Parental care has evolved multiple times in the animal kingdom and includes all parental traits that enhance offspring fitness. The evolution of care can lead to prolonged associations between parents and their offspring. This, in turn, can drive parent–offspring coevolution, creating systems in which multiple care behaviors are exhibited and potentially resulting in offspring becoming more dependent on parental care. Parental care often takes indirect forms, such as nest building, while direct care behaviors, like feeding, which involve physical interaction with offspring, are generally less frequent. However, in species where both types of care occur, the extent to which offspring rely on indirect versus direct care is often unknown. In this study, we investigated the roles and relative importance of direct and indirect care in a system where offspring are highly dependent on parental care. We conducted an experiment in which we manipulated the duration and composition of direct and indirect post-hatching care in the burying beetle Nicrophorus orbicollis. Burying beetles reproduce by exploiting small vertebrate carcasses, which they bury and convert into a nutritious nursery for their offspring. In addition to modifying the food resource, parents actively feed their offspring. We found that direct care had a greater effect on offspring growth and survival than indirect care, although indirect care also enhanced fitness. The greater reliance on feeding over indirect care is likely the result of sibling competition for food. Our study underscores the complexity and multi-layered nature of parental care strategies and their effects on offspring performance.
Prang et al. (Wed,) studied this question.