Table 2. Results of a generalised linear model (GLM) testing potential factors influencing whether the frog Pelophylax nigromaculatus successfully digested the bombardier beetle Pheropsophus jessoensis in feeding experiments.
| Response variable | Explanatory variable (fixed effect) | Coefficient estimate | SE | t value | P value |
|---|---|---|---|---|---|
| Digestion successa | Intercept | 4.471889 | 4.45551 | 1.004 | 0.32 |
| Frog weight | −0.370908 | 0.30261 | −1.226 | 0.226 | |
| Beetle weight | −0.04681 | 0.023848 | −1.963 | 0.055c | |
| Frog weight × Beetle weight | 0.002329 | 0.00146 | 1.596 | 0.117 | |
| Beetle treatmentb | 2.011385 | 1.033049 | 1.947 | 0.057d |
Notes.
a
As the residual deviance was smaller than the residual degrees of freedom, a quasi-binomial error distribution (rather than a binomial error distribution) was employed. One and four live and dead beetles, respectively, were digested.
b
Live beetles were used as a reference.
c
The significance of this factor was checked using the likelihood ratio test (P = 0.028).
d
The significance of this factor was checked using the likelihood ratio test (P = 0.029).