Diversification of family life: species and sex differences in parental behavior along a gradient of offspring dependency

家庭生活的进化导致了一种新的社会环境的出现：父母和子女相互见面和互动。作为这种相互作用的结果，父母的特征被期望适应后代提供的社会环境，而后代被期望适应父母所限定的社会环境。理论预测，这种共同进化的反馈循环会导致后代对亲代抚育的依赖程度增加，并促进亲代抚育行为的多样化。然而，由于我们缺乏合适的系统，我们可以找到后代对照顾的依赖程度不同的相关物种，因此我们对父母和后代在出现后以及在家庭生活巩固期间的行为多样化知之甚少。在这里，我们建议利用一个方便的模型系统-埋葬甲虫（Nicrophorus）系统，我们最近发现，在该系统中，近亲物种在后代对照料的依赖程度上表现出惊人的差异。该项目的目的是进行一项比较行为研究，以确定亲代和后代在亲缘关系密切的物种之间的行为差异，以及这些差异是否与依赖程度有关。例如，依赖性更强的物种的父母是否对后代数量的变化更敏感？我们将明确考虑父亲和母亲的行为，以测试共同进化反馈回路是否同时针对父亲和母亲的特征，以及这如何影响父母投资的性冲突。由于父母的抚育行为经常被证明是由激素调节的，我们还将比较家庭生活中的幼年激素滴度动态。该研究的结果数据将为亲代照顾和后代行为的进化和多样化提供新的和基本的见解。

The evolution of family life leads to the emergence of a novel social environment: parents and offspring meet and interact with each other. As a consequence of such interactions, parental traits are expected to adapt to the social environment provided by their offspring and offspring are expected to adapt to the social environment circumscribed by their parents. Theory predicts that such co-evolutionary feedback loops can result in an increasing degree of offspring dependency on parental care and also promote the diversification of parental care behaviour. However, as we lack suitable systems in which we can find related species with different degrees of offspring dependency on care, little is known about how parent and offspring behavior diversifies after emergence and during consolidation of family life. Here, we propose to take advantage of a convenient model system – the burying beetle (Nicrophorus) system, in which we recently discovered that closely related species show a striking variation in their magnitude of offspring dependence on care. The aim of the project is to conduct a comparative behavioral study to determine how parental and offspring behavior differs between closely related species and whether these differences are linked to the degree of dependency. For example, are parents of more dependent species more responsive to changes in brood size? We will explicitly consider both paternal and maternal behavior to test whether the co-evolutionary feedback loops target both, paternal and maternal traits and how this affects sexual conflict over parental investment. Since parental care behavior has often been shown to be regulated by hormones, we will also compare juvenile hormone titer dynamics during family life. The resulting data of the study will provide new and fundamental insights into the evolution and diversification of parental care and offspring behavior.