Thermal Variation Regulates the Trade-Off Between Pre- and Post-Hatching Investment in a Burying Beetle

Understanding how organisms respond to thermal stressors over short- and long-term timescales is essential for assessing and predicting their resilience and vulnerability to environmental changes and climate fluctuations. Here, using a biparental-care burying beetle (Nicrophorus vespilloides), we tested whether and how parental investment in carcass preparation and thermal condition interact to influence subsequent parental care behaviour and reproductive success. We employed a 3 × 2 factorial experiment, manipulating the levels of parental investment in carcass preparation (Reduced, Control, and Elevated) and ambient temperatures (benign: 20°C and harsh: 23°C) in breeding pairs. We found that (1) irrespective of ambient temperature, males in the Reduced group decreased their pre-hatching care. (2) Across all investment groups, both sexes under the higher temperature reduced post-hatching care. (3) Carcass-preparation investment and thermal condition interactively influenced reproductive success. Overall, the harsh temperature decreased reproductive success. Furthermore, beetle pairs experienced reduced carcass-preparation investment producing fewer eggs and lighter broods, while those experienced elevated carcass-preparation investment producing smaller and lighter broods. Our findings provide new insights into how thermal stress affects parental investment strategies, and enhance our understanding of the phenotypic plasticity in reproductive strategies that animals employ to cope with climate change.