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.本研究借助贝叶斯多层模型（Bayesian multilevel models）[39, 40]，探究了臭鼬溪（Polecat Creek）中不同生物量水平的拟钉螺（Potamopyrgus）生物量（处理组设置为：无拟钉螺的对照组、原位拟钉螺生物量组、高生物量组）对两类本土蜗牛的总吸虫感染状况（所有吸虫合并统计）的影响。针对本土蜗牛Pyrgulopsis（A），其分组水平效应包含实验开展年份（year）、实验舱尺寸（chamber size）以及嵌套于处理组内的实验重复次数（replicate）。鉴于本研究仅在单一年份、使用相同规格实验舱的条件下，针对本土蜗牛Galba（B）验证了稀释效应假说，因此Galba的分组水平效应仅为实验重复次数（replicate）。对感染状况存在显著影响的变量，其95%可信区间不包含0，且已通过加粗格式标注。对于分组水平效应，系数列中的数值为系数估计值的标准差。