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University of Arizona (1977)

PHYSIOLOGICAL ECOLOGY OF THE SMALLEST DESERT MAMMAL, NOTIOSOREX CRAWFORDI

Lindstedt, Stan Lee

Titre : PHYSIOLOGICAL ECOLOGY OF THE SMALLEST DESERT MAMMAL, NOTIOSOREX CRAWFORDI

Auteur : Lindstedt, Stan Lee

Université de soutenance : University of Arizona

Grade : Doctor of Philosophy (PhD) 1977

Résumé
Small size and slight thermal insulation make shrews important animals for the study of thermoregulation. High metabolism and dependence on water would seem to make them poorly suited for desert survival. However, the desert shrew has solved the dilemma of energy balance and water economy to survive in the hot arid deserts of North America. The desert shrew was found to be relatively heattolerant compared to other shrews. Its standard metabolism, when corrected for weight, is the lowest measured in any shrew species (17.12 W*kg . Because its internal heat production is low it can tolerate greater environmental heat loads before it must expend water for cooling. At high ambient temperatures (37 C) the desert shrew loses half of its total metabolic heat production by the evaporation of water. Water for thermoregulation is available to these non-drinking insectivores because of scant urinary and respiratory water loses. The kidney morphology of the desert shrew suggests a urine concentrating ability far in excess of other shrews. This non-burrowing shrew further reduces its heat load behaviorally. It occupies some of the most thermally protected above-ground microhabitats that are available and it is active at night. Data for metabolism, evaporation, radiation and convection were combined to describe the climate space of the desert shrew. This smallest desert mammal has a relatively high tolerance of environmental heat loads which is reflected in the boundaries of its climate space.

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