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

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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.