Discrimination factors (Δ15N and Δ13C) in an omnivorous consumer: effect of diet isotopic ratio

作者：Stéphane Caut, Elena Angulo, Franck Courchamp · 发表于：Functional Ecology · 年份：2007 · DOI：10.1111/j.1365-2435.2007.01360.x · 被引用次数：187 · 研究领域：Isotope Analysis in Ecology、Marine animal studies overview、Pacific and Southeast Asian Studies

1 Naturally occurring stable isotopes in resources and their consumer allow the estimation of nutritional flows between the two and have been much used to improve our understanding of the nutritional ecology of free-living animals. 2 The difference in isotopic composition between an animal and its diet is represented by a discrimination factor. Carbon and nitrogen flows are estimated by calculating the discrimination factors in stable isotope ratios (δ15N and δ13C), which are presumed to be c. 3‰ and 1‰ heavier in the consumer tissues than those in their resources, respectively. 3 The discrimination factor is known to vary according to species, tissue, age, growth rates and food quality, but the estimation of discrimination factors is difficult and a fixed discrimination factor is usually used in diet reconstruction. It has also been suggested that discrimination factors could vary linearly with the diet isotopic ratio. If this linear relationship could be demonstrated using regression, this would provide an adequate method for the estimation of discrimination factors. In order to understand how diet isotopic ratios affect the discrimination factor, we investigated the pattern of its change in nitrogen (Δ15N) and carbon (Δ13C) in different tissues (liver, muscle and hair) of an omnivore species, the rat Rattus rattus. We fed captive rats with diets of the same nutritional quality but on different isotopic ratios. 4 First, discrimination factors for Δ15N and Δ13C showed great ...