Simulating predator signatures in QFASA

What is it about?

Understanding animal diets is a critical aspect of ecology and quantitative fatty acid signature analysis (QFASA) has become an important method of estimating predator diets, especially for marine species. The accuracy (and other properties) of QFASA diet estimators is commonly evaluated using artificial predator “signatures” (percentage contributions of different fatty acids to adipose tissue) constructed from real prey signature data so that the true diet is known. However, current methods of constructing artificial predator signatures are subjective and likely produce signatures with unrealistic levels of variance that could influence diet estimates. Consequently, conclusions drawn from such simulation studies may misleadingly suggest QFASA will work either worse or better than it actually will. In this paper, I describe an objective method of constructing artificial predator signatures that produces signatures with the desired mean and realistic levels of variation. Use of this method in simulation studies should lead to more reliable assessments of how well QFASA estimators can be expected to estimate predator diets.

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Why is it important?

This research led to the first objective method of constructing predator fatty acid signatures with desired and realistic characteristics, contributing to a growing body of work providing new insights into the properties and capabilities of QFASA diet estimators that will be valuable in future studies of animal diets.