Rapidly increasing global temperatures are predicted to impact a myriad of biological and ecological processes, including reproductive behaviors related to fitness. As an example, the dung beetle Phanaeus vindex lay eggs inside of brood balls (provisioned out of dung) and buries brood balls underground for the entirety of offspring development. The depth of the brood ball can directly impact the temperatures young experience, with important consequences for beetle development. Brood balls buried deeper in the soil experience cooler, more consistent temperatures than brood balls closer to the surface, which experience warmer, more variable conditions. Because climate change is increasing both temperature mean and variation, we wanted to know if females will alter their breeding behavior in response to climate change by burying brood balls deeper in the ground. We placed fertilized females in small field enclosures and allowed them to reproduce and bury brood balls. Half of the enclosures were controls that tracked daily fluctuations, and half of the enclosures simulated climate change with increases in temperature mean and variation (5 ± 3.4°C above control treatments). We measured the number, mass, and burial depth of brood balls of females in control and warming treatments.
Results/Conclusions
We found that females altered their breeding behavior in response to increased temperature mean and variation. Females in warming treatments buried brood balls deeper (p=0.05) and produced smaller brood balls (p=0.04) than control females, while there was not difference in the number of brood balls produced. Our data suggest that females in warming treatments sought suitable developmental temperatures for young by burying brood balls deeper in the soil. However, burying brood balls deeper came at a cost, as the amount of dung provisioned to each offspring in the brood ball was significantly less in warming treatments than controls. Importantly, brood ball mass is indicative of offspring size at adulthood, a fitness proxy. Overall, our data suggest that females may be able to buffer young from detrimental temperatures stemming from climate change, to some extent, through behavioral modifications.