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Converting isotope ratios to diet composition - the use of mixing models - June 2010
Citation:
PHILLIPS, D. L. Converting isotope ratios to diet composition - the use of mixing models - June 2010. Presented at American Society of Mammalogists, Laramie, WY, June 11 - 15, 2010.
Impact/Purpose:
One application of stable isotope analysis is to reconstruct diet composition based on isotopic mass balance.
Description:
One application of stable isotope analysis is to reconstruct diet composition based on isotopic mass balance. The isotopic value of a consumer’s tissue reflects the isotopic values of its food sources proportional to their dietary contributions. Isotopic mixing models are used to estimate these dietary contributions. This presentation first outlines a basic mixing model and its assumptions. This model is then built upon to examine additional complicating factors: (a) sampling and measurement variability; (b) differences in elemental concentrations (e.g., C/N ratios) among different foods; and (c) increasing numbers of food sources. Mixing models incorporating each of these features are demonstrated with simple examples of mammal diets. Publicly available models (and where to get them) are mentioned, as are other complicating factors and possible future directions for model development.