Evaporative water loss of subterranean rodents: a South America-Africa comparison

OKROUHLÍK J; LUNA F; MLADěNKOVÁ N; UMBERA R; ANTENUCCI CD

Perth

Congreso; 12th International Mammalogical Congress; 2017

Salt and water balance is essential for life but is challenging, especially for those organisms that require special water regulatory mechanisms because of their life in extreme habitats. In endotherms, a significant avenue of water loss is evaporation.Evaporative water loss (EWL) is inevitable, but individuals can limit such loss and use it for cooling, as metabolically-produced heat is dissipated by evaporating body water. One of the most important challenges for mammals living in an underground environment is the need to dig new burrows through a dense substrate in an almost water saturated atmosphere. The heat produced during digging in such an environment could cause overheating, especially at ambient temperatures (Ta) within and above the thermoneutral zone (TNZ). The aim of this study was to evaluate the effect of Ta on EWL and energy metabolism of subterranean species from different rodent families, African mole-rats (Bathyergidae), and South American coruros (Octodontidae) and tuco-tucos (Ctenomiydae). Individuals of all species follow a typical endotherm pattern, maintaining relatively stable EWL below and within TNZ and increasing evaporation above TNZ. However, they show difference in the total EWL,especially above TNZ. We relate ecological pattern to the underlying physiological mechanisms aiming to understand the evaporative water and heat loss in subterranean rodents. We analyzed both social and solitary species, so we focus, also, on the effect of sociality on EWL. Finally, by comparing different unrelated species of subterranean mammals, we gain insights into thefactors that influence the broad scale pattern of EWL in these mammals.