scholarly journals Allometry of evaporative water loss in marsupials: implications of the effect of ambient relative humidity on the physiology of brushtail possums (Trichosurus vulpecula)

2008 ◽  
Vol 211 (17) ◽  
pp. 2759-2766 ◽  
Author(s):  
C. E. Cooper ◽  
P. C. Withers
Keyword(s):  
Relative Humidity ◽  
Water Loss ◽  
Evaporative Water Loss ◽  
Trichosurus Vulpecula ◽  
Evaporative Water ◽  
Ambient Relative Humidity

scholarly journals Physiological regulation of evaporative water loss in endotherms: is the little red kaluta ( Dasykaluta rosamondae ) an exception or the rule?

2014 ◽  
Vol 281 (1784) ◽  
pp. 20140149 ◽  
Author(s):  
Philip C. Withers ◽  
Christine E. Cooper
Keyword(s):  
Water Loss ◽  
Thermal Conductance ◽  
Vapour Pressure Deficit ◽  
Evaporative Water Loss ◽  
Water Vapour Pressure ◽  
Published Data ◽  
Evaporative Heat Loss ◽  
Evaporative Water ◽  
Physiological Regulation ◽  
Ambient Relative Humidity

It is a central paradigm of comparative physiology that the effect of humidity on evaporative water loss (EWL) is determined for most mammals and birds, in and below thermoneutrality, essentially by physics and is not under physiological regulation. Fick's law predicts that EWL should be inversely proportional to ambient relative humidity (RH) and linearly proportional to the water vapour pressure deficit (Δwvp) between animal and air. However, we show here for a small dasyurid marsupial, the little kaluta ( Dasykaluta rosamondae ), that EWL is essentially independent of RH (and Δwvp) at low RH (as are metabolic rate and thermal conductance). These results suggest regulation of a constant EWL independent of RH, a hitherto unappreciated capacity of endothermic vertebrates. Independence of EWL from RH conserves water and heat at low RH, and avoids physiological adjustments to changes in evaporative heat loss such as thermoregulation. Re-evaluation of previously published data for mammals and birds suggests that a lesser dependence of EWL on RH is observed more commonly than previously thought, suggesting that physiological independence of EWL of RH is not just an unusual capacity of a few species, such as the little kaluta, but a more general capability of many mammals and birds.

Water turnover and the northern range of the koala (Phascolarctos cinereus).

2007 ◽  
Vol 29 (1) ◽  
pp. 85 ◽  
Author(s):  
I.D. Clifton ◽  
W.A.H. Ellis ◽  
A. Melzer ◽  
G. Tucker
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Water Loss ◽  
Evaporative Water Loss ◽  
Water Requirements ◽  
Water Turnover ◽  
Evaporative Water ◽  
Phascolarctos Cinereus ◽  
Energy Demands ◽  
Cooling Mechanism

Water turnover for koalas is positively correlated with the moisture content of selected trees suggesting that browse choice was driven by water requirements in summer but energy demands in winter. We compared the distribution of the koala to relative humidity and found that the bioregional delineation of the koala?s range corresponds closely to regions experiencing an average 9am relative humidity of less than 80% in February. This indicates that the northern coastal distribution of the koala may be limited by respiratory evaporative water loss as a cooling mechanism.

scholarly journals Thermoregulatory role of insensible evaporative water loss constancy in a heterothermic marsupial

2017 ◽  
Vol 13 (11) ◽  
pp. 20170537 ◽  
Author(s):  
Christine Elizabeth Cooper ◽  
Philip Carew Withers
Keyword(s):  
Relative Humidity ◽  
Water Loss ◽  
Physiological Role ◽  
Vapour Pressure Deficit ◽  
Evaporative Water Loss ◽  
Regulatory Control ◽  
Water Vapour Pressure ◽  
Evaporative Water ◽  
Ambient Temperatures

‘Insensible’ evaporative water loss of mammals has been traditionally viewed as a passive process, but recent studies suggest that insensible water loss is under regulatory control, although the physiological role of this control is unclear. We test the hypothesis that regulation of insensible water loss has a thermoregulatory function by quantifying for the first time evaporative water loss control, along with metabolic rate and body temperature, of a heterothermic mammal during normothermia and torpor. Evaporative water loss was independent of ambient relative humidity at ambient temperatures of 20 and 30°C, but not at 25°C or during torpor at 20°C. Evaporative water loss per water vapour pressure deficit had a positive linear relationship with relative humidity at ambient temperatures of 20 and 30°C, but not at 25°C or during torpor at 20 or 25°C. These findings suggest that insensible water loss deviates from a physical model only during thermoregulation, providing support for the hypothesis that regulation of insensible evaporative water loss has a thermoregulatory role.

Shell Resistance and Evaporative Water Loss from Bird Eggs: Effects of Wind Speed and Egg Size

1981 ◽  
Vol 54 (2) ◽  
pp. 195-202 ◽  
Author(s):  
James R. Spotila ◽  
Christina J. Weinheimer ◽  
Charles V. Paganelli
Keyword(s):  
Wind Speed ◽  
Water Loss ◽  
Egg Size ◽  
Evaporative Water Loss ◽  
Evaporative Water ◽  
Bird Eggs

Scaling of Evaporative Water Loss in Marsupials

1986 ◽  
Vol 59 (1) ◽  
pp. 1-9 ◽  
Author(s):  
David S. Hinds ◽  
Richard E. MacMillen
Keyword(s):  
Water Loss ◽  
Evaporative Water Loss ◽  
Evaporative Water
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