Table 1.
Results of the univariate mixed ‘animal model’ fitted to partition variation in aggressive behaviour with random intercepts for focal and opponent identity. Estimates of variance components and their correlations are given with associated standard errors. Random effects are expressed as the proportion of total phenotypic variation not attributable to fixed effects explained by each effect. Focal and opponent variances, as well as their covariance, are partitioned into environmental (PE) and genetic (G) components. For each model, variance terms are provided with a likelihood ratio test (LRT) between the given model and the previous model, with associated degrees of freedom (df) and values of P. The most parsimonious model (model 7) is denoted in bold face.
| Model | Variance σ² (SE) | Correlations r Foc-Opp (SE) | Test | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Focal | Opponent | Residual | PE | G | LogL | Χ² | df | P | ||||||
| PE (f) | DGE | PE (o) | IGE | |||||||||||
| 1 | — | — | — | — | — | — | 0.98 (0.03) | — | — | — | −1168.01 | — | — | — |
| 2 | 0.17 (0.02) | — | — | — | — | — | 0.83 (0.02) | — | — | — | −1131.75 | 72.52 | 0/1 | <0.01 |
| 3 | 0.17 (0.02) | — | — | 0.11 (0.02) | — | — | 0.71 (0.03) | — | — | — | −1116.89 | 29.27 | 0/1 | <0.01 |
| 4 | 0.17 (0.02) | — | — | 0.11 (0.02) | — | — | 0.71 (0.03) | −0.21 (0.11) | — | — | −1115.34 | 3.1 | 1 | 0.08 |
| 5 | — | 0.12 (0.03) | 0.05 (0.02) | 0.11 (0.02) | — | — | 0.71 (0.03) | −0.19 (0.14) | — | — | −1110.99 | 8.7 | 0/1 | <0.05 |
| 6 | — | 0.12 (0.03) | 0.05 (0.02) | — | 0.08 (0.03) | 0.03 (0.02) | 0.71 (0.03) | −0.20 (0.15) | — | — | −1109.15 | 3.68 | 0/1 | <0.05 |
| 7 | — | 0.12 (0.03) | 0.05 (0.02) | — | 0.08 (0.03) | 0.03 (0.02) | 0.71 (0.03) | — | 0.01 (0.18) | −0.83 (0.37) | −1107.05 | 4.2 | 1* | <0.05 |
*tested in addition over an equal mix of df = 1 and df = 2 (representing a test of variance and covariance together, against model 5), Χ² = 7.88, p < 0.05