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UBC Theses and Dissertations

The effect of torpor on pulmo-cutaneous water loss in Perognathus parvus Guthrie, Donald Raymond


Studies were conducted to determine the effect of torpor on the pulmo-cutaneous water loss of a small, fossorial desert rodent, Perognathus parvus. Since the pulmonary and cutaneous components of the water budget are strongly affected by ambient temperature and humidity, these losses are extremely Important In determining the ability of an animal to maintain positive water balance. Simultaneous measurements of pulmo-cutaneous water loss and metabolic rate were made over a range of ambient temperatures of 10-35 C for both torpid and normothermlo animals. Additional experiments were conducted to determine the ratio of pulmonary to cutaneous water loss, and to determine the relationship of these losses to ambient temperature. Models of energy budgets and water budgets were constructed to assist in determining the effect of variable amounts of torpor over the range of ambient temperature of 0-30 C. It was found that normothermic animals could maintain positive water balance from 0-20 C at 0% relative humidity, but torpid animals were always in negative water balance under the same conditions. The inability of torpid animals to maintain positive water balance is attributed to the necessity of balancing the relatively fixed cutaneous loss against the much-reduced metabolic water production. It is concluded that torpor cannot serve as a water-conserving mechanism in this species at 0% relative humidity.

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