A Review of the Physiological Mechanisms in Stenocara gracilipes, Callipepla gambelii, Dipodomys merriami, and Dipsosaurus dorsalis Permitting Survival During Water Deprivation and Salt Imbalance in the Desert Environment.

Abstract

Water availability is limited in a desert ecosystem and many organisms have adapted unique mechanisms to maintain salt and water balance during periods of dehydration and rehydration. The darkling beetle (Stenocara gracilipes) and the Gambel’s quail (Callipepla gambelii) both employ metabolic changes, where the darkling beetle will oxidize fat to produce metabolic water¹. The Gambel’s quail has a field metabolic rate 60% lower than expected for a bird with similar mass and they also regulate their globular filtration rate to limit water loss through urine^{3, 4}. The kangaroo rat (Dipodomys merriami) and the desert iguana (Dipsosaurus dorsalis) both rely on food as their main water intake and the kangaroo rat has very efficient kidneys to retain water and excrete excess salts, while also having a lower water economy index than other mammals of similar size, indicating that they use water more efficiently^{7, 8}. The desert iguana will primarily excrete excess potassium obtained from their diet through their nasal fluids to maintain ion balance during a rehydration period⁹. This review showed that a variety of mechanisms have evolved in desert organisms to maintain salt and water balance during drought and rehydration.