Effects of ambient water vapor pressure and temperature on evaporative water loss inPeromyscus maniculatus andMus musculus

Abstract

The effects of ambient water vapor pressure (VP) and temperature on evaporative water loss (EWL) from the head and trunk ofPeromyscus maniculatus andMus musculus were measured with dew point hygrometry. At a given ambient temperature both head and trunk EWL were directly proportional to the water vapor pressure deficit. Cutaneous EWL in both species was directly related to the difference between saturated VP at skin temperature and ambient VP which is consistent with a simple diffusion process. In both species EWL from the head was independent of ambient temperature between 20 and 35 °C while the rate of cutaneous EWL more than doubled at 35 °C indicating a change in the water permeability of the skin. Possible mechanisms for this increase are discussed.