ANIMAL STUDIES: Diet Discrimination, Tissue Differences and Diet Changes Over Time

Figure 1. Bears that eat a diet of just nuts and berries have tissue d15N and d13C values lower than those of bears that also eat salmon (which is higher up the food chain). View larger image.	Figure 2. Collagen preserved in modern and fossil bones records an organism’s relative diet. Carnivores have higher d15N and d13C values than herbivores. View larger image.

Figure 3. Different tissues of gerbils have varying d13C values. Brain, muscle, and liver tissue best reflect the d13C signature of a gerbil’s diet. Note the large offset between diet and fat! Fat typically has lower d13C values than other tissues. View larger image.	Figure 4. When a gerbil’s diet is switched to food with a different d13C value, its tissues change over time to reflect this. This happens as carbon in the tissues is replaced. Some tissues show this change more rapidly than others. For example, liver tissue achieves the d13C value of the new diet in less than 80 days, whereas hair takes well over twice as long. View larger image.

References

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