Are heat of flight and body mass related with zoonotic potential in bats?

Understanding the ecology, physiology, and interactions with humans of viral reservoirs such as bats – the mammalian order hosting the highest zoonotic viral richness– is key to forecast the emergence of new infectious diseases. The flight as fever hypothesis has been proposed to explain why bats host, without overt signs of illness, a high diversity of viruses that show high virulence in case of zoonotic spillover. High metabolic rates and the amount of heat produced during flight in bats would stimulate immune responses, thus allowing to control viral replication while promoting viral adaptation to febrile conditions and ultimately increasing viral richness. Here we use biophysical modelling to calculate the amount of heat produced during flight and examine if a relationship exists with observed viral richness across 75 bat species. As predicted by the flight as fever hypothesis, our phylogenetically-informed analyses detect a significant relationship between heat of flight and viral richness.