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

家庭生活的演变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，父母的特征预计将适应其后代提供的社会环境，后代预计将适应由父母限制的社会环境。理论预测，这种共同进化的反馈回路可以导致后代对父母照顾的依赖程度增加，并促进父母照顾行为的多样化。然而，由于我们缺乏合适的系统，我们可以找到相关的物种与不同程度的后代依赖照顾，很少有人知道父母和后代的行为多样化后出现，并在巩固家庭生活。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，密切相关的物种表现出显着的变化，在他们的后代依赖照顾的幅度。该项目的目的是进行一项比较行为研究，以确定密切相关的物种之间的父母和后代行为如何不同，以及这些差异是否与依赖程度有关。例如，更依赖物种的父母对育雏大小的变化更敏感吗？我们将明确考虑父亲和母亲的行为，以测试共同进化的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。由于父母的照顾行为往往被证明是由激素调节，我们也将比较在家庭生活中的保幼激素滴度动态。这项研究的结果数据将为父母照顾和后代行为的演变和多样化提供新的基本见解。

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.