Does acclimation to contrasting atmospheric humidities affect evaporative water loss in the South American subterranean rodentCtenomys talarum?

Abstract

Water conservation is challenging for terrestrial life since water is continuously lost through respiration, excretion, and cutaneous evaporation. Total evaporative water loss (TEWL) is an important component of the water budget. In general, TEWL is mainly determined by biophysical mechanisms, such as ambient temperature (T a) and humidity. However, it has also been suggested that TEWL can be actively regulated in the short term to confront environmental conditions and be further modified by development and acclimation. Thus, regulation of TEWL might be complex, especially in semifossorial species, which continuously meet contrasting conditions at the surface. We evaluated the influence of acclimation to different ambient humidities on TEWL and associated metabolic parameters in the subterranean rodent Ctenomys talarum. We found that changing humidity acclimation conditions may not elicit modifications on TEWL. Both the water vapor-saturated burrows and the stability in TEWL at different humidities would lead to overheating problems at high ambient temperatures. Then, other forms of heat loss such as dry conductance may be enhanced. Fossoriality apparently evolved as a way of surviving increasing aridity conditions; therefore, other behavioral adjustments might be employed to counteract the high humidity within burrows.

Antioxidant response to severe hypoxia in Brandt's vole Lasiopodomys brandtii

“…Other subterranean rodents only spend a certain amount of time underground (Schleich & Antenucci 2009; Baldo et al . 2016; Šumbera et al . 2020), unlike the Spalax species; however, these animals may experience more drastic O 2 fluctuations (frequent switches between normoxia and hypoxia).…”

“…It has been reported that Spalax ehrenbergi can survive 3% O 2 for 8 h without significant deleterious effects, while similar-sized rats were found to die after 2-4 h (Avivi et al 1999). Other subterranean rodents only spend a certain amount of time underground (Schleich & Antenucci 2009;Baldo et al 2016;Šumbera et al 2020), unlike the Spalax species; however, these animals may experi-ence more drastic O 2 fluctuations (frequent switches between normoxia and hypoxia). Studies on subterranean rodents have generally been limited to the adaptive mechanisms in blind mole rats and naked mole rats because of their unique life history and spectacular hypoxia tolerance (Malik et al 2012;Peterson et al 2012;Grimes et al 2014;Schmidt et al 2017).…”