Seasonal acclimation of energy and water balance in desert-dwelling rodents of South America

Abstract

Seasonal changes in environmental conditions may induce reversible physiological adjustments in organisms. We studied the acclimatization for multiple stressors in energy expenditure and water balance in Galea leucoblephara, a diurnal hystricognath rodent native to South America that experiences significant changes in temperature, precipitation, and food availability among seasons. We conducted a field study in the Monte Desert of Mendoza, Argentina, where we evaluated adult individuals' physiological status during two contrasting seasons in terms of climate and primary productivity. Reduced temperature, rainfall, and primary productivity during winter were associated with a decrease of 70% in basal metabolic rate (BMR), 30% in total evaporative water loss (TEWL), and 9% in body mass (M_b). In contrast, higher water availability, high temperature, and primary productivity during summer, induced significant increases in energy expenditure and evaporative water loss. As expected, the proportion of dietary items consumed by G. leucoblephara varied seasonally, resulting in a more diverse diet during summer. Our results illustrate how G. leucoblephara can cope with high seasonal contrasts in water availability, temperature, and food availability by modifying its physiological performance. Our data provide support for the hypothesis of physiological flexibility in energetic traits and water balance in response to the environmental challenges of the Monte Desert.