Table 1.
General linear mixed models to analyse copepod behaviour in response to infection by parasites selected for or against host manipulation. Initial model for host manipulation: response approximately 1 + (1/population). Initial model for host activity: response approximately 1 + (1/population) + (1/copepod identity). Test statistics and p-values were obtained using likelihood ratio tests and are always for the comparison with the preceding (i.e. less complicated) model. n: host manipulation: 1231 copepods in 4 populations; host activity: 2462 observations on 1231 copepods in 4 populations. Significant p-values are highlighted in bold.
| factor | df | χ2 | p |
|---|---|---|---|
| host manipulation (df: 3) | |||
| + generation | 4.1 | 20.28 | <0.0001 |
| + infection | 5.1 | 27.44 | <0.0001 |
| + selection line | 7.2 | 41.96 | <0.0001 |
| + infection: generation | 8.1 | 14.88 | 0.0001 |
| + selection line: generation | 10.2 | 3.59 | 0.1658 |
| host activity (df: 4) | |||
| + parasite stage (predation suppression versus predation enhancement) | 5.1 | 428.66 | <0.0001 |
| + generation | 6.1 | 1.77 | 0.1436 |
| + generation: parasite stage | 7.1 | 20.39 | <0.0001 |
| + infection | 8.1 | 132.17 | <0.0001 |
| + selection line | 10.2 | 1.87 | 0.8362 |
| + infection: generation | 11.1 | 1.44 | 0.2460 |
| + selection line: generation | 13.2 | 0.91 | 0.5638 |
| + infection: parasite stage | 14.1 | 27.50 | <0.0001 |
| + selection line: parasite stage | 16.2 | 41.77 | <0.0001 |
| + generation: infection: parasite stage | 17.1 | 15.23 | 0.0001 |
| + generation: selection line: parasite stage | 19.2 | 3.62 | 0.1635 |