The effect of social isolation on offspring performance: an evolutionary, ecological and molecular perspective

家庭生活在分类学上是一种广泛存在的现象，它需要家庭成员之间多方面的相互作用。特别是，在家庭生活的进化过程中，父母-后代和兄弟姐妹的互动被假设为相互影响，导致不同类型的互动（合作，中立或竞争）和角色。然而，由于过去对动物系统的关注，其中家庭生活是高度衍生和义务的，我们仍然缺乏关于各种社会互动及其在家庭群体进化中的相互作用的信息。为了解决这一知识差距，我们建议利用一个有趣的模型系统，埋葬甲虫系统，在这个系统中，近亲物种在依赖亲代照顾方面存在巨大差异。因此，将后代与家庭成员隔离将成为了解社会互动类型、程度和相互作用的核心工具。通过分析后代与父母和兄弟姐妹社会隔离的综合和分离效应，我们将研究在父母不在场的情况下，兄弟姐妹互动的类型和程度是否不同，以及当后代更多或更少依赖父母照顾时，兄弟姐妹互动的特征是否会发生变化。由于假设兄弟姐妹合作的进化是为了弥补照顾的减少，我们将专门测试那些不太依赖父母存在的物种是否更多地依赖兄弟姐妹的存在。此外，我们将分析恶劣的环境条件（高温和低温、低食物供应、高微生物负荷）如何影响对社会隔离的反应，以及父母-后代和兄弟姐妹合作是否可以缓冲低环境质量。在项目的最后一部分，我们将研究亲子和兄弟姐妹互动的遗传基础。具体来说，我们将比较与兄弟姐妹和/或父母分离的后代的基因表达模式，并检查三种物种的基因表达对短期亲代分离的反应，这三种物种的后代对亲代照顾的依赖程度有很大差异。拟议项目的结果不仅将阐明家庭相互作用的复杂性及其在家庭生活演变过程中不断变化的角色，而且还将增强我们对社会隔离对后代表现影响的一般理解。

Family life is a taxonomically widespread phenomenon that entails multifaceted interactions among family members. Especially, parent-offspring and sibling interactions have been hypothesised to affect each other leading to different types (cooperative, neutral or competitive) and roles of interactions during the evolution of family life. However, due to a past focus on animal systems, in which family living is highly derived and obligate, we still lack information about the role of the various social interactions and their interplay in the evolution of family groups. To address this gap of knowledge, we propose to take advantage of an intriguing model system, the burying beetle system, in which closely related species differ immensely in their reliance on parental care. Isolating offspring from family members will thereby serve as a central tool to obtain insights into the type, degree and interplay of social interactions. By analysing the combined and separated effect of social isolation of offspring from parents and siblings, we will examine whether the type and degree of sibling interactions is different in the absence than in the presence of parents and whether characteristics of sibling interactions changes when offspring become more or less dependent on parental care. Since it has been hypothesised that sibling cooperation evolved to compensate for a decreased benefit of care, we will specifically test whether species which rely less on the presence of parents, rely more on the presence of siblings. Furthermore, we will analyze how harsh environmental conditions (high and low temperature, low food availability, high microbial load) affect responses to social isolation and whether both parent-offspring as well as sibling cooperation can buffer against low environmental quality. In the final part of the project, we will study the genetic underpinnings of parent-offspring and sibling interactions. Specifically, we will compare gene expression patterns of offspring that had been isolated from siblings and/or parents and examine gene expression responses to short term parental separation among three species that differ substantially in the degree of offspring dependency on parental care. The result of the proposed project will not only shed light onto the intricacies of family interactions and their changing roles during the evolution of family life but will also enhance our general understanding of the consequences of social isolation on offspring performance.