Summary
Changes in body condition ofUromastix acanthinurus are closely related to climatic factors and influenced by habitat vegetation.
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1.
The body mass index decreases significantly during the dry season and the contents of the digestive tract are responsible for most of these variations.
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2.
U. acanthinurus achieves a large total body water volume (75.4% adjusted body mass) by accumulating extracellular fluid (33% body mass) and maintains a normal level of hydration during the dry season. Total body water decreases during this period (due essentially to diminution of extracellular fluid) but blood volume and plasma volume are almost unaffected.
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3.
During spring there is an increase in body solids, essentially as fat reserves.
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4.
The electrolyte balance also exhibits seasonal variations. Plasma sodium concentration increases significantly during the dry period, in relation to the decrease of extracellular fluid. Return to normal values after rainfall results from intake of a diet low in sodium. Plasma potassium shows only random variation and appears to be regulated by excretion via the nasal salt gland and in cloacal pellets.
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5.
Under field conditions, changes in the internal environment appear more pronounced in the Saharan Agamid,Uromastix acanthinurus than in its analog, the North American Iguanid,Sauromalus obesus.
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Lemire, M., Grenot, C. & Vernet, R. Water and electrolyte balance of free-living Saharan lizards,Uromastix acanthinurus (Agamidae). J Comp Physiol B 146, 81–93 (1982). https://doi.org/10.1007/BF00688720
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DOI: https://doi.org/10.1007/BF00688720