Tracing dietary protein in red-backed voles (Clethrionomys gapperi) using stable isotopes of nitrogen and carbon

Abstract

We examined the stable isotopes of nitrogen and carbon in a small mammal, the red-backed vole (Clethroinomys gapperi (Vigors, 1830)), to determine if isotope signatures reflect diet composition. Nitrogen- and carbon-isotope ratios in tissues from voles maintained on different protein levels in the laboratory were compared with wild-trapped voles. The isotopic fractionation of dietary nitrogen and carbon was also examined as food was digested in the stomach, incorporated into bone collagen, bioapatite, and hair, and excreted as feces. Nitrogen and carbon isotopes were fractionated differently depending on the isotopic composition and protein content of the diet. δ15N and δ13C values appear to be influenced by factors in addition to diet, such as macronutrients metabolized for respiration, metabolic rate, and periods of protein shortage.

Stable nitrogen and carbon isotope discrimination between juveniles and adults in an income-breeding small mammal (Peromyscus maniculatus)

“…These factors include differential assimilation by different tissues (Tieszen et al 1983;Sare et al 2005a), differences in tissue turnover rates (Hobson and Clark 1992;Miller et al 2008), nutritional stress (Hobson et al 1993;Kempster et al 2007;McCue and Pollock 2008), water stress (Schwarcz et al 1999), metabolic rates (MacAvoy et al 2006;Smith et al 2010), isotopic routing (Ambrose and Norr 1993;Martinez del Rio and Wolf 2005), and the ratios and amounts of carbon and nitrogen in the diet (Adams and Sterner 2000).…”

Stable carbon isotopes accurately predict diet selection by sheep fed mixtures of C3 annual pastures and saltbush or C4 perennial grasses

“…A range of animal tissues or by-products can be used for the prediction of diet using the technique (see review by Dalerum and Angerbjörn 2005). Examples include faeces (Sponheimer et al, 2003;De Smet et al, 2004), hair (Sponheimer et al, 2003;West et al, 2004), fat from plasma, liver, muscle or kidney (De Smet et al, 2004), whole blood (Kurle, 2002), stomach contents (Sare et al, 2005), milk (Camin et al, 2004), feathers (Hobson and Bairlein, 2003) and expired CO 2 (Passey et al, 2005).…”

Landscape bioarchaeology at Pacatnamu, Peru: inferring mobility from δ13C and δ15N values of hair

“…The similarity of bone and hair d 15 N values (Tables 1 and 2) from the same individuals provides a further basis for assuming preservation of original isotopic compositions in these samples. Because this population had easy access to marine resources and was, therefore, protein sufficient, there is no reason to suspect that normal tissue-diet differences in isotopic composition would be affected for either carbon (Ambrose and Norr, 1993) or nitrogen (Sare et al, 2005). The average offset between d 13 C of bone collagen and hair in this study is 1.5& (Table 2).…”

“…Sare et al (2005) have shown experimentally in small mammals that the hair-diet difference in carbon isotopic composition increases with decreasing protein consumption (Sare et al, 2005). However, low levels of dietary protein should not affect the hair-diet difference in this population.…”

“…Consequently, isotopic analysis of hair has been used to investigate aspects of diet that would be masked by long-term remodelling and protein mixing -e.g., seasonality (White, 1993), environmental relocations (Aufderheide et al, 1994), season of death (White, 1993), and subsistence strategies relating to food storage (Schwarcz and White, 2004). Because it is a tissue that can be accessed without injury to the individual, it has also been used for monitoring dietary change in extant animals and in controlled experiments (e.g., in reconstructing habitat use in animals [Schoeninger et al, 1998]), and mechanisms of protein metabolism in animals and humans (O'Connell and Hedges, 1999;Sare et al, 2005).…”