Model coefficients and credible intervals for overall infection status.

How infection status (all trematodes combined) was affected by biomass of Potamopyrgus (Biomass Treatment: Control, with no Potamopyrgus, ambient levels of Potamopyrgus in Polecat Creek, and High biomass) for two taxa of native snails in Bayesian multilevel models [39, 40]. For the native snail Pyrgulopsis (A), the group level effects were the year that the experiment was conducted (year), the size of the experimental chamber (chamber size) and the experimental replicate (replicate) nested within Treatment. Because we only tested the dilution effect hypothesis with the native snail Galba (B) in one year and with all the same sized experimental chambers, the group level effect for Galba was replicate. Variables that significantly affected infection status possess 95% credible intervals that exclude zero and are bolded. For the group level effects, values in the Coefficients column are standard deviations for the Coefficient estimates.