Does acclimation to contrasting atmospheric humidities affect evaporative water loss in the South American subterranean rodent Ctenomys 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.