Hydrogen and oxygen isotopes in vertebrate tissues vary by diet type

Linda M. Reynard ^1* Jennifer N. Leichliter ² Daniela E. Winkler ³ Marcus Clauss ⁴ Thomas Tütken ^2*

• ¹ Boise State University, Boise, United States
• ² Johannes Gutenberg University Mainz, Mainz, Rhineland-Palatinate, Germany
• ³ University of Kiel, Kiel, Schleswig-Holstein, Germany
• ⁴ Vetsuisse Faculty, University of Zurich, Zurich, Zurich, Switzerland

Hydrogen and oxygen isotope ratios in proteinaceous tissues have been used for some time in migratory, ecological, and archaeological studies. While the result of isotopic variation in drinking water and diet has been investigated with controlled feeding experiments and studies in the wild, there are few controlled feeding studies that manipulate the diet components and diet type, and this across different taxa. In this experiment, the diet fed to rats, guinea pigs, and quail varied from plant-based to insect-based and meat-based pelleted diets. We report the diet to tissue offsets for d 2 H (denoted Dd 2 H) and d 18 O (Dd 18 O) of tissue-bound organic matter in two tissue types: muscle and dentine collagen. The diet to tissue offset varies by diet type in muscle of all three species, by up to 16 ‰ (Dd 2 H) and 2 ‰ (Dd 18 O). In dentine collagen, a range of ~20 ‰ in Dd 2 H and ~1.5 ‰ in Dd 18 O are observed across diets, though in a smaller number of samples. Additionally, we note large variation in Dd 2 H and Dd 18 O by tissue type (d 2 H = ~60 ‰, d 18 O = ~3-4 ‰) and more moderate differences by species (up to d 2 H = 7.4 ‰, d 18 O = 1.5 ‰). The difference in consumer tissue Dd 2 H and Dd 18 O by diet type is important to consider as a source of isotopic variability for some studies such as migratory research or diet or drinking water reconstructions and (palaeo-)climate inferences drawn from them, particularly in species that may vary their dietary habits.