Quantitative Fatty Acid Signature Analysis in R
Add error to the calibration coefficients
Adjust diet composition estimates for prey fat content
Calibration coefficient for an augmented signature proportion
Compute gamma parameter of chi-square distance measure
Diet estimation objective function
Pool diet estimates to combined prey types
Diversive magnetic clustering
Compute the distance between two fatty acid signatures
Creats a map of the distance between pairs of fatty acid signatures
Distance between fatty acid signatures and their mean
Distance between pairs of fatty acid signatures
Estimate predator diet composition
Find realistic bootstrap sample sizes
Goodness-of-fit for modeled predator signatures
Leave-one-prey-out analysis
Pool lopo results to original prey types
Generate a regular grid of diet compositions
Generate random diet compositions
Make a ghost prey signature
Simulate predator signatures
Make prey partition
Parameterized mean objective function
Identify predator signature proportions beyond range of prey
Prepare fatty acid information analysis
Prepare fatty acid signature data for analysis
Replace invalid fatty acid signature proportions
Scale fatty acid signature proportions
An implementation of Quantitative Fatty Acid Signature Analysis (QFASA) in R. QFASA is a method of estimating the diet composition of predators. The fundamental unit of information in QFASA is a fatty acid signature (signature), which is a vector of proportions describing the composition of fatty acids within lipids. Signature data from at least one predator and from samples of all potential prey types are required. Calibration coefficients, which adjust for the differential metabolism of individual fatty acids by predators, are also required. Given those data inputs, a predator signature is modeled as a mixture of prey signatures and its diet estimate is obtained as the mixture that minimizes a measure of distance between the observed and modeled signatures. A variety of estimation options and simulation capabilities are implemented. Please refer to the vignette for additional details and references.