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

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

Congreso; 12th International Mammalogical Congress; 2017

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