My laboratory at UC Riverside is now routinely analysing carbon, nitrogen, and hydrogen isotopes in amino acids. Our philosophy is that the power of the analysis and interpretation for understanding ecosystems and ecological relationships increases exponentially as another isotope is added. Carbon isotopes provide estimates of the source(s) of primary productivity to an organism; nitrogen isotopes in amino acids can determine trophic position; hydrogen isotopes can give clues to location and diet. Ph.D. student Jon Nye is using this approach for studying the ecology and diet shifts in pinnipeds (i.e. seals and sea lions) from Patagonia, South America. Bobby...

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