育母虫存在与否的情况下均会发生，即便……