Table 1. GLMM of the influence of parental age on egg hatching success.
| Term | d.f. | Effect | s.e. | Wald stat (χ2) | P value |
|---|---|---|---|---|---|
| Day | 1 | 0.01144 | 0.005035 | 5.16 | 0.023 |
| Day2 | 1 | −0.00009522 | 0.000036212 | 6.91 | 0.009 |
| Day3 | 1 | 0.0000001941 | 8.1796E−08 | 5.63 | 0.018 |
| Clutch number | 1 | 0.2659 | 0.04786 | 30.88 | <0.001 |
| Clutch number2 | 1 | −0.09423 | 0.027588 | 11.67 | <0.001 |
| Within clutch order | 1 | 0.1597 | 0.06327 | 6.37 | 0.012 |
| Within clutch order2 | 1 | −0.2615 | 0.06610 | 15.65 | <0.001 |
| Maternal age | 1 | 4.083 | 0.6218 | 43.13 | <0.001 |
| Maternal age2 | 1 | −0.2845 | 0.04296 | 43.87 | <0.001 |
| Paternal age | 1 | 1.587 | 0.5048 | 9.88 | 0.002 |
| Paternal age2 | 1 | −0.1089 | 0.03483 | 9.78 | 0.002 |
d.f., degree of freedom; GLMM, Generalized Linear Mixed Model; s.e., standard error.
The aim of the analysis was to examine the potential influence of parental aging on the hatching success of their eggs. A binary variable was used which indicated whether eggs that had been incubated subsequently hatched. A logistic GLMM was implemented using a logit link function; constant=−20.06. In total, the analysis includes assessments of 58,977 eggs laid by a total of 2,580 females and fertilized by a total of 1,161 different males. Parental identity and year of breeding were controlled as random effects. Variables derived from parental age and clutch sequences data were loge transformed to improve model fit.
Numbers in superscript indicate that the terms have been fitted as a second/third order polynomial.