Estimate trophic position using a one source model derived from Post 2002 using a Bayesian framework.
one_source_model(bp = FALSE)returns model structure for one source model to be used in a
brms() call.
logical value that controls whether informed priors are
supplied to the model for \(\delta^{15}\)N baseline.
Default is FALSE meaning the model will use uninformed priors, however,
the supplied data.frame needs values for \(\delta^{15}\)N
baseline (n1).
$$\delta^{15}N = \delta^{15} N_1 + \Delta N \times (tp - \lambda_1)$$
\(\delta^{15}\)N are values from the consumer,
\(\delta^{15} N_1\) is mean \(\delta^{15}\)N values of baseline 1,
\(\Delta\)N is the trophic discrimination factor for N (i.e., dn mean
of 3.4), \(tp\) is trophic position, and \(\lambda_1\) is the
trophic level of baselines which are often a primary consumer (e.g., 2).
The data supplied to brms() needs to have the following variables d15n,
n1, and l1 (\(\lambda\)) which is usually 2.
brms::brms()