WOLF, B.O.: Using stable isotopes approaches to explore animal physiological ecology

Stable isotope methods have been used in a number of situations to study resource use by animals and rely on the observation that the isotopic composition of an animal’s tissues reflects that of its diet. The stable isotope approach can also tell us about an animal’s physiological status. For example, in some cases carbon isotope analysis of consumer tissues can indicate the macro-nutrients being utilized and potentially where these nutrients are being routed to in the consumer’s body. Nitrogen isotope analyses of consumer tissues can provide additional information about the nutritional status and trophic interactions of animal consumers. Carbon isotope analyses of breath carbon dioxide can even provide information about macro-nutrient catabolism in almost real time. Finally, the analyses of hydrogen isotope composition of the body water pool of free-living animals may provide information on thermal stress, evaporative water loss as a function of total water flux, and water resource use. Because of pervasiveness of fractionating processes in plants, animals and the environment, the stable isotope approach holds promise for examining the use and movement of specific macro-nutrients and the fate of water resources from a physiological perspective in free-living animals.