Two lines of evidence for physiological control of insensible evaporative water loss by a tiny marsupial.

Christine Elizabeth Cooper, Philip Carew Withers

The Journal of experimental biology 2020 Dec 04

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We present two independent lines of evidence that a tiny dasyurid marsupial, the ningaui (Ningaui spp.), has acute physiological control of its insensible evaporative water loss below and within thermoneutrality. Perturbation of the driving force for evaporation by varying relative humidity, and therefore the water vapour pressure deficit between the animal and the ambient air, does not have the expected physical effect on evaporative water loss. Exposure to a helox atmosphere also does not have the expected physical effect of increasing evaporative water loss for live ningauis (despite it having the expected effect of increasing heat loss for live ningauis), but increases evaporative water loss for dead ningauis. We discuss the relative advantages and disadvantages of both experimental approaches for demonstrating physiological control of insensible evaporative water loss. An appreciation of physiological control is important because insensible evaporative water loss contributes to both water and heat balance, is clearly under environmental selection pressure, and potentially impacts the distribution of endotherms and their response to environmental change. © 2020. Published by The Company of Biologists Ltd.

Citation

Christine Elizabeth Cooper, Philip Carew Withers. Two lines of evidence for physiological control of insensible evaporative water loss by a tiny marsupial. The Journal of experimental biology. 2020 Dec 04;223(Pt 23)