Table 1.
Statistical results from a generalized linear mixed-effects model examining the effects of atrazine exposure (presence or absence) at two times in Cuban tree frog tadpole development (early or late) on their survival (binomial response) in the presence or absence of the pathogen Batrachochytrium dendrobatidis (Bd). To test for short-term and long-term effects of atrazine on disease resistance, Bd exposure occurred immediately after the atrazine exposure or a mean of 46 days after the atrazine exposure, the latter of which was after metamorphosis. A subset of the tadpoles from a tank were exposed to Bd+ or Bd− inocula, and thus these individuals were nested within tank and treated as a random factor to ensure proper error structure.
| effect | d.f. | χ2 | p* |
|---|---|---|---|
| Bd (present or absent) | 1 | 12.50 | <0.001 |
| timing of Bd exposure (immediate or post-metamorphosis) | 1 | 5.91 | 0.015 |
| developmental window (early or late) | 1 | 0.10 | 0.758 |
| atrazine (present or absent) | 1 | 2.10 | 0.147 |
| Bd×timing of Bd | 1 | 1.39 | 0.238 |
| Bd×developmental window | 1 | 0 | 0.985 |
| Bd×atrazine | 1 | 4.90 | 0.027 |
| timing of Bd×developmental window | 1 | 3.38 | 0.066 |
| timing of Bd×atrazine | 1 | 1.05 | 0.305 |
| developmental window×atrazine | 1 | 0.75 | 0.386 |
| Bd×timing of Bd×developmental window | 1 | 1.49 | 0.222 |
| Bd×developmental window×atrazine | 1 | 0.22 | 0.637 |
| Bd×timing of Bd×atrazine | 1 | 0 | 0.983 |
| timing of Bd×developmental window×atrazine | 1 | 0.24 | 0.625 |
| four-way interaction | 1 | 0.08 | 0.772 |
*Log-likelihood ratio test based on type II sums of squares.