Physiological responses to fasting in bats

Abstract

The evolution of powered flight afforded bats the opportunity to fill ecological niches void of non-volant mammals, a circumstance that might explain their remarkable diversity in terms of number of species, diet, and habitat types that they occupy. However, besides its clear ecological advantages, the evolution of powered flight brought about high energetic costs for bats. To compensate for these costs, bats have evolved a variety of energy-saving thermoregulatory traits. The mechanisms underlying these attributes make bats a fascinating model for exploring physiological responses to fasting. In this chapter, we document the diversity of physiological traits behind the ability of bats to undergo long periods of fasting, and we associate it with their respective diets. At one extreme are hematophagous species that are unable to fast longer than 72 h due to its apparent inability to store and mobilize endogenous fuels; at the other are insectivorous vespertilionid and rhinolophid species that can fast for months at a stretch. Despite their ecological importance, far less is known about adaptations to fasting in bats than non-volant mammals or birds. Many questions remain open regarding the physiology, endocrinology, biochemistry, and energetics of fasting in bats and we hope that this review will encourage further investigation on this topic.