About time: synchrony in onset of parental care influences cooperation and offspring performance in a burying beetle

In providing biparental care, each parent must coordinate its relative contribution to care with that of its partner. Previous studies have shown that each parent adjusts its contribution to care based on its partner's contribution and state. Here, the effect of timing caused by synchrony in the onset of parental care was investigated. Synchrony likely matters if the parent arriving earlier contributes more towards prehatching care, thereby altering the parents' relative contribution to posthatching care if the parent arriving later compensates for their partner's greater contribution to prehatching care. To test this idea, synchrony in the onset of care in the burying beetle Nicrophorus vespilloides was manipulated using a two-by-two factorial design with the following treatments: Both parents arrived synchronously at a fresh carcass; the parents arrived asynchronously such that the female arrived at a fresh carcass and the male arrived 24 h later; the parents arrived asynchronously such that the male arrived at a fresh carcass and the female arrived 24 h later, or both parents arrived synchronously at a 24-h-old carcass. We found that males provided more indirect care when the parents arrived asynchronously at the carcass compared with when they arrived synchronously. Despite this, larval survival to dispersal was lower in broods cared for by parents that arrived asynchronously potentially as a result of a reduction in the efficiency or quality of care being provided. Results indicate that asynchrony in the onset of parental care alters the parents' relative contribution to posthatching care possibly by disrupting synchrony in the reproductive physiology of the female and male. Thus, linking synchrony in reproductive behaviour with synchrony in reproductive physiology is encouraged in future work. • Male burying beetles provided more parental care when care began asynchronously. • Females cared equally regardless of synchrony in the onset of parental care. • Offspring performance was lower when parental care began asynchronously.